Classics in the History of Psychology

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Definitions En - Es

Posted June 2000

Enactment [Lat. en + actus, from agere, to do]: Ger. (1) legislative Genehmigung einer Acte, Gesetzerlassung, (2) Verfügung, Verordnung; Fr. (1) action de passer une loi, (2) loi; Ital. (1) decretare una legge, (2) atto legislativo. (1) The act of enacting a law. (2) The law enacted; a legislative act.

The form of English legislation is the preparation of a bill for an act, its approval by the Lords and Commons, and its presentation by them to the Crown for the royal assent. The American form is generally the same, the final act being the approval by the executive. The general style of the commencement of the bill is Be it enacted, that is, may it be enacted. The executive assent first makes it an enactment. (S.E.B.)

Encephalon: see BRAIN.

Encyclopedia (philosophical): Ger. Encyclopädie; Fr. encyclopédie; Ital. enciclopedia. Applied to the entire round of philosophical studies, but varying with the particular writer's views of philosophy, from the Positivism of the French ENCYCLOPEDISTS (q.v.) to the Logicism of the NEO-HEGELIANS (q.v.). (J.M.B.)

Encyclopedists [Lat. encyclopaedia]: Ger. Encyclopädisten; Fr. Encyclopédistes; Ital. Enciclopedisti. The French thinkers who in the third quarter of the 18th century edited the Encyclopédie ou Dictionnaire raisonné des Sciences, des Arts et des Métiers (28 vols., 1751-72; Supplément, 5 vols., 1776-7; Table analytique, 2 vols., 1780), or contributed to the work.

Of the group, Diderot was editor-in-chief, d'Alembert his principal associate until the retirement of the latter in 1757. D'Alembert was the author of the Discours préliminaire, in which the plan of the work was defined on the basis of Bacon's division of the sciences and the Baconian method. Rousseau also ceased to write for the Encyclopédie in 1757, and thereafter manifested an active hostility to his former collaborators. Other notable contributors were Voltaire, Grimm, d'Holbach, Quesnai, Turgot, Marmontel, Duclos, de Jaucourt. Haller and Condorcet aided in the preparation of the supplementary volumes. Montesquieu at his death, in 1755, left an article partly finished. Buffon was early associated with the work, but it is not certain that anything from his pen was actually printed (Morley, Diderot, i. 129-30). Writers of lesser rank were numerous and from all classes in society. After the defection of d'Alembert, Diderot remained the sole principal editor, and by his unflagging energy and courage carried the enterprise through to its termination. Among the many difficulties which confronted him, not the least vexatious were the opposition of the orthodox party, and the interference of the authorities. For the Encyclopédie was more than a great 'dictionary of sciences, arts, and trades'; it was conceived in the spirit of the Illumination movement, and it carried the principles, as well as the results, of the new thinking into the culture of the time. Thus it became at once a storehouse of information and a revolutionary force.

Literature: DAMIRON, Mém. pour servir à l'Hist. de la Philos. au XVIIIe Siècle, i. 3, especially 240-3, ii. 5, especially 10-12; K. ROSENKRANZ, Diderots Leben u. Werke, i. 147-253; JOHN MORLEY, Diderot and the Encyclopaedists, i. chap. v. Also the histories of philosophy (as WINDELBAND, Gesch. d. neueren Philos., i. § 44), and the histories of literature (as HETTNER, Litteraturgeschichte d. 18ten Jahrhunderts, ii. Absch. 2, especially Kap. 1). (A.C.A.Jr.)

End (ethical): for equivalents, see the following topic. The ultimate purpose which ought to be aimed at in conduct, and to which other purposes ought to be subordinated.

Ethics may be said to be a theory of the end or ends of conduct. This view was first made definite and prominent by Aristotle, whose whole doctrine is dominated by the conception of end (teloV). Starting from the position that well-being (eudaimonia) is by common consent the end, he seeks a more precise definition of this conception. And modern ethical controversy is largely concerned with the claims of rival conceptions (e.g. happiness, perfection, self-realization) to be regarded as the ethical end. This teleological view of ethics is contrasted with the quasi-jural view in which moral law is the ultimate conception (as in Kant and the intuitional school). (W.R.S.)

From one point of view the definition of ethical end in terms of actual psychic purpose is a mistaken one. Ends are -- in so far as immediate to the individual, i.e. in so far as they are purpose -- particular aspects of conation, and in their most generalized form still particular with reference to one another -- general only with reference to the particular cases generalized or subsumed under each, and that in the peculiar sense of subordination in a system. If an end becomes really universal, just then it loses its ethical significance; since it is imposed upon the individual or upon the particular conative tendencies, not developed by their systematization, so that it is not the individual's psychic end. Further, the genetic point of view is quite ignored by this form of definition. As consciousness develops, the synthesis of conative processes becomes ever more complex and indefinitely varied, and the resulting psychic ends or ideals ever richer and more adequate to experience. The individual's concrete purpose -- even his most general purpose of life-ideal -- is therefore never universal. In so far as he treats it as universal, it is as a formal regulative demand, not a purpose; and just here arises the antinomy of good intention with reference to purpose, and bad performance with reference to law.

We come, therefore, to require a definition of ethical end from the point of view of the psychological rather than the psychic (see PSYCHIC AND PSYCHOLOGICAL) -- an objective rather than a subjective determination of the end; hence the definition given: what 'ought to be the purpose' is the end. But, although this is the definition justified by history -- despite much confusion between the two points of view -- the question again leads us into a theoretical cul de sac. If we mean, What end, if fulfilled by all men, would be of most worth? that cannot be answered except on purely logical grounds; for to determine it as value or worth would be to attain the complete systematization of ends, which we have seen above is not only not actual, but genetically impossible. But to determine it on logical grounds is to determine a logical end, not one of worth; a situation in which the demands of logic primarily, not those of action or appreciation, would be completely satisfied. If, again, we mean, What end fulfilled would also fulfil the final world-end, would realize cosmic teleology? -- that statement, just because it is in terms of the cosmic, not of the personal, can be answered only in terms of the cosmic, i.e. by science. What -- the question becomes -- what, as fact, is the end of cosmic, including human, evolution? This can find a formal answer, again, from the forms of knowledge, a logical answer; but such an answer cannot be made a regulative principle to determine the individual's ought; for the individual is under the lead of certain facts, not of all knowledge, and to say that he ought to act from the point of view of all knowledge -- that is, from the point of view of the universal element in knowledge -- is to mock him with logical tautologies, when he needs practical adjustments. That is to say, if all men gave up their practical adjustments to pursue what we tell them they ought to pursue in view of a universal teleology, the teleology would be the first thing to suffer.

The question of psychic end, therefore, is -- in the more modest form in which it is capable of solution, and even of intelligible statement -- the scientific question of (1) the systematization of individual concrete purposes in enlarging systems: the determination of voluntary conations; (2) the origin and development of the ethical consciousness in the social conditions under which the individual's voluntary life is lived. These are both psychic or mental determinations. If they be handed over to psychology, we have then left over for ethics the objective questions: (1) the ethnological and social forms which ethical strivings have taken on; and (2) the place of these in a general philosophy of reality, which shall include that of a general teleology.

The strictly ethical questions, then -- making use of the psychology of the conative life in advance -- are: (1) What ends have men pursued as good and bad? (2) What ends may they pursue as good and bad? (3) What significance does the category of good and bad, as thus filled in with instances, have in the make up of things? Cf. the remarks on the ethical end under ETHICS.

The last question is a metaphysical one, concerning the broad distinction between science of fact and appreciation of worth; and its problem is that of finding a category in which facts and worths are both subsumed in a profounder synthesis. Cf. ORIGIN versus NATURE, and METAPHYSICS. (J.M.B.)

Literature: SIDGWICK, Meth. of Eth., I. vi; general works on ethics and psychology; and BIBLIOG. F, 2, i. (W.R.S.)

End (in psychology) [AS. ende]: Ger. (1) Zweck, Ziel (most general, remote), Beweggrund (in cases of voluntary movement), (2) Ende; Fr. (1) but, (2) fin; Ital. (1) scopo, (2) fine. That which satisfies a conation. Cf. PROJECT (voluntary), PURPOSE, PLAN, INTENTION, and DESIGN.

But there are two points of view from which this satisfaction may be regarded. We may consider (1) the form in which the end appears to the striving subject before its attainment, or (2) the psychical state which arises when it is completely attained.

(1) Thus from the first point of view the end consists in some positive result as ideally represented or in some manner cognized before its achievement.

(2) From the second point of view, the end consists in that relative cessation of conative activity which depends on the fact that the activity has completed itself and has nothing further to accomplish. It will consist not in pleasure or relief but in satiety. If a conative process is allowed to develop freely without interruption or repression, it tends to go on until a certain result ensues, and when the result is attained it ceases of itself; this result is the termination, and in that sense the end of the process. It is desirable that these two meanings should be marked by some difference of terminology. We therefore propose to use 'end' for (1), and 'terminal end,' or simply TERMINUS (q.v.), for (2). (G.F.S.- J.M.B.)

The desirableness of this appears from the confusion of the two meanings which one finds in ethical discussions, especially when the conception of terminus is generalized into what we are calling the END-STATE (q.v.) of mental process generally; the so-called ethical end being treated alternatively in one way and then in the other. The distinction between end and end-state has been suggested by various writers in different expressions, as e.g. distinctions between 'subjective and objective' end, 'conscious and unconscious' end, 'psychic' as opposed to psychological, 'biological,' and 'philosophical' end, the 'end' as distinguished from the 'object' of desire, &c. Writers on hedonism and utilitarianism revel in this confusion; and it takes on another of its many-headed forms in the idealists who make some universal or abstract conception still an 'end,' confusing or identifying the end-state of a cosmic or thought process, viewed objectively, with the individual's mental end. See END (ethical).

A further distinction should also be made between two forms of end in the first and proper sense -- that between 'concrete' and 'ideal,' or between 'immediate' and 'remote' ends. The concrete or immediate end is usually incidental to a larger intention in which the ideal, or this ideal end, takes form -- the so-called 'remote' or 'ultimate' end. See CHOICE (for a similar distinction). This larger determination includes a system of concrete ends, and may itself have an explicit conscious end or only an end-state as its goal. The grocer's remote end is to get rich; his end-state is vital satisfaction; his concrete ends are weighing sugar, buying tea, and collecting bills. Cf. TELEOLOGY. (J.M.B., G.F.S.)

Literature: (in which the distinction of (1) and (2) is made): LIPPS, Grundthatsachen des Seelenlebens, 623 ff.; BALDWIN, Feeling and Will, chap. xvi; STOUT, Man. of Psychol., Index. See also the textbooks of psychology and ethics. (G.F.S.- J.M.B.)

End of the World: see ESCHATOLOGY.

Endoderm [Gr. endon, inner, + derma, layer]: Ger. inneres Keimblatt; Fr. endoderme; Ital. endoderma or entoderma. The inner layer of coelenterate animals, or the inner of the two primitive cell-layers of the embryo mammal, often termed hypoblast. See BLASTODERM, EMBRYO, and HYPOBLAST. (C.LL.M.- E.S.G.)



End-organ: Ger. Endorgan; Fr. organe nerveux périphérique (Y.D.); Ital. terminazione nervosa. (1) Any organ which forms a terminus of a path of nervous conduction. Its function may be to initiate or to receive the discharge.

(2) Usual meaning: the peripheral terminus. Most end-organs are so related that they clearly perform both of these functions. Even in the case of motor and other efferent nerves the peripheral end-organ seems to exert some sort of reactionary influence. It seems probable that every fibre is normally in a state of neural tension between its end-organs, and that the discharge is the rhythmical readjustment of the equilibrium which has been disturbed by the stimulus at one terminus. Cf. Brain Origin, by Sir William Broadbent, Brain, xviii (1895). See HEARING, VISION, MUSCLE, SENSE ORGAN, &c. (H.H.)

Endorsement: see BELIEF, and SYNKATHESIS.

Endothelium [Gr. endon, within, + qhlh, a papilla]: Ger. Endothel; Fr. endothélium; Ital. endotelio. A term widely used (His) to designate the cellular lining of cavities, blood-vascular, lymphatic or synovial, which do not open, directly or indirectly, to the exterior. It consists of a single layer of thin cells joined at their edges. Cf. EPITHELIUM. (C.F.H.)

End-plate: Ger. Enplatte, Nervenhügel Fr. plaque motrice; Ital. lama terminale. The terminal organ of a motor nerve embedded in the muscular fibre. See NERVOUS SYSTEM (nerve). (H.H.)

End-state: Ger. Endzustand; Fr. état final; Ital. stato finale. (The foreign equivalents are suggested.) The goal or result of a concrete mental DETERMINATION (q.v.); that state in which any specific process in consciousness issues and completes itself. See END.

For example, belief is the end-state of argumentation, choice the end-state of deliberation, accomplished action that of effort, &c. In cases of conative process such the word TERMINUS (q.v.) is suggested, seeing that here the end-state is one of satiety or real termination. (J.M.B., G.F.S.)

Endyma [Gr. enduma, garment]: Ger. Ependymium, Ependym; Fr. épendyme; Ital. ependima. The epithelial lining of the entire medullary tube and the cavities formed from it. Synonym: Ependyma. See NERVOUS SYSTEM (embryology), and NEUROGLIA. (H.H.)

Energeia [Gr.]: see GREEK TERMINOLOGY (6), and POWER.

Energism [Gr. en + ergein, to work]: Ger. Energismus; Fr. énergisme; Ital. energismo. The view that the highest good consists in ethical activity, or the realization of objective rather than subjective life-conditions (Lebensinhalt). Used by Paulsen, Einleitung in d. Philos., 432 (Eng. trans.). (J.M.B.)

Energy [Gr. energeia]: Ger. Energie; Fr. énergie; Ital. energia. An ideal physical quantity manifesting itself under different forms which are so related that one form can never be increased except at the expense of an equal quantity in some other form.

The conception was first developed in mechanics in the two forms of kinetic and potential defined below, and the term force (Kraft) was applied to it. It was for a time supposed that all other forms could be reduced to one of these two, but this view now seems untenable.

The forms of energy hitherto recognized may be defined and measured as follows: --

(1) Kinetic energy, or energy of motion, is measured by, or equal to, the product of one-half the mass of a body into the square of its velocity, or, in algebraic language, 1/2 mv2 = E. In the case of a system of bodies such a product may be formed for each body, and the sum of all the products is the kinetic energy of the system. If at any moment we could determine the velocity v of each particle of matter in the solar system, the sum of all the products 1/2 mv2 would be the total kinetic energy of the solar system at that moment.

(2) Potential energy, or energy of position, is in mechanics an integral of which the differential is the product of a force acting between two bodies into the differential of the distance by which they are separated. In the common case of a heavy body it increases with the height of the body above the surface of the earth. In the case of a system of bodies attracting each other with a force inversely as the square of the distance, the potential energy is the sum of the quotients formed by dividing each product of the masses of every two of the bodies by their distance apart, and regarding the sum as algebraically negative. Thus if the masses are m1, m2, m3, &c., and the distance of the mass m1 from m2 is r1, 2, and so with all the other pairs, the potential energy at any moment is

The relation of kinetic and potential energy may be illustrated thus: -- If P be a point at a height a above a level plane AB, and a body be dropped from P or thrown from it in any direction whatever with any velocity whatever, or suffered to slide without friction from P along an inclined plane PB or PC, the square of its velocity with increase by the same amount 2 ag (g being the acceleration of gravity) during the fall from P to AB, no matter by what path the fall takes place, or what part of the plane AB is reached. That is, if it leave P with the velocity vo, and we call v the velocity with which it reaches AB, we shall always have

v2 = vo2 + 2 ag,
 and therefore, for the kinetic energy,

1/2 mv2 = 1/2 mvo2 + mag.

However a body is thrown, if we leave out resistance, its velocity and its varying height h above any arbitrary plane or level, say the earth's surface, during flight are such that the quantity

                                                                           1/2 mv2 + mgh, or E + P,                                                            (A)

is constant until it reaches the earth or is in some way interfered with, so that, if the kinetic energy 1/2 mv2 increases, the potential energy mgh or P will diminish, and vice versa.

(3) The energy of heat. The theorem that E + P remained constant during the motion of any system of bodies acted on only by their mutual attractions was proved by the mathematicians of the 18th century. But they had to couple this theorem with the important proviso that the bodies must never come into collision, because then some of the quantity E + P would be lost through a diminution of the velocity of the colliding bodies, and hence of E. Then it was shown by Rumford and others that this loss of E was always accompanied by the generation of an amount of heat proportional to the loss of E. If we call H the amount of this heat, expressed in appropriate units, we should then have

E + P + H = constant,

even when the bodies come into collision, or, in the case of a projectile, after it strikes the ground. Thus, by adding H to the equation (A), we have

1/2 mv2 + mgh = E + P + H,

which remains true after the fall of the body, because the annihilation of velocity, and hence of E, is compensated by the generation of an equivalent amount H of heat, which raises the temperature both of the projectile and of the ground where it struck.

As an illustration, when a solid shot is fired from a modern rifled gun at an armour plate a flash of fire is seen, and plate and shot may both be partly melted by the heat.

(4) Energy of molecular condition. It is found that when bodies change their state, as when water freezes or evaporates, or when two substances combine to form a compound, heat may be generated or disappear, according to the character of the change. A general law is that if such bodies are restored to their original state, the loss of heat in the one process exactly balances its gain in the other; and this, however great the number of intermediate states the bodies may pass through. We may call the sum total of this energy C.

(5) Radiant energy or radiance. Every hot body radiates its heat through the space around it, thus imparting energy to the ether. The energy thus imparted is now believed to take a form of waves of electric energy, known as Maxwellian or Herzian waves, and its amount is exactly equal to that which the hot body loses. So, if we call R the total heat-energy of the ether, R will constantly gain as the body loses its heat-energy H, and vice versa.

(6) Electrical energy. The generation of electricity requires an expenditure of energy equal to half the product of the quantity of electricity generated into its potential. Thus, as electric energy L appears, energy in some other form disappears, and vice versa.

(7) Magnetic energy, which appears when a body is magnetized. We may call it M.

All known forms of energy may be included under one of these seven heads, so that the sum total of energy of all seven forms in the universe E + P + H + C + R + L + M remains for ever constant. This is the theorem of the 'Conservation of Energy.' But the values of the seven separate quantities are continually changing, and these changes may be conceived as transformations of some of the kinds into others. The usual rule of nature is that position energy P is being constantly converted into kinetic energy E, and this into heat H, which again is converted into radiance R, which is propagated indefinitely through the ether. The store of P in the beginning consisted in the diffusion in space, as nebulous matter, of the materials now forming the stars and planets; and this store is being converted into E by the process of condensation produced by the mutual attraction of all the matter of the universe.

It is sometimes supposed that thought or mental action of some sort may be a distinct form of energy. This cannot be. Mental action may be, and doubtless always is, accompanied by an exhibition or transformation of energy, but the energy itself can be only that of the matter composing the brain and nervous system.

Literature: a very complete popular exposition of the theory of energy and its conservation is found in HELMHOLTZ, Ueber die Erhaltung der Kraft: Populäre wissenschaftliche Vorträge, Heft 2 (1876). Instructive and yet simpler are THOMSON'S two addresses, On the Origin and Transformation of Motive Power, and On the Sources of Energy in Nature available to Man for the Production of Mechanical Effect (Popular Lectures and Addresses, ii). SPENCER'S exposition in his First Principles is defective, through trying to extend the conception of energy into fields where no transformation of mechanical energy into the concepts of the field is possible. (S.N.)

The term energy is used also by the advocates of 'dynamic monism' to indicate the principle of real unity which underlies all phenomena. Cf. E. Morselli, Filosofia monistica in Italia, in Riv. di Filos. Scient. (1886); Fontana, Monismo e Dinamismo (2nd ed., 1897); Haeckel, Der Monismus and Die Welträthsel (1899). (E.M.)

Enfranchisement: see FRANCHISE.

Engel's Law: Ger. Engel' sches Gesetz; Fr. loi d'Engel; Ital. legge di Engel. A generalization with regard to the relative proportions of income spent for different purposes by workmen of different grades. The lower the income, the greater is the proportion spent for food.

First given definite shape by the Saxon statistician Engel in 1857. Subsequent observations in different countries have shown a surprising degree of constancy in the results of all careful statistics of family budgets. (A.T.H.)

En kai pan [Gr.]. Literally, 'one and all': used to characterize the theory of PANTHEISM (q.v.). (J.M.B.)

Enlightenment [AS. licht, light]: Ger. Aufklärung; Fr. libre-pensée, émancipation intellectuelle; Ital. secolo (or periodo) dei lumi. A philosophical period of the 18th century characterized by an impetus to culture. The group comprises a large number of men of varying tendencies.

A striving toward freer, more independent thinking, emancipation from established dogmas, and an empirical or materialistic leaning characterized the period. Lessing, Mendelssohn, Reimarus, Tetens, Herder, Locke, Newton, Voltaire, Condillac, and Diderot are representatives of the movement, which affected Germany, England, and France. Cf. this topic in the histories of philosophy. (H.R.S.)

Ennui [Fr.]: Ger. Langeweile; Ital. noia. The unpleasant feeling which arises through persistence in more or less futile mental activity, or through the persistent presence of tendencies to mental activity which fail to find satisfying objects for their exercise. (G.F.S.)

Entelechy [Gr.] see POWER.

Enterozoa [Gr. enteron, gut, + zwon, animal]: Ger. Eingeweidewürmer; Fr. entérozoaires (suggested, not in use -- Y.D.); Ital; enterozoi. That group or grade of animals characterized by the presence of a digestive cavity or enteron.

A term proposed by Lankester. Haeckel's term METAZOA (q.v.) is more frequently employed. Lankester divides the animal kingdom into two grades: (1) the Plastidozoa ( = Protozoa), which consist either of single cells or colonies of equivalent cells, and (2) the Enterozoa ( = Metazoa), in which two differentiated layers surround a primitive digestive cavity. The enteron in some rare cases originated directly from the BLASTOCOEL (q.v.), an orifice arising disruptively, and the hypoblast and epiblast originating by DELAMINATION (q.v.). More commonly it arises by INVAGINATION (q.v.). See GASTRAEA THEORY, and EMBRYO.

Literature: E. R. LANKESTER, Adv. of Sci. (1890), in which the art. Zoology, from the 9th ed. of Encyc. Brit., is reprinted with some modifications; F. BALFOUR, Compar. Embryol. (C.LL.M.)

Enthusiasts [Gr. en + qeoV, a god]: Ger. Enthusiasten; Fr. enthousiastes; Ital. entusiasti. The name given to a sect of Christian monachists, or monks, who began to flourish in Syria towards the close of the 4th century. They believed that, as a result of the Fall, every man was inhabited by an evil spirit, who ruled him. Asceticism, and especially inward prayer (hence their other common name, Euchites), could, notwithstanding this, so affect a man as to enable him to enter at length into direct communion with the Holy Spirit -- hence the name Enthusiasts. They were called also Messalians, Adelphians, Lampetians, Marcionists. Their doctrines are of some importance for ethics as illustrating the logical consequences of extreme asceticism, mysticism, and pure contemplation. Neander calls the Enthusiasts the first mendicant friars.

Literature: NEANDER, Church Hist. (Eng. trans.), iii. 341 f.; SALMON, in Smith and Wace's Dict. of Christ. Biog., 'Euchites.' (R.M.W.)

Enthymeme [Gr. en + qumoV, mind]: Ger. Enthymem; Fr. enthymème; Ital. entimema. A reasoning in which some part of the grounds for the conclusion (i.e. one or other of the premises) is suppressed in the statement.

According to Aristotle, the enthymeme is a syllogism from probabilities or signs, and he assigns to it in rhetoric a definite function as corresponding there, in the special field of rhetoric (i.e. persuasion), to syllogism in purely intellectual or scientific matter. It would not therefore have been, in Aristotle's view, essential to the enthymeme that its statement should be elliptical; but his expressions or illustrations lend themselves readily to that interpretation, which, after the distinction between apodictic and dialectical reasoning had been rejected from logic, was naturally adopted.

Literature: the fullest historical discussion of points relating to the Enthymeme is given by HAMILTON, Discussions, 154-7; Lects. on Logic, lect. xx. See also GROTE, Aristotle (2nd ed.), 202-3; COPE, Introd. to Arist. Rhetoric, 103 ff., and MANSEL'S ed. of Aldrich (4th ed.), App. F., where (218) the correct explanation of the etymology of the term is given. (R.A.)

Entity and Ens [Lat.]: see LATIN TERMINOLOGY (5), BEING (3), and REALITY AND EXISTENCE.

Entoptic Phenomena [Gr. entoV + optikoV, pertaining to sight]: Ger. entoptische Erscheinungen (or Phänomene); Fr. phénomènes entoptiques; Ital. fenomeni endottici. Visual appearances due to processes within the eye itself are called entoptic, and the processes entoptic phenomena. (E.B.T.- J.M.B.)

The principal entoptic phenomena, if we take the phrase in its widest meaning, are the following: (1) Under certain experimental conditions we may perceive the shadow of the iris, the presence of liquids on the surface of the cornea, corneal specks, lines and blotches from the front part of the lens and its membrane, as well as the figures termed MUSCAE VOLITANTES (q.v.), &c. Le Cat's experiment, well calculated to show these phenomena, is as follows: -- Set up a short-focus lens at a distance from a source of light, and place in the focus of the lens a card with a hole made by a fine pin. The rays entering the eye are not focussed on the retina, but so refracted as to traverse the eye in a nearly parallel direction. Sharp shadows of objects in or on the eyeball are thus thrown on the retina. The objects seen on the outside of the corneal surface, since they are not really within the eye, are termed by Laqueur 'pseudentoptic' phenomena.

(2) Move a candle to and fro, below and slightly to the side of the eyeball, and as close to the eye as is convenient. Shadows of the retinal blood-vessels, and indications of the borders of the fovea centralis, and discernible.

(3) Look through a pinhole, held close to the eye, at an illuminated surface. Move the pierced card quickly, in circular sweeps. Shadows of the retinal vessels in the neighbourhood of the fovea will be seen. The macular region shows granulations (possibly retinal cones).

(4) Look fixedly at a misty sky, or through a blue glass at a clear sky or uniformly white surface (cloud, &c.). Bright yellowish points, followed by shadowy darker specks, will be seen taking a rapid course in fairly constant directions. The phenomena are those of retinal circulation.

(5) Move the spread fingers quickly to and fro before eyes, or look steadily at a FLICKER (q.v.) of a moon's disk of black and white sectors. The macula lutea becomes visible; streams of fine particles, possibly the lymph corpuscles, are seen; and, sometimes, elaborate patterns, the shadow-figures of Purkinje.

(6) Bergmann's experiment: look at the vertical lines of a fine grating; the lines are wavy and beaded in appearance. The phenomenon is supposed to be due to the mosaic arrangement of the cones.

(7) Appearance of the BLIND SPOT (q.v).

(8) Pressure applied to the eyeball produces phosphenes (circular patterns of light and dark alternating colour-patches) and 'movement figures' (pulsing colour-figures). A jerk of the eyes gives a blue spot surrounded by a yellow band, due to mechanical retinal stimulation at the edge of the blind spot.

(9) Adaptation to dark: IDIORETINAL LIGHT (q.v.), in the form of light chaos, light dust, together with subjective black or grey. On Müller's theory the grey is of central origin. See Visual Sensation under VISION.

Literature: HELMHOLTZ, Physiol. Optik (2nd ed.), 184; SANFORD, Course in Exper. Psychol., expts. 110-21, 170. (E.B.T.)

Entozoa [Gr. entoV, within, + zwon, animal]: Ger. Parasiten; Fr. entozoaires (not in use); Ital. entozoi. A term formerly used for internal parasites.

Since these do not form a natural group, the term is now discarded, though the word is still occasionally met with. It was introduced by Rudolphi. (C.LL.M.)

Entrepreneur [Fr.]: Ger. Unternehmer; Fr., see topic; Ital. intraprenditore, impresario. An employer who is also a speculator.

Introduced into current English usage by F. A. Walker. Down to a comparatively recent time it was the custom to speak of the man who takes the direction and risk of industrial enterprise as the 'capitalist'; of his return as 'profit'; and to analyse this profit into interest and wages of superintendence. Walker showed, as Mangoldt had done before him, that these two elements in profit are subject to distinct laws, and may be received by distinct persons. The capitalist receives interest; the man who furnishes the management receives true or net profit. This man Walker was at first inclined to call the undertaker, but he afterwards fell back on the French term entrepreneur. The entrepreneur's profit is due partly to his superior skill in organizing labour, but chiefly to foresight in predicting the wants of the market. George says: 'It is not as an employer of labour, but as a speculator in the products of labour, that the producer needs capital' -- an over statement, but with a basis of truth. (A.T.H.)

Environment [Fr. environner, to surround]: Ger. Umgebung, Umwelt, Lebensverhältnisse; Fr. milieu, conditions ambiantes, ambiance; Ital. ambiente, mezzo, condizioni mesologiche (E.M.). A term for the totality of external circumstances and conditions which affect the organism at any stage of its existence; also used of the organism as a whole in relation to its constituent parts or cells. (C.LL.M.- E.B.P.)

Rendered current as a technical term in biology by Herbert Spencer, who conceived the organism and its environment as constantly acting and reacting upon each other. It is applied in a figurative sense to the conditions of the mental life in the phrase 'moral,' 'social environment,' &c., for which the French term milieu is also much used by writers in English. The phrase 'bionomic conditions' (bionomische Verhältnisse) has recently come into use, together with the term BIONOMICS (q.v.). (C.LL.M.- J.M.B.)


Epagoge [Gr. epi + agein, to bring]: Ger. Epagoge; Fr. syllogisme épagogique; Ital. induzione. Argument by INDUCTION (q.v.). (J.M.B.)

Epiblast [Gr. epi + blastoV]: Ger äusseres Keimblatt, Hornblatt; Fr. épiblaste; Ital. epiblasto. The outer of the two primitive layers of the embryo animal, also termed ECTODERM (q.v.).

The term is due to Michael Foster. First published (1871) by Huxley (Anatomy of Vertebrated Animals), who considered the epiblast to be homologous with the ectoderm, or outer layer, of the coelenterates. The origin of the two primitive layers (epiblast and hypoblast) appears in some cases to be by INVAGINATION (q.v.), and in others by DELAMINATION (q.v.). Some biologists consider the one, some the other, as the more primitive method of origin. See GASTRAEA THEORY, ECTODERM, and EMBRYO. (C.LL.M.- E.S.G.)

Epicheirema [Gr. epiceirhma, an attempted proof -- Aristotle]: Ger. Epicherem; Fr. épichérème; Ital. epicherema. A syllogism in which one or both of the premises is supported by a reason. (J.M.B.)

Epictetus. Stoic philosopher, born at Hierapolis, Phrygia, about 60 A.D. The slave of Epaphroditus in Rome; he was made free, and then banished, with other philosophers, in 89 A.D. by Domitian. He then began teaching and lecturing at Nicopolis in Epirus. He wrote little, remarks taken down by his pupil Arrian in two treatises, the 'Discourses' and the "Manual,' being the source of our knowledge of him.

Epicureanism: Ger. Epicurismus; Fr. Épicurisme; Ital. Epicureismo. The theory of Epicurus: in particular, his ethical doctrine that pleasure is the chief good (the only thing worth having on its own account), and that each man's pleasure is his own chief good -- in the pursuit and attainment of which his moral excellence consists.

The doctrine of Epicurus and his disciples was hardly so much a philosophy, in the sense in which Platonic, Aristotelian, and even Stoic doctrines were philosophies, as a plan for the conduct of life. Logic and natural science are in it subordinated to the moral doctrine. Ideas or conceptions must be derived from felt sensations; language must consist of terms each referring to a distinct and clear conception -- this is the basis of his logic. His natural science is even less original, although it is more elaborate: all reality is material; and the play of the atoms accounts for the universe and all its contents. His only variation from Democritus is the assumption of a spontaneous swerving on the part of the atoms varying their downward motion, to account for the formation of aggregates, and so of life and mind. The whole theory of reality, like the theory of knowledge, is, however, a mere preliminary to clear the way to the peaceful and happy life, which Epicurus puts forward as resulting from the abolition of the fear of the supernatural. The gods exist in intermundane spaces, but have no concern with or influence upon human affairs. And with the fear of the gods disappears the fear of death. 'Good and evil are only where they are felt, and death is the absence of all feeling.' The affairs of the state are equally disturbers of the happy life, and from them Epicurus counsels withdrawal; their place being taken by the more flexible bonds of friendship. Health of body and tranquility of mind are the sum and substance of this happy life. Pleasure is the first good; but, if all pains were removed, pleasure could be varied only, not increased in amount.

Pleasure is always desirable in itself from its correspondence with our nature; but it is not always to be chosen, for it may lead to pains greater than itself. Some desires are not even natural; and some natural desires are not necessary; and of the necessary desires, the satisfaction of some is necessary for happiness, of others for an unperturbed frame of body, of others for life itself. 'If thou wilt make a man happy,' he is reported to have said, 'add not unto his riches, but take away from his desires.' Desire should be regulated by prudence, from which all the other virtues follow. 'We cannot live a life of pleasure which is not also a life of prudence, honour, and justice; nor lead a life of prudence, honour, and justice which is not also a life of pleasure.'

This theory of life Epicurus himself illustrated in the midst of a circle of friends -- men and women -- who frequented his garden at Athens. Abjuring the conventional bonds of society, he became the centre of a quasi-religious community, and the founder of a school which received and perpetuated his teachings with devotion, and without venturing on any important variation of opinion. The doctrine soon spread not only in Greece and Italy, but also in the barbarian world; the school also encountered persecution, mainly on account of its anti-political and anti-religious views.

The greatest literary representative of Epicureanism is Lucretius (De Natura Rerum, 54 B.C.). Atticus and others of the friends of Cicero belonged to the sect; and the writings of Philodemus, an Epicurean of the same period, have been disentombed from the ruins of Herculaneum. Epicureanism was one of the four philosophical schools endowed by the Emperor Marcus Aurelius about 176 A.D.; but, in the end of the 4th century, the Emperor Julian records the disappearance of the creed. The Renaissance led to the revival of the tendency towards a natural life and its enjoyment, which characterized Epicureanism. As a system it was resuscitated by Gassendi (1592-1655), who was not without followers at the time. The fundamental doctrine of Epicurus -- that pleasure is the end of life -- has perhaps never been without adherents. But the modern greatest happiness theory, as presented, for example, by Bentham, has many points of divergence from, as well as of similarity to, Epicurianism. In particular, it does not reaffirm the doctrine that the control of desire, rather than its satisfaction, is the means to a happy life; and it is largely a political theory.

Our knowledge of Epicurean doctrine depends chiefly on the fragments of Epicurus and his followers preserved by Diogenes Laertius and Stobaeus; on the discoveries at Herculaneum; on the writings of Cicero, and on the poem of Lucretius.

Literature: Histories of Philosophy; GUYAU, La Morale d'Épicure (1878); W. WALLACE, Epicureanism (1880). (W.R.S.)

Epicurus. (337 or 341-270 B.C.) Born on Samos, he professed to be self-taught, but was probably a pupil of Xenocrates in youth. In 319 or 323 B.C. he visited Athens, travelled in Ionia, and opened a school in Mytilene. In 306 he returned to Athens, bought a garden, and founded the Epicurean School of Philosophy. He wrote much, but only a few letters, preserved by Diogenes Laertius, have come down to us. See EPICUREANISM.

Epidemic (mental): Ger. geistige Epidemie; Fr. épidémie mentale; Ital. epidemia psichica. See CONTAGION (mental).

Epigenesis [Gr. epi + genesiV, production]: Ger. Epigenese; Fr. épigenèse; Ital. epigenesi. The hypothesis that in the differentiation of structure during embryological development all characters are produced, not having been present before; as opposed to the hypothesis of PREFORMATION (q.v.), i.e. that such differentiation is an unfolding of characters already preformed in the germ.

Harvey (1651) somewhat prophetically gave expression to this view. F.C. Wolff in 1759 championed it in opposition to the preformationist Haller. Modern researches on the cell and the changes of the chromatin matter of the nucleus have placed the two hypotheses in a new light. Weismann at first supported strongly, and now opposes it; O. Hertwig supports it in a modified form.

Literature: J. HARVEY, Exercitationes de Generatione; F. C. WOLFF, Theoria Generationis; A. WEISMANN, Germ-Plasm (1893); O. HERTWIG, The Biol. Problem of To-day (trans. by P. C. Mitchell, 1896); WHITMAN, Evolution and Epigenesis, Wood's Holl Biol. Lects. (1894); DRIESCH, Analytische Theorie d. organischen Entwicklung (1895); DELAGE, La Structure du Protoplasma et l'Hérédité (1895). For a summary of recent views see E.B. WILSON, The Cell in Devel. and Inheritance, where full reference to the literature of the subject will be found. (C.LL.M.- E.B.P.)

Epiglottis [Gr. epi + glwttiV, mouth of windpipe]: Ger. Kehldeckel; Fr. épiglotte; Ital. epiglottide. A plate of yellow elastic cartilage, in man shaped like an obovate leaf, attached in front of the superior opening of the larynx.

Ordinarily it stands up behind the base of the tongue; but in the act of swallowing, it probably falls back over the vocal cords and assists in preventing the entrance of solids or liquids into the trachea. Swallowing, however, may be performed normally with the epiglottis absent, the sphincter muscles of the larynx being sufficient to protect its aperture. According to some an important function of the epiglottis consists in toning the voice, raising the pitch by pressing down upon, and thus shortening, the vocal cords (Ellis), at the same time acting as a reinforcing vibration. Cf. SPEECH AND ITS DEFECTS. (C.F.H.)

Epilepsy [Gr. epi + lambanein, to take, seize]: Ger. Fallsucht Epilepsie; Fr. épilepsie, haut mal, petit mal; Ital. epilessia, mal caduco. In its most general sense epilepsy denotes discharging lesions of the nervous system, which are paroxysmal in character, and accompanied by more or less serious disturbances of consciousness; specifically it denotes the most distinctive form of such neuroses, known as true, genuine, or idiopathic epilepsy.

History. Epilepsy was well known in ancient times, and was regarded as an infliction of the gods; hence the term morbus sacer, morbus divus. The term morbus comiialis is connected with the custom of adjourning the forum whenever any of its members was seized with an epileptic attack. Other terms suggestive of demoniac or astral origin were also used. The name 'falling sickness' was applied to epilepsy within recent times.

Nature. The contributions of Hughlings-Jackson have established the conception (first suggested by Todd) of epilepsy as the explosion or discharge of nervous energy mainly from centres in the motor area of the brain. The study of epileptic convulsions thus contributes to the knowledge of the localization of brain functions. Such evidence is most clearly obtained in cases of epileptiform seizures, or Jacksonian epilepsy, in which the convulsions always begin in the same part of one side of the body, extending from this in a definite order of progression, first to other groups of muscles on the same side, and then to the opposite side (see below). The view which regards epilepsy as a central motor discharge with ultimate relations to the several layers of nerve-cells in the cortex, to the several levels of evolution of motor faculty, to the loss of consciousness, to the nature and order of the aurae, &c., does not deny the existence of epilepsy as the result of a discharge in the medulla and pons, and the possibility of a convulsive centre (in the medulla), stimulation of which in animals may produce convulsions; but it subordinates these phenomena to the chief and typical ones which in man are of cortical origin.

Cause. Many and various conditions are influential in the production of epileptic fits. Hereditary disposition is regarded as most important, the epileptic tendency being not so much a specific disease as the mark of an unstable condition of the brain. An hereditary taint may be discovered in more than one-third of all cases. Such taint may appear in one member of a family as insanity, in another as a nervous disorder, in a third as hysteria, and in a fourth as epilepsy. The epileptic tendency is thus recognized as a significant mark of degeneration, and its prevalence among criminals (see CRIMINOLOGY) has been frequently noted. Age is an important factor, nearly one-half of all cases appearing between the 10th and 20th year, and nearly 30 per cent. before the 10th year. Of specific exciting causes may be cited: injury to the brain by concussion, exposure to the sun, acute diseases, digestive derangements, alcoholism, menstrual disorders, sudden fright or similar emotional disturbance, and the like; but in a third or a half of all cases no definite exciting cause may be assigned. The disorder is thus mainly a functional one, brought about by a general instability of the nervous system and, possibly, more immediately connected with an irritation in the motor area, such as that produced by a tumour, depressed bone, anaemia, disturbance of circulation, or definite injury.

Morbid anatomy. A great variety of pathological changes have been found in cases of epilepsy, many of which are also common in other diseases. Negative cases presenting no serious pathological changes are quite common. Most frequent and characteristic are degenerative changes in the brain cortex, morbid changes in the skull and membranes, a simple type of convolution, asymmetry of the hemisphere. A special tendency to disease of the cornu Ammonis has been emphasized by some writers. None of these changes are sufficiently common to be regarded as essential, and all of them have been regarded as secondary or resultant; thus again bringing into prominence the theory of a functional instability accompanied frequently by degenerative changes, as the essential cause of the epileptic attacks.

Varieties. It is customary to distinguish the major attacks (grand mal), in which there is a loss of consciousness, and prolonged and severe muscular spasm, from the minor attacks (petit mal), in which there is brief loss of consciousness without or with slight muscular spasm. In Jacksonian epilepsy there is no loss of consciousness, but a definite 'march' of convulsive symptoms. In masked epilepsy (épilepsie larvée) the convulsions are replaced by mental symptoms, of which automatism is the most usual. A large number of varieties are also recognized, according to the diseases which accompany the epilepsy (gastric, spinal, &c.); according to the time when the fits appear (diurnal, nocturnal); according to the members involved in the fits (partial, monospasm, &c.); according to the supposed cause (vasomotor, cortical); and so on. Hystero-epilepsy is specially considered under HYSTERIA (q.v.).

Symptoms. These may be considered (Ross) as (1) those preceding the paroxysm, (2) those of the paroxysm itself, and (3) those observable in the intervals between the attacks. (1) One class of premonitory symptoms may appear hours, or even days, in advance in the form of headache, dizziness, depression, excitement, mental confusion, or the like. But the more constant premonitory symptoms, called aurae, immediately precede the attack, and may be said to be the subjective feelings aroused by the changes in the brain which bring on the attack. Such aurae are limited to the period before unconsciousness ensues; hence those who rapidly pass into unconsciousness (about half of all cases) will be unable to describe the aura. Such aurae are extremely variable in type, although often quite constant in the successive attacks of the same individual. The aura may be motor (twitching of the thumb, rotation of the eyes, jerking of the muscles); sensory (tingling, numbness, flashes of light, sharp noises, bad odours or tastes); vasomotor (dizziness, flushing, choking); secretory (salivation); psychical (fear, feeling of confusion or strangeness, hallucinations of forms or voices). The unilateral or bilateral location of the motor and sensory aurae, the frequency with which they begin in small muscles, the order in which they spread to other muscles, have been interpreted as indicative of the portion of the cortex at which the discharge begins, and of the direction in which it proceeds; thus, when the attack begins in the head, the order is head, arm, leg; when in the hand, the order is hand, head, leg; when in the leg, the order is leg, arm, head; such order indicating an extension of the discharge into neighbouring cortical centres.

(2) In the minor attacks of epilepsy (epilepsia mitior or petit mal) there is momentary unconsciousness, a slight pallor or vertigo; possibly a contraction of the pupils, a fixed stare, a rolling of the tongue, chewing movements, and the like. The patient may be speaking, pause, exhibit the symptoms of the attack, and proceed as if nothing had happened. At the onset of major attacks (epilepsy in the special sense, epilepsia gravior or haut mal) there is loss of consciousness, sudden falling, great pallor, and (usually) a sharp cry. The patient then exhibits a brief stage of tonic but unequal contraction of all the muscles of the body. There may be distortions of all kinds, rotation of the head and neck, flexion of hand, arm, &c. This tonic stage gives way to a clonic stage, with spasms usually more marked on one side, and the face or tongue usually affected before the trunk or leg. The head may be drawn from side to side, the eyeballs rolled about, the face distorted, the jaws violently clinched; there may be frothing at the mouth, and excess of secretions in general. In this stage the pallor has been succeeded by venous hyperaemia, the face being dull-red, the veins of the head and neck distended and throbbing. Upon this succeeds a stage of relaxation, exhaustion, or coma with gradual returning consciousness. There is often a long period of diminished energy and mental confusion. In Jacksonian epilepsy (epileptiform seizures) there is slight or no loss of consciousness, and the spasm begins on one side and proceeds in definite order; i.e. if it begins in the hand, it goes up the arm and down the leg. The more sudden the onset of the spasm the more rapidly it spreads, and the shorter the seizure. The seizures may be very frequent. In masked epilepsy the symptoms are of a totally different type, the convulsion being replaced by an abnormal psychosis of which the patient may be entirely ignorant upon returning to consciousness. Anger or violence may be the prevailing symptom, and severe injury may be inflicted on others by an epileptic in this state; or there may be an altered speech or personality, or a series of automatic acts.

(3) In the interval between the seizures many epileptics are perfectly normal in every respect; and noted historical cases of men of ability subject to epilepsy belong to this class. In many cases there is impairment of memory, especially in regard to recent events; in others there may be a dullness or mental deficiency, differing in amount from slight stupidity to imbecility. The moral nature is often perverted, and the temperament morose, suspicious, and irritable. Such mental impairment is quite as common in the minor as in the major forms of epilepsy, and, while related to the frequency of the seizures, it is also related to the prevalence of mental rather than motor symptoms during the attacks.

Epilepsy and Insanity. While epilepsy is entirely compatible with normal mental action, the tendency of frequent fits, extending over many years, to impair the faculties, to dull the finer feelings, and to change the character is a most potent one. Apart from the decay of faculty and dementia to which epileptics are subject, there are recognized distinct relations between epilepsy and insanity. The two may be viewed as effects of a common cause; or the brain degeneration which the explosive discharges bring about may be regarded as the exciting cause of the insanity. Epileptic insanity is apt to assume the form of mania, characterized by irritability and impulsiveness; in such states crimes and assaults have frequently been committed, and have given rise to serious discussions regarding mental responsibility (Maudsley, Responsibility in Mental Disease). The mania may occur just after the paroxysm, or it may occur between paroxysms, or take the place of the paroxysm, as in masked epilepsy. The term furor epilepticus was often used in connection with these violent outbreaks of epileptics. Periods of automatism and unconscious action in epileptics may also be regarded as significant in this connection.

Literature: BINSWANGER, Die Epilepsie, in Nothnagel's Spec. Pathol. u. Ther., xii (1899); GOWERS, Epilepsy (1881); FÉRÉ, Les Épilepsies et les Épileptiques (1890); ROSS, Nerv. Diseases, ii. 885-920; J. HUGHLINGS-JACKSON, Epileptiform Convulsions, &c., Trans. Int. Med. Cong. (1881), ii. 6, and Croonian Lectures on Evolution and Dissolution of the Nervous System, Brit. Med. J. (Mar. 29, Apr. 5 and 12, 1884); RONCOVONI, L'Epilessia (1895); GÉLINEAU, Les Épilepsies (1900). See also BIBLIOG. G, I, g. (J.J.)

Epiphany [Gr. epi + fainein, to bring to light]: Ger. Epiphania (Erscheinung Christi); Fr. Épiphanie; Ital. Epifania. The festival of the manifestation of God through Christ to mankind. It was first observed by the Eastern Church, which maintained that the manifestation took place at baptism, not at birth. The festival was celebrated on January 6. In the Western Church, Epiphany was never connected with the baptism, but with the manifestation of Christ to the Wise Men from the East, who were regarded as the 'firstfruits of heathendom' for Christ.

Literature: BINGHAM, Origines, Bk. XX. chap. iv; AUGUSTI, Handb. d. christl. Archäol., i. 542 f.; BINTERIM, Denkwürdigkeiten, v. Pt. I. 310 f. (R.M.W.)

Epiphenomenon [Gr. epi + fainomai, to appear]: Ger. Beiprodukt, Begleiterscheinung; Fr. épiphénomème, (quelque chose) surajouté; Ital. epifenomeno. A secondary or added accompaniment to a process, considered as merely incidental, and having no part in the further development of the process.

The term is in use mainly to characterize the Epiphenomenon Theory of the relation of mind to body, which makes the former an incidental effect of brain processes -- 'a spark thrown off by the engine' -- having no effect upon the brain changes which constitute a closed system. See MIND AND BODY. (J.M.B.)

'The addition of consciousness to living bodies affords no ground for supposing that consciousness has a causality of its own, or reacts upon the organism in which it appears (Hodgson, Theory of Practice, i. 425). According to the same writer, the theory conceives consciousness 'in some such way as the foam thrown up by and floating on a wave' -- 'a mere foam, aura or melody, arising from the brain, but without reaction upon it' (Time and Space, 279). An early psychological statement is by Maudsley, Physiol. and Pathol. of Mind. (A.S.P.P.- J.M.B.)

Epiphysis [Gr. epi + fusiV, a growth]: Ger. Zirbeldrüse; Fr. épiphyse, glande pinéale; Ital. epifisi, ghiandola pineale. See BRAIN, and cf. PARIETAL ORGAN. Synonyms: Pineal gland, Conarium. (H.H.)

Epistemology [Gr. episthmh, knowledge, + logoV, discourse]: Ger. Erkenntnisstheorie; Fr. épistémologie; Ital. gnoseologia, dottrina della conoscenza. (1) Theory of the origin, nature, and limits of knowledge. Cf. GNOSIOLOGY. (H.R.S.- J.M.B.)

(2) The systematic analysis of the conceptions employed by ordinary and scientific thought in interpreting the world, and including an investigation of the act of knowledge, or the nature of knowledge as such, with a view to determine its ontological significance; otherwise known as Theory of Knowledge.

The first definition of epistemology, commonly spoken of as the relation of knowledge to reality, has hitherto been most prominent, and epistemological inquiry has generally been undertaken in view of doubts which have been raised as to the trustworthiness of the knowing process, and the validity of its results. It is thus, as Paulsen well points out, a secondary, not a primary product of thought. 'Philosophy began everywhere with metaphysics; questions as to the form and origin of the universe, the nature and source of existence, the essence of the soul and its relation to the body, form the first subject of philosophical reflection. Only after long occupation with such questions does the question arise of the nature of knowledge and its possibility. It is raised by the divergent views to which meditation on physical and metaphysical questions leads. This divergence raises the question: Is it at all possible for the human understanding to solve these problems? Epistemology develops as critical reflection upon metaphysics' (Einleitung in die Philos., 2nd ed., 349). Thus, in ancient philosophy, the Sophists may be said to be the first definitely to raise the epistemological question, by their sceptical impeachment of the possibility of truth or universally valid statement. This is the epistemological issue which is mainly discussed by Plato and Aristotle, but it is found (cf. for example the Theaetetus) to involve the question of the constitution of knowledge, as debated between sensationalists and rationalists, empiricists and transcendentalists. But such questions are discussed by Plato and Aristotle in the context of their metaphysical and more purely logical inquiries. The epistemological problem comes more into the foreground as a separate investigation, in consequence of the systematic attack on the possibility of knowledge by the Sceptics. The discussion of 'the criterion of truth' by the Stoics and Epicureans is a conscious and deliberate attempt to arrive at a theory of knowledge, as a preliminary to metaphysical construction. The theory of Probabilism, developed by the Sceptics of the later Academy, is an outcome of the same discussions.

In modern times, epistemology first steps into the foreground with Locke, whose Essay, according to its author's own account, had its origin in 'the difficulties that rose on every side' in the course of a metaphysical discussion. Whereupon, says Locke, 'it came into my thoughts that we took a wrong course, and that, before we set ourselves upon inquiries of that nature, it was necessary to examine our own abilities, and see what objects our understandings were or were not fitted to deal with' (Epistle to the Reader). In the introductory chapter he emphasizes in similar language the necessity of a theory of knowledge as a preliminary to metaphysical inquiry. 'Till that was done,' he continues, 'I suspected we began at the wrong end. . . . Extending their inquiries beyond their capacities, and letting their thoughts wander into those depths where they can find no sure footing, it is no wonder that men raise questions and multiply disputes which, never coming to any clear resolution, are proper only to continue and increase these doubts, and to confirm them at last in perfect scepticism. Whereas, were the capacities of our understandings well considered, the extent of our knowledge once discovered, and the horizon found which sets the bounds between the enlightened and the dark parts of things -- between what is and what is not comprehensible by us -- men would perhaps with less scruple acquiesce in the avowed ignorance of the one, and employ their thoughts and discourse with more advantage and satisfaction in the other' (I. i. 7). The design of the Essay is, accordingly, in his own words, to inquire into 'the certainty, evidence, and extent' of our knowledge, and at the same time 'to search out the bounds between opinion and knowledge, and examine by what measures, in things whereof we have no certain knowledge, we ought to regulate our assent and moderate our persuasions' (I. i. 3). In these and other similar passages Locke impressed upon succeeding English philosophy its predominantly epistemological character. It will also be noted that they express the epistemological question in its characteristically modern form, as referring to the limits of human knowledge -- the form in which it meets us in Hume and Kant, Comte and Spencer. Kant's description of dogmatic metaphysics as the arena of endless contests, comparable to the shadow-fights of the heroes in Walhalla, and his idea of criticism' as the science which is to determine 'the extent, validity, and worth' of our a priori cognitions, and thus to settle the question as to the possibility or impossibility of 'metaphysics,' repeat almost verbally Locke's conception of his own enterprise, though the execution in the two cases is of course different. Repeating Locke's metaphor, Kant blames Hume for declaring certain questions to lie beyond the 'horizon' of human knowledge, without determining where that horizon falls. 'He (Hume) merely declared the understanding to be limited, instead of showing what its limits were; he created a general distrust of the power of our faculties, without giving us any determinate knowledge of the bounds of our unavoidable ignorance.' As contrasted with scepticism, criticism does not 'examine the facta of reason, but reason itself in the whole extent of its powers, and in regard to its capacity of a priori cognition; and thus we determine, not merely the empirical and ever-shifting bounds of our knowledge, but its necessary and eternal limits' (see Critique of Pure Reason, Preface to First Edition, Introduction, and Transcendental Doctrine of Method, chap. i).

This way of stating the epistemological question entirely disappears in Kant's idealistic successors. The philosophy of Fichte and Hegel (especially in the Wissenschaftslehre and the Logik) may be said to consist largely of an analysis of cognition and the categories of thought, but no distinction is drawn between theory of knowledge and metaphysics. After the philosophical interregnum, however, which followed the collapse of the Hegelian school in Germany, the 'return to Kant' which began between 1860 and 1870 once more placed Erkenntnisstheorie in the centre of philosophical interest. The multiplication of Neo-Kantian treatises on this subject had proceeded so far, in 1878, as to call forth Lotze's protest against, 'the constant whetting of the knife,' which, he says, 'becomes tedious if it is not proposed to cut anything with it.'

The conception of epistemology which is thus traceable directly to Locke and Kant is open to certain fundamental objections. Locke himself errs by supposing that the first objects of knowledge are the subjective states of the individual mind. He conceives the problem to be: How is the passage legitimated from states of consciousness to external or trans-subjective reality? But this is to invert the real process of knowledge. States of consciousness are not known as objects, except to the psychologist, and, when so known, they are known as elements in a real world, and in contrast to the world of external or physical reality. The notion of reality or of object is, therefore, prior to the distinction between external and internal, i.e. between objective and subjective in the popular use of these terms. Accordingly, a start cannot be made in the analysis of knowledge from the individual knower, conceived as enclosed and isolated within the circle of his own mental states. Then, again, it is impossible to criticize the validity of knowledge, as it were ab extra, in the Kantian manner. It is obvious that we cannot sit in judgment upon our cognitive faculties without employing those very faculties, and thereby implying their trustworthiness. The validity of knowledge as such is an ultimate and inevitable assumption, and Hegel's well-known comparison of Kant's procedure to the resolve of Scholasticus not to enter the water till he had learned to swim, crystallizes in an epigram the contradiction involved in the attempt to determine whether the world of knowledge is merely subjective (phenomenal), or gives us things as they are. Kant's results, in this reference, really rest upon his attribution of certain elements in knowledge -- the universal elements of time, space and the categories -- to the subject, and certain others -- the particularity of sense -- to the object: and this in turn rests upon the confusion between epistemology and psychology which still disturbs his treatment, and leads him to identify a priori, or necessary in knowledge, with what is subjective or innate in the individual mind.

But if criticism of knowledge in the Lockian and Kantian sense must be abandoned, the need of a theory of knowledge still remains. Its use is, in the first instance, polemical, in answer to the challenge of scepticism, subjectivism, agnosticism, relativism. In this regard, it is the province of epistemology to investigate the nature of the cognitive relation as such, in order to discover its essential conditions, and so to determine whether the circumstances of human knowledge are such as to invalidate its claim to be a true account of reality. An agnostic relativism condemns knowledge because it does not satisfy certain conditions. By exposing the inherently contradictory nature of the demands made, epistemological analysis deprives such criticism of its basis, and restores us to the original confidence of reason in itself. Till scepticism and agnosticism cease from the land, this polemic will necessarily continue to be prominent in epistemological literature, whichever side may win the greater body of adherents. As matter of history, the questions of epistemology in this reference are conveniently tabulated by Külpe (Einleitung in die Philos., 119-20) as follows: --

(1) The question of the origin of knowledge, giving rise to the opposing views of the rationalists and empiricists (or sensationalists), and the mediating position of Kantian criticism; (2) the question of the validity and the limits of knowledge, giving rise to the variety of positions expressed by such terms ad dogmatism, scepticism, relativism, positivism; and (3) the question of the nature of the objects of knowledge, as subjective or trans-subjective, giving rise to the opposition of idealism and realism. But the three questions merge into one another.

Apart from such controversial issues, epistemology is sometimes held to include, as indicated in the second definition, an analysis of knowledge in the widest sense -- a critical analysis of all the conceptions by which we endeavour to interpret the world. This 'criticism of categories,' as it has been called, does not involve the larger enterprise of Kant. It is an objective or, as Hegel called it, a disinterested analysis, which, by making clear the precise significance of each conception and the sphere of its application, allows the one, as it were, to judge and supersede the other. The result of the analysis is consequently the recognition of 'degrees of truth' (or conversely, degrees of 'abstraction') in the representations of the world which arise from the application of different conceptions. Kant's table of the categories and Hegel's Logik are contributions to such a Kategorienlehre, or immanent criticism of thought. In more recent times, epistemology finds perhaps its most important function in a criticism of the assumptions involved in the methods and fundamental conceptions of the different sciences. Ward has more than once urged that this is 'the chief business of philosophy' (cf. Mind, O.S., viii. 153 and xv. 213). The general result of such a philosophical criticism of science must necessarily be to show that the accounts given of the world by the different sciences are essentially dependent on the abstractions or assumptions on which these sciences proceed. And in proportion as this insight is reached, these accounts are forced to surrender their pretensions to final or absolute truth; they are seen to be only aspects of experience, possessing relative truth in a greater or less degree.

[Such procedure was made explicitly the method of metaphysics by Herbart -- his 'rectification of conceptions' -- and was employed with great force by Lotze. Cf. HERBARTIANISM. (J.M.B.)]

Epistemology requires to be distinguished from the psychology of cognition, and it is also commonly distinguished from metaphysics or ontology and from logic. A few words on these distinctions may serve to give greater precision to the foregoing account of the scope and function of epistemology.

The distinction between psychology and epistemology is embodied in the Cartesian distinction between the esse formale seu proprium of an idea, regarded only as a specific mode of consciousness, and its esse obiectivum sive vicarium, when it is taken in its representative capacity, as standing for some object thought of. The psychologist deals with psychical events merely as such -- as facts connected with and dependent on other facts. The interconnections of this factual world -- the laws of the happening of psychical events -- are what the psychologist has to investigate. In perception, for example, he is concerned, as Sully puts it, 'with the genesis and development of our perceptions as subjective or psychical processes having certain physiological concomitants,' but not with 'the objective import and validity of the result.' Croom Robertson suggested (Mind, O.S., viii. 15) that, in view of this difference of standpoint, the word knowledge might be conveniently banished from psychology, and its place taken by the more colourless term intellection; just as Ward says that the traditional 'Cartesio-Lockian idea,' which is essentially an epistemological term, might be replaced in psychology by the phrase state of consciousness. In brief, psychology, although dealing in popular parlance with the subjective, treats these subjective facts, like any natural science, as an objective world in which it traces causal connections, concomitances, or sequences, and the evolution of the more complex from simpler formations. But it does not analyse the subject-object relation which constitutes knowledge as such, and which is the presupposition of psychology as well as of every other science. To analyse this relation and its implications is the specific task of epistemology.

Epistemology is usually distinguished from ontology or metaphysics in the narrower sense of that term. Philosophy, in other words, is defined as 'a theory of knowing and being,' and epistemology and ontology are regarded as the two complementary inquiries into which it falls. The two inquiries are, however, so closely allied that it is impossible to carry on either independently and (for example) to treat epistemology, as Locke apparently intended, as entirely 'preliminary' to metaphysics. Some, accordingly, have refused to make any distinction between the two. But the analysis of knowledge, though involving fundamental ontological conclusions, cannot give us all that is included under metaphysics or ontology, regarded as a synthetic statement in ultimate terms of the nature of reality. This statement must be based not only upon the structure of knowledge, but upon ethical and aesthetic considerations, upon our notions of value, and the relation of our ideals to the ultimate ground of reality.

The variations of current usage in regard to the scope of logic make it difficult to formulate any generally recognized distinction between logic and epistemology. Some would identify the two, while others would prefer to include epistemology as a branch of logic in a generalized sense. It is certainly true that the best logical treatises of the present day, such as those of Sigwart, Lotze, Bradley, Bosanquet, Wundt, contain a great deal of properly epistemological matter. But although the traditional logic of the textbooks cannot claim the unity of an independent science -- being, in fact, an amalgam of elements from different sources, such as grammar, psychology, and metaphysics -- still, the usage which defines logic as the science of the formal principles of thought -- the exposition of the laws of formal consistency in passing from one statement to another -- appears too firmly established to make successful innovation probable. Cf. LOGIC, and EMPIRICAL LOGIC.

Literature: the term epistemology appears to have been first made current by FERRIER in his Institutes of Metaphysics (1854). Works on philosophy, and BIBLIOG. B, i, d. In German there is a department of literature devoted to Erkenntnisstheorie. (A.S.P.P.)

Episyllogism: Ger. Episyllgismus; Fr. épisyllogisme; Ital. episillogismo. A syllogism of which one (or both) of the premises is stated as the conclusion of another syllogism. The latter is called technically a prosyllogism. See CHAIN ARGUMENT, and SYLLOGISM. (R.A.)

Epithelium [Gr. epi + qhlh, a nipple or papilla]: Ger. Epithel; Fr. épithélium; Ital. epitelio. Cellular covering of free surfaces of the body and of all natural cavities which open, either temporarily or permanently, to the exterior; also applied to lining of serous, lymphatic, and vascular channels and cavities which do not open to the exterior. Cf. ENDOTHELIUM.

The term was originally used of the mucous membrane of the lips and mouth, where the etymological significance of the word is plain. (C.F.H.)

Equality [Lat. aequus, equal]: Ger. Gleichheit; Fr. égalité; Ital. eguaglianza. (1) Consciousness of: the discernment of lack of difference between two experiences in respect to QUANTITY (q.v.) or NUMBER (q.v.). (2) Notion or concept of: the thought of lack of difference in quantity or number in general.

The meaning given first is genetically earlier, and arises probably with the treatment of things in groups of greater or less size, either (a) by reaction upon the groups as wholes, with varying results, (b) by establishing one to one correspondence among the parts, or (c) by measurement: the three processes occurring genetically in the order given. When by any of these processes disparity or difference is discovered, the consciousness of equality arises over against that of difference. It is this antithesis with difference or inequality that distinguishes equality from identity. After the number concept is further developed -- this consciousness of equality and inequality being its first stage (see NUMBER CONCEPT) -- the numerical distinctness of the two or more experiences is consciously recognized, and the direct comparison is made. This use of comparison with ABSTRACTION (q.v.) gives the second meaning, in which equality is an abstract idea.

In mathematics and symbolic logic the symbol of equality is ( = ), and the formula of equality ( A = A ) is called an equation. (J.M.B.)

Equality (social). (1) Practical equivalence of social rank, consideration, and enjoyment of opportunities that are created by society or the state. (2) A social shibboleth of revolutionary origin in France -- 'Liberty, Equality, Fraternity.'

Matthew Arnold, essay on Equality, gives credit to Menander for the first serious advocacy of equality as a social condition. It was Rousseau, however (Du Contrat Social and Émile), who created a popular enthusiasm for equality as an ideal. William Godwin (Political Justice) and Jeremy Bentham (Morals and Legislation) were the first serious advocates of equality in English political literature. Fitzjames Stephen's Liberty, Equality, and Fraternity is a destructive criticism. Matthew Arnold's essay is a plea for social equality. W. C. Brownell's French Traits is a psychological study of actual social equality in France. Giddings (Elements of Sociology) has argued that liberty presupposes fraternity, and fraternity a practical equality. (F.H.G.)

Equation: see EQUALITY.

Equilibrium: see ORIENTATION (1).

Equilibrium (in aesthetics): see BALANCE.

Equilibrium (illusions of): see ILLUSIONS OF MOTION AND MOVEMENT.

Equilibrium (in biology): see ACCOMMODATION.

Equilibrium (in economics) [Lat. aequus, equal, + libra, a balance]: Ger. Gleichgewicht; Fr. équilibre, indifférence; Ital. equilibrio economico. Such a set of conditions with regard to the amount and distribution of wealth, that the motives for an increase of any particular kind of wealth exactly balance the motives against such an increase.

Thus a market price establishes itself at a point of equilibrium where the demands of those who are willing to buy at that price or a higher one exactly equal the supplies offered by those who are ready to sell at that price or any lower one. If the price is higher, the supply exceeds the demand, and tends to drive the price down; if it is lower, the demand exceeds the supply, and tends to force the price up.

The equilibrium here described is a static one; it deals with quantities and not with rates. The attempt to establish a point of dynamic equilibrium or normal price, where rates of production and consumption shall be equal, is far more complex and uncertain. (A.T.H.)

Equilibrium (in physics): Ger. Gleichgewicht; Fr. équilibre; Ital. equilibrio. The state of a body which is free to move, and acted on by forces so related that they neutralize each other, so that the body has no tendency to move. In order that a system of forces may produce equilibrium, the resultants of the forces, both that of translation and that of rotation, must vanish.

If the forces producing equilibrium are such that when the body acted on is slightly displaced it tends to return to its place, the equilibrium is called stable; if it tends to move still further from the position, it is called unstable; if the equilibrium remains undisturbed, it is called indifferent or mobile. If a wheel free to turn on a horizontal axis has a weight attached to its rim, it is in stable equilibrium when the weight is directly below the axis; in unstable, when the weight is vertically above the axis. (S.N.)

Equilibrium (sensation of): Ger. Empfindung des Gleichgewichts; Fr. sensation d'équilibre, sens de l'équilibre; Ital. senso dell' equilibrio. The sensation arising from the erect balancing of the body. Its existence is in evidence principally when it is disturbed. (J.M.B.)

The 'sense' of equilibrium is apparently built up from the muscular, cutaneous, and pressure senses, and from visual perception. At the same time there seems to be no doubt that the semicircular canals of the ear (see STATIC SENSE, also for literature) arouse and sustain a permanent muscular tone, which contributes greatly to the maintenance of equilibrium. The growth of the necessary associations may be observed in the child learning to hold the head erect. Cf. DIZZINESS. (E.B.T.- J.M.B.)

Equipollence or -cy [Lat. aequus, equal, + pollere, to be able]: Ger. Aequipollenz; Fr. équipollence; Ital. equipollenza. The relation between two propositional forms which represent the same fact. It translates the Gr. isodunamwn. (C.S.P.)

There has been a twofold tradition on the nature of equipollence: one, as stated above, restricting it to the qualitative; the other extending it to all cases in which two propositions, formally different, must be true or false together. The one tradition goes back to Apuleius (see Prantl, Gesch. d. Logik, i. 583), the other to Galen (see id., i. 568-9). As illustrating the one, see Wallis, Logica, Lib. II. cap. vi; for the other, see Crackanthorpe, Logica, Lib. III. cap. iv. Cf. Ueberweg, Logik, § 96. Recently the term has fallen into desuetude, and its place tends to be taken by Obversion. (R.A.)

Equity (in law) [Lat. aequitas]: Ger. (1) Billigkeit, (2) Gerechtigkeit; Fr. (1) équité; Ital. equità. (1) Justice; that which is ex aequo et bono. (2) The system of remedial justice administered by courts of Equity, or (what is synonymous) courts of Chancery. (3) The kind of remedy afforded by that system. It is one circumscribed by precedent, and not always identical with natural equity.

The rigid forms in which legal remedies are encased, and by which legal rights are practically determined, in early societies, gradually give way to methods of procedure based more on reason and leaning more to substance of right. Strict law is thus harmonized with or modified into equity. The Roman praetors, at the instance of the Roman lawyers, by the annual praetorian edict, brought about this change at Rome. In England it was initiated by the lord chancellor, as the keeper of the king's 'conscience,' and soon produced a system of judicial procedure known as chancery, administered by separate courts of Chancery. These courts often interposed to prevent the use of a legal advantage gained in the ordinary law courts, as by enjoining a judgment creditor against enforcing a judgment which he had obtained under such circumstances as to make it inequitable for him to use it. They also gave a remedy, when there was no adequate one, at law. In the United States a similar division of lawsuits, between actions at law and actions in equity, formerly existed in most states, and now exists in the Federal courts. In England, and in many of the United States, the distinction was abolished during the latter half of the 19th century. Cf. CODE.

Literature: POMEROY, Equity Jurisprudence, i. chap. i; SOHM, Instit. of Roman Law, § 13; MAINE, Ancient Law, chaps. ii, iii. (S.E.B.)

Equivalence (law of): see CONSERVATION OF ENERGY, for which it is sometimes used. (J.M.B.)

Equivocal [Lat. aequus, equal, + vox, voice]: Ger. mehrdeutig, zweideutig; Fr. équivoque; Ital. equivoco. Terms are 'equivocal' when with identity of verbal expression there is difference of meaning, and they may therefore stand for wholly distinct notions or things. (R.A.)

Equivocation: Ger. Zweideutigkeit; Fr. équivoque; Ital. equivoco. The use of an expression capable of two meanings, one false and the other true, for the purpose of suggesting the false meaning to the hearer without committing the speaker to that meaning.

On the morality of equivocation there is no little diversity between common opinion and moral principle. In a lie or falsehood it is common to distinguish (1) the objective discrepancy between the statement and the facts, called material falsehood; and (2) the intention to deceive, called formal falsehood. The moralist, who looks to the intention of the agent as determining right and wrong, is accordingly led to regard the formal falsehood as that, and that only, which is essentially contrary to morality. And formal falsehood is present in the equivocation as much as in the lie -- from which equivocation is only distinguished by the absence of material falsehood. See, however, the further distinction between 'positive' and 'negative' misrepresentation under LIE.

On the other hand, the external treatment of morality which distinguished the casuistical moralists (see CASUISTRY) made it easy to defend equivocation and to distinguish it from lying. Thus Sanchez, quoted by Pascal (Lett. prov., ix), says: 'It is permitted to use ambiguous terms so that they may be understood in a different sense from that in which one understands them oneself.' On the same ground permission is given to mental reservation (restriction mentale): 'One may swear that one has not done a thing which one has really done, by saying within oneself that one did not do it on a certain day, or before one was born,' or even 'after having said aloud "I swear," one may add to oneself "that I say," and then continue aloud "that I did not do that."' 'And this is very convenient in many circumstances, and always quite correct when necessary or useful for health, honour, or happiness.' (W.R.S.)

Erastianism: Ger. Erastianismus; Fr. Érastianisme; Ital. Erastianismo. Generally stated, Erastianism means the supremacy of the civil authority in ecclesiastical as well as in civil causes.

This politico-ecclesiastical doctrine derived its name, though not its entire contents, from Thomas Erastus, professor of medicine at Basel in 1580. He was opposed to anything in the nature of a theocratic church. His doctrine was espoused by such members of the Westminster Assembly as Selden, Coleman, and Lightfoot.

Literature: THOMAS ERASTUS, Explicatio quaestionis gravissimae utrum excommunicatio, &c. (Eng. trans. by Lee); Subordinate Standards of the Free Church of Scotland (the Claim of Right and Protest); BUCHANAN, Ten Years' Conflict; HANNA, Life of Chalmers; WALKER, Dr. Robert Buchanan; Free Church of Scotland, Annals of the Disruption. (R.M.W.)


Eratosthenes. (276-194 B.C.) A Greek philosopher and astronomer, noted for his learning. Bunsen ranks him next to Aristotle, adding that he is 'as far superior to him [Aristotle] in extent of learning as inferior in grasp of intellect.' He was a pupil of Callimachus, and librarian in the great Alexandrian library.

Erdmann, Johann Eduard. (1805-92.) Born at Wolmar, Livonia; studied at Dorpat and Berlin; became professor of philosophy at Halle in 1836, and died at Halle.

Erethism [Gr. ereqismoV, irritation]: Ger. Erregungszustand; Fr. éréthisme; Ital. eretismo. An exaggerated degree of irritability in a part of the body; applied frequently to an irritable condition of the brain and nervous system. (J.J.)

Eretria (school of): see PRE-SOCRATIC PHILOSOPHY.

Erg: see UNIT (of physical measurement).


Erhard, Johann Benjamin. (1766-1827.) A Berlin physician, who wrote on psychology, mental pathology, ethics, and jurisprudence. In his education he was much influenced by Shaftesbury, Moses Mendelssohn, J. H. Lambert, and, later, by Kant.

Erhardt, Simon. (1776-1829.) After 1809 a teacher at Schweinfurt, Ansbach, and Nürnberg; in 1811 professor of philosophy at Erlangen, and, later, at Freiburg; in 1823 professor of philosophy at Heidelberg. He belonged to the school of Schelling.

Erigena, Johannes Scotus. Born in Ireland between 800 and 815; died in the latter half of the 9th century -- place unknown. He was probably the keenest and most profound thinker of the 9th century. In 843 probably he went to France, where he enjoyed the patronage of Charles the Bald. He was the forerunner of scholasticism. He advocated the supremacy of reason, and maintained a vague Pantheism. Condemned as a heretic at Paris in 1209 for his writings on predestination and transubstantiation.

Eristic: see Megarians, under SCHOOLS OF GREECE (Post-Socratic).

Eros [Gr.]. The principle of love in NEO-PLATONISM (q.v.) and MYSTICISM (q.v.).

Erotomania or Eroticomania [Gr. erwV, love, + mania, madness]: Ger. Erotomanie; Fr. érotomanie; Ital. erotomania. A symptom of various mental troubles, characterized by a morbid and intense passion for the opposite sex; the sexual feeling is imaginative and emotional rather than carnal.

The term is also used to express excessive sexual passion, and thus becomes synonymous with nymphomania in women, and satyriasis in men. (J.J.)


Error of Mean Square: see ERRORS OF OBSERVATION.

Errors of Observation (theory of): Ger. Ausgleichungs - Rechnung; Fr. théorie des erreurs; Ital. teoria degli errori. A department of the theory of probability treating of the adjustment of measurements and quantitative estimates; called also method of least squares (Ger. Methode der kleinsten Quadrate; Fr. méthode des moindres carrés). The method was first used by Gauss (about 1795) and was first described by Legendre (1806).

When a magnitude is measured a number of times the determinations will differ, and when all the measurements are equally valid, their average is likely to be more nearly the true magnitude than any single measurement. The departures of the separate measurements from the true value are called errors, and their departures from the average are called residuals. As, however, errors and residuals will coincide theoretically when the number of experiments is large, the term error is often used to include residuals. There will be more small errors than large ones, and they will be distributed in a definite fashion given by the equation

y = ce-n2 x2,

and represented by the bell-shaped curve VYU.

In this curve the size of an error is represented by the abscissae OP, O U', &c., and its frequency by the ordinates OY, PQ, &c. The number of errors less than a given size is represented by the area of the curve above the abscissa. Thus one-half of all errors will be smaller than OP. This error is called the probable error. The mean of all the errors -- the mean error -- will be a little larger, ON; the error of mean square, where there is an inflection point on the curve, and where a few experiments give the most accurate results, is OS. The modulus is OL. If the probable error be 1.00, the mean error is 1.18, the error of mean square 1.48, and the modulus 2.10. The reliability of the average is inversely proportional to these errors, and proportional to the square root of the number of observations.

The theory of errors of observation is based on the assumption that each error is the result of a great number of small causes independent of each other and equally likely to make the measurement too small or too large. The theory as applied in physical science is not concerned with constant errors which it cannot eliminate. In psychology, however, the real magnitude is known in some cases, and the perception of judgment may tend to be on the average too large or too small. The difference between the true magnitude and the average of the measurements is the constant error, which may be positive or negative. The average departure from the true magnitude is called the average error in psychophysical work, while the average departure from the average is called the variable error. In certain time measurements the term 'mean variation' (M.V.) has been used by psychologists. This is identical with the mean error of physical science or the variable error of the psychophysical methods. This error or variation is found by taking the difference between each separate measurement and the average of them, and taking the average of these differences without reference to the signs.

These distinctions are important for the statistical treatment of VARIATION (q.v.) and for the study of the PSYCHOPHYSICAL METHODS (q.v.).

Literature: treatises on the subject were published in the same year, 1812, by GAUSS and LAPLACE. Useful works in English are AIRY, Theory of Errors of Observation (1861), and MERRIMAN, Method of Least Squares (6th ed., 1893). See also under VARIATION (statistical treatment of). (J.McK.C.)

Eschatology [Gr. escatoV, last, + logoV, word, reason]: Ger. Eschatologie; Fr. eschatologie; Ital. not in use. The section of dogmatic theology which -- as compared with theology proper, anthropology, and soteriology -- deals with the 'doctrine of the last things'; that is, with death, the future life, and the end of the world.

Jewish eschatology was essentially connected with the Messianic hope in its various developments, early Christian with the apocalyptic expectation of the Second Coming. Dogmatic eschatology, having direct reference to the conduct of the present life, was formulated during the supremacy of the mediaeval church. See CHILIASM, IMMORTALITY, and MESSIANIC HOPE.

Literature: LUTHARDT, Die Lehre v. d. letzten Dingen; ALGER, Doctrine of a Future Life (with very full literature); OXENHAM, Catholic Eschatology and Universalism; SPLITTGEBER, Tod, Fortleben u. Auferstehung; DAVIDSON, The Doctrine of Last Things; SALMOND, The Christ. Doctrine of Immortality; CHARLES, Hist. of the Doctrine of a Future Life in Israel, Judaism, and Christianity. (R.M.W.)

Esoteric and Exoteric [Gr. eswterikoV, exwterikoV]: Ger. esoterisch, exoterisch; Fr. ésotérique, exotérique; Ital. esoterico. Terms used to characterize two different presentations of doctrine with the Pythagoreans, Plato, and Aristotle. What was taught to their most advanced disciples was denominated esoteric; what was given to the pupils not in the inmost circle and to the outside world was called exoteric. The term exoteric is used by Aristotle to denote a treatment of a subject fitted to the ordinary reader; a meaning very close to that of our word 'popular.' (H.R.S.)

Esprit de Corps [Fr.]: Ger. Korpsgeist (Barth); Ital. spirito di corpo. The consciousness, on the part of a member of a social group, of the interests common to the group.

Defined sociologically, the effects or external evidences of this consciousness are meant. In either case the term interest is to be understood in the widest sense. The esprit de corps is a function of the social consciousness -- of consciousness having social interests -- and is to be accounted for in terms of the general principles according to which social life is reflected in consciousness. Cf. CONSCIOUSNESS OF KIND, SOCIUS, and (for literature) SOCIAL PSYCHOLOGY. (J.M.B.)

Essence [Lat. essentia, from esse, to be]: Ger. Wesen; Fr. essence; Ital. essenza. The constant and necessary nature of a thing as contrasted with its accidents. (H.R.S.- J.M.B.)

Aristotle uses the word for (1) the form, (2) the matter or substratum, (3) the concrete being, the individual. See FORM AND MATTER. But the scholastics defined the word more precisely in contrast with substance: essence is the nature of the individual thing, substance is the indeterminate substratum, which, united to the form, makes up the individual thing. Descartes follows the scholastic usage, but since his time the word essence has usually had the same meaning as substance. Kant defines essence as determined by an idea; hence it may be false to reality, while the nature of a thing is actually experienced and cannot be false. Cf. SUBSTANCE, NATURE, ATTRIBUTE, ACCIDENT. For citations see Eisler, Wörterb. d. philos. Begriffe, 'Wesen.' (H.R.S.)

Essenes [possibly Gr. osithV, holiness; possibly Heb. Chassidim, the pious]: Ger. Essener; Fr. Esséniens; Ital. Esseni. A Jewish sect.

Our knowledge of the origin, customs, and tenets of this sect is very imperfect. As a result, much conflicting conjecture has arisen. The primary sources are few and scanty; references, usually less rather than more extended, being made only by Philo of Alexandria, Pliny the Elder, Eusebius of Caesarea, and Josephus. On the whole, it seems probable that the Essenes were one of the many phenomena which resulted from the introduction of foreign, especially Hellenic, culture into Palestine. They were fanatics in their strict observance of the Mosaic law of ceremonial purity; yet they adored the sun, held non-Jewish beliefs about the soul, entertained Greek views regarding the future life, and advocated a doctrine of pre-existence not widely different from that of the Pythagoreans. Their points of contact with doctrines distinctive of the early Christian community have given rise to many conjectures, some having gone so far as to allege that John the Baptist and Jesus were Essenes. Yet they are not even mentioned in the Gospels.

Literature: the best brief account in English is that of F. C. CONYBEARE, in Hastings' Dict. of the Bible, art. Essenes; SCHÜRER, Hist. of the Jewish People in the Time of Christ, Div. II. ii. 188 f. (gives the literature fully); GINSBURG, The Essenes, their History and Doctrines; THOMSON, Books which influenced our Lord, 75 f.; MORRISON, The Jews under Roman Rule, 323 f.; CHEYNE, Origin of the Psalter, 418 f., 446 f.; COHN, in the Jewish Quart. Rev. (1892), 38 f.; FRIEDLÄNDER, Zur Entstehungsgesch. d. Christenthums, 98 f.; CONYBEARE, Philo about the Contemplative Life, 278 f.; HARNACK, Hist. of Dogma (Eng. trans.), i. 68 f., 243. (R.M.W.)

Essential (in logic): see QUANTITY, and TERM.

Essential Attitude: see ESSENCE.

Essential Co-ordination (of Avenarius): see INTROJECTION (passim), and for literature EMPIRIO-CRITICISM.

Esthesiogenic: see AESTHESIOGEN.

Esthesiometer (or Aesth-): see LABORATORY AND APPARATUS, II. B. (c), (3).