Classics in the History of Psychology
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Christopher D. Green
York University, Toronto, Ontario
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History of Psychology: A Sketch and an Interpretation
James Mark Baldwin (1913)
Philosophical Psychology -- Dualism, Rationalism, Dogmatism.
I. Descartes (1596-1650) -- It has already been intimated that René Descartes stands at the portal of the temple of modern philosophy and psychology. It is not by reason of absolute originality of view that he holds this position, but by reason of the explicit statement he gave to views, and the new synthesis he gave to thoughts, which had been stated before him only partially and in relative detachment. The essential advances which Descartes represents -- apart from the question of method -- are two, both of which we have had reason to refer to already.
In the first place, Descartes stands for the most explicit and uncompromising dualism between mind and matter. His position is not only clearly stated, but defended in detail. He distinguishes mind and body as two substances separate and incompatible. They have different properties, each its own specific characters or marks. The essence of body, he says, is "extension"; and the essence of mind is "thought." These two substances are known in different ways; they form the subject-matter of different scientific interests; they are investigated by different methods. The method of the physical sciences is mathematics. Here Descartes, the philosopher, opened up a new vista to modern [p. 109][figure][p. 110] thought. The method of psychology, the science of mind, on the contrary, is introspection, inner observation of the events of consciousness. It is in this last point that we come upon a second position by which Descartes gave a large measure of justification to modern psychology.
This second position is summed up in the famous Cartesian motto, "I think, therefore I am." In this sentence, the criterion of mind, as Descartes conceived it, which was also its specific character, was given formal statement. Mind differs from body by its consciousness of its own thinking process; and in this it finds the immediate evidence of its existence as a peculiar mode of reality. The formal mode of statement should not obscure the essential import. It is not an argument, properly speaking, for the thinker himself; it is such only to the outsider. To consciousness, to the thinker himself that is, it means, "I am here thinking," "I catch myself having thoughts," cogitans, sum. To the outside observer it means that by its thinking the mind knows itself to be different from matter, which is extended, and to be a sort of existence or reality sui generis.
The significance of both these elements of Cartesianism appears from the preceding history. They were both equally inevitable and both at the time equally mature. The final culmination of the mind-body dualism was prophesied in the first suggestion of the distinction made by Empedocles and Anaxagoras, and [p. 111] developed through all the vicissitudes of Greek and Mediæval philosophy. So plain is this that we have been justified in describing the progress of philosophy so far as the genetic history of dualism. Moreover, it is matched, in its main stages, by the similar history of the individual's thought. The individual grows to know the "self" as a principle different from body. In both alike, the issue in a hard-and-fast substantive dualism seems inevitable: there is an extended body, existing over against a conscious spirit or mind. The dogmatic spiritualism of the Church fathers receives now the authorisation of speculative thought.
The point of novelty in the Cartesian statement consists in this, that the dualism becomes an ontological one; it does not remain merely logical, religious, practical, but becomes metaphysical -- a formula of reality, the presupposition of future science and philosophy. So definite is this that the interest after Descartes consisted no longer in pointing to evidence of the disparate nature of mind and body, but of finding a method of accounting for their seeming relation and interaction. The dominant problem of the thinkers immediately following Descartes was the psycho-physical one: how could the two heterogeneous substances, mind and body, sustain any relation at all to each other?
The second position, embodied in the saying, cogito, ergo sum is also the issue of a long travail. Rising in the relative isolation of the subjective point of view by the Sophists and Socrates, the current of subjectivism gathered force in Platonism, Mysticism, and Stoicism, and finally became fully aware of itself in St. Augustine, who might have said in form, as we have before remarked, "I will, therefore I am; volens sum." [p. 112]
This current had to rid itself of the jetsam of Aristotelianism which obscured the subjective in the vital, and of the flotsam of both Platonism and Sensationalism, which equally, though in different senses, deprived it of its true meaning. But the inner point of view constantly gained in clearness, and finally defined itself in essential terms: the point of view of consciousness as essential mark of mind and starting-point or presupposition of reflection. The problem of self-consciousness as such arises.
These are the issues of Cartesianism. The substance mind differs generically from the substance body; and the specific proof of this difference is seen in the opposition between the extended thing and the thinking self. And the thinking mind knows itself and sets itself over against all the objects of its thought.
Of Descartes' more detailed and special theories, that of "animal automatism" is the most significant. He rejected altogether the conception of an animal or vegetable soul different from the rational; and held that the organism was governed by the same physical and mathematical laws as other bodies in nature. The unreasoning animals are "automata," living machines. Man alone has the power of directing his movements
For the "image" theory of sense perception, Descartes substituted a mathematical conception finding the sense-stimulus in "vibratory" rays or undulations (light, air, etc.), expressed in mathematical formulas. These produce effects in the organism which are in no sense "like" the object perceived. [p. 113]
In his doctrine of emotion, Descartes comes to the verge of a psycho-physical theory, in spite of the difficulty of conceiving any interaction between the two disparate substances. He held that the heart, actuated by heat, due to its own processes of combustion, produces "animal spirits" or fluids (spiritus animales). These circulate through the body and affect the seat of the soul (the pineal gland in the brain). This results in sensations, perceptions, and emotions. The entire life of perception and feeling has this physical basis. Memory is due to the second or subsequent passage of the animal spirits receiving the spores or residua of their earlier action.
Thinking has its clear and evident principles, innate ideas -- extension, number, duration, existence, etc. -- given to the soul much as the immediate knowledge of the self is given to it. These are in contrast with the obscure and confused perceptions of sense. In this theory, the problems of the criteria of immediate certainty -- "clearness and distinctness," according to Descartes -- and of the existence of "innate ideas" were brought into philosophy, to be bones of contention, the latter problem especially, to thinkers from Locke to Kant.
Under the term "thought," Descartes included all the operations of mind. He distinguished, however, between "passions " and "actions," passive and active operations of mind. He called them "perceptions" and "volontés." The intelligence, no less than the feelings, considered as caused by the action of objects, come under the heading of "passions."
The idea of God must be true, since no object save God could cause an idea of the infinite and perfect. [p. 114] Further, God is the guarantee of the validity of the clear and distinct ideas generally, since we cannot suppose he would deceive us. Thus the certainty of the object of knowledge rests upon the certainty of the existence of God.
In all the details, we find the tendency to clarify the conception of soul, by restricting its presence to those purer and more intellectual processes in which dependence upon physical states is not in evidence. This results in the passing over of the lower functions -- sensation, feeling, movement -- to the spatial and physical. Thus the dualism is sharpened between the one substance which thinks, and the other which is extended.
II. Occasionalism and Pre-established Harmony. -- The immediate result of the dualism of Descartes was to give further emphasis to the embarrassing psycho-physical relation. So urgent did the question of mind and body become that its answer was the burden of ail the subsequent thought of the school.
In Occasionalism, the next step was taken. Geulincx and Malebranche distinguished between a "cause " and an "occasion." A cause is a real source of action, producing an effect which without it would not have been produced. An occasion, on the contrary, is merely the more or less accidental circumstance under which the true cause acts, or by which it is interfered with or prevented from acting. For example, the pulling of the trigger of a gun is the occasion of the expulsion of the ball; the cause is the explosion of the powder.
Applying this distinction, the "occasionalists" said that the mind acted as occasion of the movements of the body, not as their true cause. Being disparate in [p. 115] character, will and body could not act causally upon each other. But the will could serve as occasion for the true cause, the action of God. Both sensation, which seems to be caused by the external object, and movement, which seems to be caused by the mind, are in reality caused by God.
This occasional relation of mind to body served the human purpose of volition, but at the same time did not impair the divine truthfulness as embodied in the two clear and distinct ideas.
This view is represented to-day, in kind, in the theories which hold that while the mind cannot alter the energy of the brain in quantity, it can direct the discharge of this energy in one nervous course rather than another.
The superficiality of such a conception prevented its being more than a stepping-stone to the radical doctrine of "pre-established harmony." One may avail oneself directly of Descartes' suggestion as to the original effective act of God, rather than distribute the divine influence through a series of special acts. It is part of the original act of causation, one may say, that all possible cases of apparent interaction of matter and mind have been provided for. Whenever such a case appears, presenting concomitant changes in both mind and body, it is due to a "harmony" arranged for, pre-arranged, "pre-established," in the creation of each. Each changes because it is so made, not because the other changes. Each mould change if, lacking such complete harmony, the other did not. It is inexorably arranged that my arm should move whenever my will exercises itself, and seems to move it, just as it is inevitable that two clocks, each regulated by the divine harmony of the spheres, should strike at the same [p. 116] instant, and seem to influence each other to do so. The two series of events, mental and physical, therefore, are quite independent of each other. There is no interaction whatever. The conditions under which Leibnitz developed this view further are noticed on another page below.
These doctrines, it is clear, did not affect psychology much beyond fixing the Cartesian points of view. Automatism is extended in theory to the human organism. The body moves independently of mind by a divine decree, which acts on occasion of a volition or which establishes once for all its harmony with volition In either case, there is thc explicit assumption of the act of God -- a metaphysical principle, a deus ex machina, serving as first cause and prime mover of mind and body alike. This leads to a new dogmatism of method and a new absolutism of result in the schools of Wolff and Spinoza, which obscured the Cartesian light of immediate self-consciousness. The gulf was thus widened between the rationalist schools of the Continent and the empirical school in England.
In Malebranche (1638-1715), however, we find the development of the doctrine of occasional causes into a general idealistic theory of knowledge. The soul, says he, cannot know things themselves: things are only the occasion of the rise of ideas in the mind. The true cause of all ideas is God, in whose presence and action the world is perceived. Even the ideas of the perfect and infinite cannot be innate to the soul, for it is finite and imperfect. These ideas -- that of God himself -- are divinely aroused in the mind on the occasion on the contemplation of the world with attention. Hence the saying of Malebranche, "We see all things in [p. 117] God." Actions, moreover, acts of will, are volitions of God, since our desire is only their occasional, not their original, cause. The active life, like the intellectual, is lived in God.
In this a-e find a return to the Platonic "idea," with a commingling of Neo-Platonic mysticism. In so far it abandons the point of view of empirical conscious process, and prepares the way for the theory of the identity of mind and body in the absolute, as announced by Spinoza. Yet in one important point Malebranche was a dualist, not an absolute idealist: he held that the knowledge of the soul through self-consciousness was more superficial than that of the body. We have a profound knowledge, in his view, of space and its properties -- the essence of matter; but we know only particular states of mind, not general and universal truths. God, therefore, is rather a postulate of logical and theological value, not a principle capable of unifying the terms of the mind-body dualism.
Malebranche showed himself, indeed, to be a first-rate psychological observer. He investigated vision with notable results; working out a vibration theory of colour differences, a theory of accommodation, an account of visual depth-perception. He was led also into the investigation of sense-illusion by the objection raised to his occasionalist view, to the effect that God often deceived us in these cases.
Spinoza. -- In Baruch de Spinoza (1632-77), one of the heroic figures of philosophy, the dualistic theory received its final philosophical statement -- final, that is, in the sense that to go beyond the Spinozistic formulation is to merge the two terms in an identity so unifying that their differences disappear altogether.
Spinoza employed a deductive and mathematical [p. 118] method. His great work, Ethica, consists of a series of propositions and demonstrations, with corollaries drawn out in the manner of geometry. In his opinion neutrality and objectivity, no less than mathematical validity, were thus given to the conclusions reached.
Admitting the truth of the distinction between mind and matter, and that of the impossibility of any interaction between them, there is, said Spinoza, one other truth equally indisputable: the changes, relations, and events taking place in them occur in strict correlation: "the order and connection of ideas is the same as the order and connection of things" -- ordo et connexio idearum idem est ordo et connexio. How is this possible -- assuming the truth of the dualism already agreed to?
It is possible, said Spinoza, in formal agreement with Malebranche and Geulincx, only because of the presence of the activity of God in both. But how is this presence to be conceived? Here the thought of Spinoza takes form in a system of absolute formal identity.
God is the only, the one, substance; but being infinite, God must have an infinity of attributes. Nothing conceivable can be denied of him. Of this infinity of attributes, we are able to know only two: thought and extension, mind and matter; but the infinity-less-two attributes must have equal reality. Mind and body, therefore, are equally independent of each other and of all the other attributes, but they are also equally dependent upon the one infinite substance, God.
Whatever takes place in one of the attributes, say a thought in the attribute mind, or a movement in the [p. 119] attribute body, must have a corresponding place in each of the other attributes, since it is a modification of the one substance, God. The mode of thought -- "mode" is Spinoza's term for any specific determination within an attribute -- must have a corresponding spatial mode; and each mode of movement, a corresponding thought mode. Thus the correlation is established. Every event in thought or extension is also an event in extension or thought.
What, then, is this one substance? Only the sum of its attributes: more we cannot say. It cannot be defined by the predicates of thought; for "all definition is negation." To affirm one predicate is to deny its opposite, and nothing can be denied of the infinite substance. To make it mind, would be to deny its attribute matter; and so on for all the unknown attributes. This is the explicit declaration of Spinoza, whose system is refractory to any interpretation in a subjective or idealistic sense.
The formal logical requirement of identity has its proof in the actual existence of the correlated modes in the attributes of thought and extension.
The emphasis is thrown back upon the attributes, upon the realistic and dualistic happenings of the life of thought in the world of extension. Even will and intelligence do not exist in God: they are modes merely in the finite attribute, mind. Spinoza's flight of speculation justifies the existing order, and makes it possible [p. 120] to pursue the sciences, physiology and psychology, without embarrassment from the problem of interaction. It is a metaphysical anticipation of the forms of truce established in the development of science -- the theory of "parallelism, " the " double-aspect theory," etc. -- which banish the problem of cause as between mental and physical phenomena, and confine attention to the facts in the two domains respectively. While, therefore, Spinoza could not join the Positivist camp -- he was one of the arch-metaphysicians in the eye of Comte -- still, we may say that in his doctrine of identity the absolute becomes so tenuous, characterless, and harmless that science may entirely ignore it. The natura naturans shows itself only in the natura naturata, as Spinoza puts it - absolute nature appears only in phenomenal nature.
Spinoza was also psychologist. He distinguished, in the traditional way, the stages of intellectual apprehension -- imagination, intellect, intuition. He found it difficult to carry out a theory of general knowledge and abstract intuition, in the face of his doctrine of concomitant modes of mind and body; since the physical mode must correspond to the object of thought and also to the modification of the self. But this difficulty loses some of its force when we realise that the physiological event accompanying a general idea or the general self need not itself be "general"; it need only be specific. One brain modification may correspond both to the thinker and to the object of his thought.
The active life was to Spinoza the development of a fundamental "will to live," a tendency (conatus) toward self-conservation. Immortality was upheld by a curious argument ad hoc, in effect this: the personal [p. 121] soul is not the highest or true soul by which thought is manifested. There is a higher and purer mode than this, and with it there is associated another mode of body. At death this latter, the truer body, accompanies the immortal soul in accordance with the principle of the concomitance of the modes.
Leibnitz (1646-I1716). -- As mathematician and philosopher, Leibnitz is classed among the greatest geniuses, by reason of the comprehensiveness of his powers. He has been called the Aristotle of modern times. His views are fundamentally metaphysical, since he starts out from the conception of substance. But in consciousness he finds the character of substance. Mind is the explaining principle of all reality. Leibnitz is at once a monist and a pluralist: a monist so far as qualitative distinctions of substance are concerned; he accepted only one substance, the soul: a pluralist so far as independent centres of existence or reality are concerned; there are many independent souls, irreducible "monads."
It is among these independent monads or soul-atoms, each conscious, that the pre-established harmony of the world shows itself. The body is an aggregate of monads, in essence souls. There is no matter as such: only the spiritual monads exist. These aggregates range from the inorganic, through plants and animals, up to man. In the aggregates higher than the inorganic there is a central monad or soul, which in appearance rules the rest; but the law of the relation is that of pre-established harmony.
The monad or spiritual atom is self-active, never passive. Its essence, as shown in consciousness, is [p. 122][figure][p. 123] activity of "presentation," taking form in will and thought. This one activity or mental energy shows itself continuously in all the development of the mind, beginning with the "dark" or unconscious presentations present even in thc inorganic world, and ending with the "clear" analytic thought of human reason. In its nature this activity is both distinguishing and relating. The elements unconsciously present in the "dark" presentations of the lower orders of monads, are brought out in the relational form of thought in the higher. And in the development of the individual mind, progress consists in this advance from unconscious complexity to conscious relation. In it all, the specific character of consciousness, and that of all reality, is "unity in variety " -- variety of elements in the unity of the one conscious activity. The highest stage involves not only clear relations of elements, but also consciousness of self as the active unity. To this Leibnitz gave the name of "apperception," in contrast to the mere "perception" of the lower stages.
The entire progression from lower and obscure to higher and clear knowledge is native to the soul; it all belongs to its original power of presentation. To the statement of the sensationalists to the effect that there is nothing in reason that was not already present in sense, Leibnitz replies, "except reason itself," nisi ipse intellectus.
The synthetic character of Leibnitz's views, thus briefly described, becomes at once apparent. He held to a monism of substance, thus making the harmony of world-activities possible: each of the monads "presents" or reflects all the others; it is a mirror of the world, a "microcosm." But he established a pluralism of individualities, differences among the particular [p. 124] centres of reality, as it had never been done before The character of the soul as a unitary energy or activity is not lost either in its qualitative sameness with other souls, or in the differentiation of presentations within its own thought. The fruitful but much overworked principle of modern speculative idealism, "identity in difference," had here its earliest and perhaps its soundest exposition. In this connection, the principle of "sameness of indiscernibles" was formulated and applied: the proposition that without real differences, only abstract identity of apprehension is possible. For perception indistinguishable things are identical.
In the theory of the one activity or energy, spiritual in character, pan-psychism is revived; but in a form that emphasises individuality. A "social" character, so to describe it, is introduced into the structure of the world. The difficulty, indeed, with Leibnitz's pluralism would seem to lie on the side of its insufficient unity. The monads lack essential and immanent bonds of union. Their systems of presentations merely duplicate one another. And the doctrine of God, the supreme monad and cause of the unity of the world, remains obscure. Leibnitz further incorporates in his system the genetic and vitalistic points of view of Aristotle, interpreting life, however, in terms of mind, rather than the reverse. In this connection, his theory of unconscious presentations, petites perceptions, which have the power of developing into conscious cognitions, is based upon sound observation. Certain of his special [p. 125] arguments, however, drawn from the composition of colours, sleep and the summation of infinitesimally small stimulations, are of very unequal value. They are all used, in varying forms, and variously criticised in later literature of the "unconscious." It was in Leibnitz, as Harms remarks, that the series of explanations of the clear by the obscure, the positive by the negative, the conscious by the unconscious began. It reached its culmination in Schopenhauer and Hartmann, and remains the resort of many pseudo-explanations -- from crime to genius; from art and invention to hysteria; from sexual manifestations to religion -- in the psychology of to-day. By making consciousness unconscious, whenever other explanations fail, of course one enlarges one's resources.
Finally, it is to be noted that the form given by Leibnitz to the postulate of self-consciousness -- making it active in its very nature-asserts a positive spiritualism as over against the passivism found in the empirical psychology of the British school.[l0] The mind is not a tabula rasa, a blank tablet, receiving impressions from outside itself; it is, on the contrary, the fons et origo of all action. The mill is the principle by which the flow of presentations in consciousness takes its determined course; it is the dynamic aspect of mind.
In short, we find in Leibnitz's psychology a synthesis of elements drawn from Aristotle, the Stoics, and St. Augustine; the whole recast in the form made possible by the development of the dualistic motives in and after Descartes. It has left an indelible mark upon [p. 126] modern thought. In view of its metaphysical point of departure, and its explanation of the world in terms of mind, we may consider it as the culmination of the rationalism of Descartes and Spinoza. With reference to later developments, we may note that it lacks the radical distinction between intellect and will which marked and differentiated the systems of subsequent idealistic thought.
Dogmntism. --- Christian Wolff (died 1754) defined the doctrines of Leibnitz, each for itself, in such a may that they lost their relation to the system as a whole. They became a series of dogmatic statements. His method, moreover, was ultra-logical, proceeding by definition and distinction. The "monad" became the "atom" again. The power of "presentation" was restricted to the mental or conscious atoms. Pre-established harmony took the form of an order established once for all by the act of God. There was no possible direct interaction between mind and matter.
The activity of the soul, described as in itself one, takes on, according to Wolff, different directions, appearing in different "faculties," of which the vis repraesentativa, or "logical faculty," is fundamental. The active faculty or will is due to the same fundamental movement. The faculty of imagination, belonging to knowledge in general, produces representations connected by the law of association in the form of statement that a partial reproduction revives the whole of which it was formerly a part.
Wolff distinguishes memory, poetic fancy, etc. -- faculties arranged in order and treated with much psychological insight. The emotions are mixtures of [p. 127] pleasure and pain, which reflect respectively the relative clearness or obscurity with which unity in variety appears in the mental life.
Although dogmatic and unoriginal in his philosophy, Wolff undoubtedly aided the progress of psychology; principally, however, by sharpening its problems. The suggestion of "faculties" soon crystallised[sic] in the extravagant "faculty psychology" which cut the mind up into water-tight compartments, each doing its peculiar work in independence of the others. The distinction made by Wolff between a "rational" or philosophical, and an "empirical" or observational, psychology was in line with a later division of problems and interests; but his books on these two sorts of psychology illustrate the difficulty of carrying out the distinction from his point of view. To him "rational psychology" was a deductive metaphysical discipline, over against the inductive and empirical science. The former should rather have been called the "psychology of rationalism." His distinction between the two is not that which modern psychology recognises in differentiating between the observational problem with which science begins, on the one hand, and the explanatory problem, on the other hand, with which she concludes. This latter distinction was developing in a sounder way in the work of the British Empiricists.
The movement traced in this chapter -- from Descartes to Wolff -- shows the development of one of the great motives of reflection: that which exhibits, in [p. 128] philosophical and reasoned form, a rational solution of the problem presented by the sharp Cartesian dualism of mind and body. In the different theories, having this motive in common, the alternatives re-occur which came forward, in less reflective form, in Greek and Mediæval thought. In succession we see bare and barren dualism in Descartes, "creationism" in Malebranche, "absolute idealism" and "identity" in Spinoza, psychic " atomism " and "pan-psychism " in Leibnitz. They all employ the postulate of rational certainty as attaching to knowledge, and follow a deductive method. They all identify the rational principle with God. It will be profitable, before going further, to make these points a little clearer.
The dualism of Descartes was more "bare and barren " than that reached at any time by the Greeks, because it was more conscious and uncompromising. The last ambiguity of matter, as well as the last embarrassment of mind, was removed; the divorce of interests was complete. The extent of the damage suffered by psychology is seen in the automaton theory by which all possible vital connections between soul and body were denied. The theory of naturalism was extended, it is true, but entirely in the sense of enlarging the sphere of the physical. The psychical, beyond being defined as "thought," was placed more than ever beyond the reach of positive method.
The solution offered by any sort of creationism, as in the Church Fathers and Malebranche, only made the issue more obscure by setting a term to investigation. To say "the world is made of nothing " simply means that God is its cause in every sense, material and formal alike. The tendency then becomes -- as it showed itself in the Greeks -- to make of "nothing" a [p. 129] sort of negative "something" upon which God could act and out of which the world could take form. The "non-being" of the Greeks became a negative something against which the positive divine impulse asserted itself. This was developed in the post-Kantian idealism on lines laid down by Böhme.
The new departures found in Spinoza and Leibnitz show an interesting contrast. The one "cuts under" the dualism of thought and extension, leaving its superficies intact, just as we put a cellar under a house! God is the unifying principle, the foundation-stone on which both pillars of this structure of reality rest. Our separation of the parts, the attributes, obscures our vision of the whole, the substance. There is but one substance.
To Leibnitz this division of reality into two substances is equally superficial; but his way of surmounting it is the very opposite to that of Spinoza. He reaches one substance, but makes it pluralistic, atomistic, in its properties. Instead of an infinite attribute we find an infinitely small soul-monad. And by cutting up the substance thought into an infinite number of bits, the substance extension is made to disappear.
For psychology the main thing was the continued importance attached to intellect, reason; this part of Cartesianism was not outgrown. Reason was the thing to account for and reason was the instrument by which to account for it.
Empiricism. -- Another great current of thought was gathering force across the Channel; moving in a direction opposed to "Rationalism," and known as "Empiricism."
In Gassendi and Hobbes the empirical tendencies of [p. 130] the Pre-Cartesians, Vives and Roger Bacon, focused themselves. As in Descartes a series of rationalistic theories took their rise, so in Gassendi and Hobbes -- who directly opposed Descartes personally -- the naturalistic and materialistic series began. The dualistic idealistic philosophy was opposed by the monistic-sensationalistic. Gassendi (1592-1655) developed the atomism of Epicurus, but admitted the possibility of a sort of soul-molecule in the primitive matter. He also made reason the function of a special immaterial soul created, as the atoms were, by God.
It was Hobbes (1588-1679) that the two fundamental positions of Cartesianism were alike assailed: the subtance view of mind and the rational theory of thc origin of knowledge. Mind, said Hobbes, is a function of body, and reason is a product of sensation. The world is made up of matter in motion under mathematical laws; and consciousness is one of the aspects or characters of the living organism. There is, then, no separate substantive soul or spirit as the dualists declare.
Further, sensation is the one conscious event, and upon it knowledge is founded. Sensation is based upon physiological processes, stirred up by external stimulation. Hobbes describes these organic processes, making the heart the centre. By the compounding of sensations -- the process so greatly developed by later sensationalists and associationists -- all the modes of intelligence are produced. With sensation goes an original form of impulse -- identified with the preservation of life -- and also feelings of pleasure and pain. These, like the sensations, are compounded under the laws of association. The whole results in a conception thoroughly naturalistic [p. 131] and mechanical in spirit, but its carrying out is inadequate and sketchy. It served as programme, however, for the later more deailed[sic] attacks upon rationalism, which carried the warfare into the special fields of innate ideas and the theory of knowledge.
The verve of Hobbes' philosophy was directed toward political theory; and in this he established the bond between sensationalism and political individualism, which remained vital and persistent during the development of eighteenth-century British thought.
 Descartes founded the branch of mathematics known as Analytic Geometry.
 It is by a resort to "universal doubt " that Descartes establishes this; the only thing to which effective doubt cannot attach is self-consciousness, since to doubt this is to question the very process of thought in which doubting itself consists. The "I am" is necessary for the "I doubt."
 "In the intellectual life of Greece ... the complete severance of spirit and nature had not yet arrived: the subject had not yet reflected upon itself. ... The turning of self-consciousness upon itself, which was the standpoint of the post-Aristolelian speculations, forms in Descartes the starting-point of a new philosophy." -- Schwegler, Hist. of Philos. in Epit., pp. 184-185.
 Descartes, Les Passions de l'âme.
 Ethica ordine geometrico demonstrata. Trans. and introduction by Sir F. Pollock, Spinoza, his Life and Philosophy, 2nd ed. 1899
 Determinatio est negatio, Epist. 50.
 This is in opposition to some commentators, as Pollock, who find a tendency in the attribute thought to "swallow up all the other attributes," based upon Spinoza's Definition 4 of Attribute ("that which intellect perceives concerning substance," cf. also Epistle 27).· A refutation of this view with citation of texts is to be found in the writer's paper, "The Idealism of Spinoza,'' Fragments in Philosophy and Science, Chap. II.
 Leibnitz worked out a systematic theory of the monads calling it "monadology."
 The correlated principle of "difference of discernibles" is equally true: one thing becomes two or many when differences of appearance prevent its identification (see the writer's Thought and Things, Vol. II, Chap. XIV, §8).
 The title of Leibnitz's New Essays on the Human Understanding (Nouveaux essais sure l'entendement humain) has reference to that of Locke's Essay concerning Human Understanding.
 This anticipates the "Law of Redintegration" formulated by Sir William Hamilton.
 An historical review of the doctrine of "faculties'' is given by Klemm, loc. cit., pp. 44-70; and in Dessoir, loc. cit., is to be found a section on the "German Faculty Psychology" following Wolff."
 Empirische Psychologie and Rationelle Psychologie.
 This showed itself in the union of philosophy and "civil polity" in the chairs of instruction in the universities. In T. H. Green at Oxford, and H. Sidgwick at Cambridge, in the last quarter of the nineteenth century, the two interests still showed themselves closely united.