ETIENNE BONNOT DE CONDILLAC (1715-1780), Abbé de Mureaux, a distinguished writer in logic, psychology, and economic science, was born at Grenoble. Very little is known about the particulars of his life. He was the younger brother of the Abbé de Mably, and associated in his youth with Rousseau, Diderot, Duclos, and other philosophers, but afterwards allowed the intimacy to die out. He was of a serious and dignified character, and devoted himself to a life of laborious study. Like Comte and Mill, he acknowledges himself to have been largely indebted to a lady for his philosophical inspiration, While still young he was appointed preceptor to the duke of Parma, grandson of Louis XV., for whose instruction a large number of his works were composed. He was chosen by the French Academy of Sciences to succeed the Abbé d'Olivet in 1768, but after delivering a discourse on that occasion he never again appeared at the meetings. He lived in retirement on his estate of Flux, near Beaugency, till his death on 3d August 1780.

Condillac's philosophical opinions are contained mainly in L'Origine des Connaissances Humaines, Traité des Systèmes, Traité des Sensations, Grammaire, L'Art d'Écrire, L' Art de Raisonner, L'Art de Penser, La Logique, and his posthumous work, La Langue des Calculs. The first of these was his earliest production, and may be regarded as the preliminary sketch of his entire system. It touches more or less distinctly on all the topics which are discussed in the others. But the doctrines it contains receive a fuller and more mature statement elsewhere, and there are many important departures from them in the later works.

Condillac's philosophical writings may be studied from three points of view. Like Locke, he begins with a polemic against innate ideas and abstract systems. This takes up a large part of the Essai sur l'Origine and almost the whole of the Traité des Systèmes. In the Logique and the Art de Raisonner he expounds and illustrates the analytic method, which he regards as the only true method of science, and which is further illustrated in La Langue des Calculs. L'Art de Penser consists largely of quotations from the Essai sur l'Origine. In the Traité des Sensations, Condillac applies his analytic method to the solution of the psychological problem of the origin of our ideas and the formation of the mental faculties. It cannot be said that he strictly confines himself to the questions here assigned to his different works. His inveterate antipathy to innate ideas and abstract systems, his favour for analysis, and his peculiar psychological doctrines appear more or less in them all.

Condillac's main attacks are directed against the innate ideas of Descartes, Malebranche's theory of the mental faculties, the monadology of Leibnitz, and the first part of Spinoza's Ethik. He thinks that innate ideas were assumed because men had not sagacity and penetration enough to go back to the origin of ideas and trace their genesis, and he finds the consequences of the system to be the multiplication of abstract principles, and a pretence of accounting for everything by the use of abstract terms. Malebranche is justly censured for giving comparisons instead of reasons in his explanation of understanding and will. In criticizing the monadology of Leibnitz, Con-dillac exaggerates the vagueness and inadequacy of the ideas furnished by the reason, and the clearness of those of the senses. He cannot comprehend how each monad represents the universe in virtue of its relations to it. But may there not be a sense in which the ultimate particular in the infinitude of its relations is a mirror of the universe 1 Condillac regarded Spinozism as the best example of an abstract system, and criticized in detail the first part of the Ethik, in order to show that Spinoza failed both as to clearness of ideas and precision in the use of signs—two essential conditions of the geometrical method which he adopted. Condillac divides the various philoso-phical systems into three classes:—(1) abstract systems which rest only on abstract principles ; (2) hypotheses, or systems grounded on mere suppositions; (3)one true system, that of Locke, which is evolved from the facts of experience. The first he treats with unmitigated scorn ; the second he admits under limitations ; the third alone he regards as the true method of philosophy.

An act of reasoning, according to Condillac, consists in detecting a judgment which is implicitly contained in another. Sometimes, to go from the known to the unknown, it is necessary to pass through a series of inter-mediate judgments, each of which is contained in the one preceding. For example, the judgment that mercury will rise to a certain height in the barometer is contained implicitly in the judgment that air has weight; but we require a series of intermediate judgments to see that the former is a con-sequence of the latter. The evidential force of a reasoning thus consists in the identity between the judgments of which it consists. They are the same ; only the expression changes. Such a principle could not be made to cover all the varieties of reasoning. Accordingly Condillac tries to reduce them all to the mathematical form. To reason is to calculate, and to calculate is to reason ; and reasoning, like calculation, comes to be a merely mechanical operation. Condillac rejects the common explanation of reasoning, that it is a comparison of two terms with a common third to find their relation to each other. He sees no need for a middle term. The force of the demonstration, he thinks, lies in the identity of the two extremes, which is made evident by decomposing them. Of the syllogism he says that it makes reasoning consist in the form of expression rather than in the development of the ideas, and that most of its rules have been framed with a view to concluding from the genus to the species, whereas thought sets out from particulars.

Regarding the criterion of truth, he attacks the Cartesian test of truth, and proposes instead of it his own criterion of identity. In the Essai sur VOrigine des Connaissances he brings two objections against Descartes:—(1) the methodic doubt is insufficient and even useless, because, while calling our ideas in question, it leaves them in all their indeterminateness; (2) it is impracticable, for we cannot doubt about the relations which exist between familiar and determinate ideas like those of numbers. Of the Cartesian criterion of truth, " all that is contained in the clear and distinct idea of a thing may be affirmed of it with truth," Condillac says that it is both useless and dangerous, and should not have been extended to cases different from the one which gave it birth. For Condillac the sign of truth is identity. The evidence of a proposition is in the identity of the two terms. The evidence of a reasoning is in the identity of the successive propositions. No definition, however, is given of identity. It is said to be recognized when a proposition can be expressed in terms equivalent to these,—" the same is the same." But Condillac draws a distinction between identical proposi-tions that are frivolous and those which are instructive, and explains the latter to be those in which the terms are identical in thought, but different in expression. Condillac held that three kinds of evidence are needed to arrive at certainty—the evidence of fact, the evidence of feeling, and the evidence of reason. The evidence of fact informs us of the relations which bodies have to us ; it can have no other object. The evidence of feeling enables us to distin-guish what passes in us, the modes or states of the mind. Some good remarks are made in chapter iii., part i., of L'Art de Penser, on the attentive observation of conscious-ness. The evidence of reason is discussed in the first three chapters of the first part of L' Art de Raisonner. There Condillac merely formulates the principle of identity, and cites as examples the geometrical theorems which his pupil will require, that he may understand the rest of the work.

Condillac was of opinion that one method of analysis is common to all the sciences. Our cognitions ought to form a system in which all is strictly connected together. Every series of facts should be reduced to an initial fact, of which the others are only transformations. Identity is a rule of method as well as a criterion of certainty; and analogy completes the primary lessons which are given us by nature. Condillac takes as his model the method of mathematics, and reiterates through his logical writings that we must take nature for our guide. On the relation of analysis to language he held that there is an innate language, although there are no innate ideas. This language produces a kind of analysis, since it is necessary for the communication of our ideas to analyze and express in succession what is simultaneous in thought. Analysis then reacts on language and improves it. Finally, perfec-tion of language leads to perfection of analysis, and science is only a langue bien faite.
The method of invention is discussed chiefly in the Essai sur I' Origine des Connaissances and in the Langue des Calculs. In the former, Condillac bids us take the simple ideas furnished by sensation and reflection, form different collections of them, which in their turn will produce others, and give distinct names to these different collections. In the Langue des Calculs the idea of analogy is developed. This is not the analogy set forth in the Art de Raisonner, which consists only in forming more or less probable conjectures about the unknown from the known. The analogy of the Logique and the Langue des Calculs is that which creates and regulates languages, which causes us to invent different systems of signs and submit them to uniform rules.

Reasoning cannot have the purely subjective character which Condillac's theory assigns to it. It takes its-departure from the idea, which is objective, and therefore establishes a real relation between the mind and its object. On the question of the need for a middle term it is not enough to decompose the two ideas. The two decomposi-tions must meet at a point, and that is the middle term. Laromiguiere preserves the intermediate ideas, which he thinks are found by analysis of the extremes. So they are. But it has been urged that there is a twofold analysis—of the species into its genera and of the genus into its species _—whereby the middle term is found. Condillac is incon-sistent with himself in his criticism of Descartes. His first objection to the methodic doubt is based on the opinion that all our errors proceed from the indeterminate character of language, and that the use of definite signs is the only security against error. But he believes that analysis makes language; and the methodic doubt is a kind of analysis, for it remounts to the primary truths. His second objection, that we cannot doubt about mathematical rela-tions, is invalidated by his own statement that mathe-matics are only part of metaphysics. Condillac is right in saying that the Cartesian criterion of truth lacks a theory of ideas and of their origin. But it is not to be condemned as useless because it is incomplete. Condillac was led away by the supposed need for a sign whereby to recognize truth. As Hegel would have put it, he refused to go into the water until he could swim. But it would be as difficult to determine the value of the sign as that of the truth itself. Some such criterion as identity is the only resource of empiricism. But if the notion of identity is derived from experience, it cannot give certainty. If, that it may serve as the basis of logic, it is regarded as necessary, then empiricism cannot reconcile it with its psychology. Laromiguiere tries to get over the difficulty of accounting for progress in a system based on the notion of identity, by drawing a distinction between partial identity and total identity, and saying that the former alone should be admitted. But what is partial identity 1 Condillac himself takes refuge in extreme idealism. Truth, he says, considered in itself and in the divine intelligence, is one and identical. But he had himself laid down the rule to limit our consideration to the condition of human knowledge, and of course he had no idea of developing thought as such from its primal unit by a dialectic process after the manner of Hegel. As to the three kinds of evidence, Condillac in reality reduces the evidence of fact to that of feeling and that of reason. His numerous contradictions are largely due to his attempts to defend the authority of the senses, while he accepts the idealistic theory of external perception. The objections to identity as a criterion of truth apply as well to Condillac's statement of the evidence of reason. And if the three kinds of evidence are inadequate taken separately, they cannot suffice when combined. Condillac rightly insisted that there is one fundamental method for all the sciences ; but he nowhere reconciles this unity of method with the variety of form which it assumes as applied to different objects. By demanding at the outset the initial fact, of which all the others are to be shown to be transformations, he virtually quits the safe road of experience. He errs, too, in thinking that the method of mathematics is applicable to all the sciences. His oft-repeated advice to follow nature would have been advantageously accompanied by a clearer explana-tion of what nature is. One thing which he certainly excludes from it is the mind viewed as the seat of intel-lectual principles. Condillac's analysis combines what are generally regarded as the two distinct processes of analysis and synthesis. Synthesis he conceives to be that method which starts from abstract principles, and accordingly he treats it with supreme disdain. But while banishing the name he retains the thing, and insists that no analysis is complete without a process of recomposition.

The logic of Condillac finds its most important applica-tion ;in psychology. In the Essai sur l'Origine des Connaissances he starts from sensation as the primitive fact, and seeks to show that all the ideas and operations of the mind are only transformations of it. He neglected, how-ever, to make sure of his way back to the primitive fact of sensation, before using it as his starting point. Under the influence of Locke, he simply assumed it, and applied his ingenuity to derive from it all the ideas and operations of the mind. Throughout the Essai sur l'Origine he con-founds sensation with perception in a way that vitiates his whole argument. At the outset he affirms that sensations are ideas, because representative of objects. It is difficult to understand in what sense he uses such language. For a long time it was supposed that he regarded the pure sensation as the primary element of consciousness; but his more recent followers have adopted a different interpreta-tion. They try to make out that his meaning was that in the simplest state of consciousness the whole mind is to be found, equipped with all its so-called faculties. Condillac found an opinion prevailing that the mind is partitioned off, as it were, into a variety of different faculties, each having its separate function, which it discharges independ-ently of the others. It was against this opinion, they say, that he contended. He maintained that the mind is not a congeries of faculties, but is one and indivisible, and appears in all its forms of activity in the simplest state of consciousness. This opinion is difficult to reconcile with his avowed purpose, to which he adheres throughout all his psychological treatises, of tracing the genesis of the faculties; for sensation would then not be a primitive fact, from which all the later furniture of the mind is derived by a process of transformation. There would, in fact, be no generation of the faculties, for all would be given in the rudimentary consciousness, and any reasoned account of their relations to each other would need to refer to something anterior to the individual consciousness. Probably the more correct view to take of Condillac's psychology is that when he tried to deal with sensation, pure and simple, he found it impossible to do so, and was compelled to invest the mere sensation with all the ideas of reason, that it might do duty in his system. -No doubt either interpretation would save Condillac's consistency with his great principle of identity. The sameness of the elementary sensation with the higher faculties and ideas is secured, whether the faculty is degraded to the level of the sensation, or the sensation is raised to the level of the faculty. And there is much in Condillac to countenance either view. But it is probable that if he had been willing to concede that the mind is all in the primary sensation, in the sense in which his later followers understand him, he would have felt the necessity of exhibiting the relations of the different mental operations, which in such case would be moments of the sensation, anterior to the sensation, instead of subsequent to it, in terms of the relations of different sensations to each other. The opening sentences of the Traite des Sensations show that Condillac was aware of the difficulties attending the study of our rudimentary consciousness on the presuppositions of sensationalism. If the mind at birth was a tabula rasa, there can be no traces left of our primary state. It is in vain therefore to interrogate our consciousness to learn what it was then. To show how all proceeds from sensation, we must considet our senses separately. As Condillac could not do this by examining his own consciousness, he devised the experiment of the statue. It is supposed to be possessed of a mind destitute at first of every sort of ideas, and only to have the use of its senses at the pleasure of the experimenter, who opens them at his choice to their appropriate impres-sions. A beginning is made with the sense of smell, because it seems to contribute least to our knowledge. The other senses are successively experimented on, singly and in groups, and at last the statue is found to have become an animal able to preserve itself. Condillac claims to have stripped man for the first time of all his habits. Feeling is observed at its birth, and proof is given of how we acquire the use of our faculties. The principle of their development is found in the various degrees of pleasure and pain attaching to our sensations ; for none of them are indifferent absolutely. The contrast between pleasure and pain impels us to court some sensations and flee others. A sense of need is produced by the want of an object judged necessary for happiness. Needs beget desires ; old needs repeated and new ones formed are the ground of the development of our knowledge and our faculties. The outcome of Condillac's psychology is given in briefest form in chapters vii. and viii. of the Logique. Laromiguiere corrected Condillac by substituting attention for sensation as the principle of the active half of the mental phenomena. Cousin pointed out that attention is a voluntary act. He showed the essential difference between desire and will, as also between sensation and desire, and remarked that the organic impression must not be con-founded with the sensation. If the sensation is the con-dition of the exercise of the faculties, still it is not the principle of any.

Condillac defines personality to be a collection of sensations plus the ability to say "me." But this plus is of vast importance. How comes it that this particular collection of sensations can say " me 1" Because, answers Condillac, it is a collection of present and remembered sensations. But whether does the statue say " me " because it can remember its sensations, or remem-ber its sensations because it can say " me "] Is not all that is involved in saying me already involved in memory, so that his answer merely repeats the fact which it professes to explain i Condillac thought so in his first stage, as he then found the feeling of one's own existence to be an essential element of reminiscence. Then, indeed, reminiscence was distinguished by him from memory, but only in an artificial v. ay. A collection of sensations is a less correct account of personality than the synthetic unity of Kant. What renders the collection possible? For Condillac its essential condition, a unifying principle, is wanting. That cannot be found in sensation. It is a condition of the ordering of sensations, and is the all-important unit out of which a true philosophy of spirit must grow. Sensations cannot give an answer to the question what constitutes experience. Even Mill had to confess that it must at least be sensations which have the strange property of turning back upon themselves. Con-dillac has the very same phrase, " As long as the statue changes not, it exists without any return upon itself."

Thus, in their own inarticulate way, the sensationalists are compelled to postulate the synthetic unity of Kant. And just as it is present in the first fibre of personality, the first flash of self-consciousness, its various modes of opera-tion are no less essentially present throughout all the subsequent fabric of experience, and in the full sunlight of conscious life. To trace and treat them is the work of philosophy proper, which may be briefly distinguished from the natural sciences as that which deals with the universal aspect of thought, while they deal with the particular. Both are necessary factors of concrete thought. Experience will never spring out of categories alone, nor will it arise out of particulars alone. The method of observation proper to the natural sciences may lead us to the border ground of the two territories, but for exploring the region of the universals there is needed a keener vision and a deeper principle. It is the fault of Condillac, as of all the sensationalists, that he does not apply the analytic method faithfully enough to bring himself consciously face to face with the universal factor of experience. It is interesting to note in him the progress towards a more thorough use of analysis. In the Essai sur l'Origine he was of opinion that any single sensation was an idea, i.e., representative of external entities, and that a single sense is adequate to produce an experience more limited in degree, but the same in kind as ours. So he maintained against Locke and Berkeley that we can know through sight alone the magnitudes, distances, and situations of objects. His position then much resembled that of the so-called common-sense philosophers. To him an external world was as necessarily present in sense as to them; and his criticism of Spinoza, that the assumption in his definitions of what he meant to prove by means of them made his work easy, may very aptly be applied to the Essai sur l'Origine. If a complete experience is given in a single sensation, it will be easy to find it in a succession of them. But the Traité des Sensations marks an advance upon these views. Now a sensation is not per se an idea. A stricter use of analysis detects other elements in ideas. Condillac saw from the first that a sensation to be an idea must be representative of something out of the present consciousness. Now he sees that, to be so, it must either exist in the memory or be modified by judgments. That is to say, it must be the sensation of a series of sensations, which has the marvellous power of returning upon itself ; or, in more intelligible language, it must be held in the grasp of the synthetic unity of thought. In the Origine Condillac really develops experience out of perceptions, or sensations regarded as synonymous with ideas. In the Traité des Sensations he has come to know that a sensation as such is not an idea. But although he still professes to develop all the mental operations out of sensation, he is as far as ever from bridging over the gap between sensations and ideas, or even from acknowledging in his actual procedure the existence of such a gap at all.

When Condillac, largely owing, as he tells us to the influence of Mile. Ferrand, abandoned the position of the Essai sur l'Origine, that by sight alone we can judge of the magnitudes, distances, etc, of objects he seems to have been in unstable equilibrium between sensationalism and a very different mode of philosophizing. In the Traité des Sensations he shows how these judgments are founded not upon the direct intimations of sight, but upon an association that has sprung up between the sensations which we owe to different senses. The mind, he sees clearly, has come to deal with relations among sensations. He even goes the length of saying that the idea of impenetrability cannot be a sensation, but is a judgment founded on sensation. He was then on the verge of intellect proper, and within sight of something deeper than sensation. The intelligible order of things is dimly seen by him to be the reality for us, and he tries hard, in the Traite des Sensations, to show how we become aware of it through the interaction of the different senses. But just then he falls back again into sensationalism. He loses hold of judgment as the all-important element, and conceives the senses in some strange way to acquire a habit of immediately informing us of what a moment before he saw it needed an act of judgment to reach. For an instant he had a glimpse of thought as constitutive of experience. But forthwith the vision passes, and its place is taken by a mysterious and totally unintelligible habit or instinct of sense. Accordingly, in the Art de Penser, he is back again to the gross statements of the Origine, that we may find in sensation the ideas of extension and figure, and perceive as distinctly and clearly that they do not belong to us, or to what in us is the subject of thought, but to something outside of us.

It is not difficult to see how his theory of reason sprang out of his theory of the origin of knowledge, for of course his psychology was thought out before hi3 logic. If all is sensation, and we can never get beyond sensation, then our advancing knowledge must be only a ringing of the changes upon the primary sensation. The latest results will be identical in the fullest sense with the first begin-nings, and all science will be reduced GO a development of language, a series of identical expressions, to which we are driven by the limitation of our faculties preventing us from seeing the identity between remote terms. Thus, in L'Art de Raisonner, he shows at length that the demonstration of the rule for finding the area of a triangle is necessitated by our inability to see the identity between the idea we have of " measure " and that we have of the product of the height of the triangle by half the base. Similarly, the argument in the Traite des Sensations is necessitated by our inability to see the essential identity between sensation and thought. Every successive proposition is identical in idea with the preceding one, and differs from it only in expres-sion. There is no advance or development in matter. In his psychology it is the same sensation throughout. In his theory of reasoning it is always the same idea throughout. The difference is merely in form, and it is not difficult to see how, in a philosophy which neglects intelligible relations, and ignores the truth that they are constitutive of experience, form must of necessity be degraded and become mere form of words. This is the complaint which is urged by Hegel against all the natural sciences. He, so to speak, accepts the verdict of Condillac upon them. So far as they attempt to prove anything, he says, they are a mere string of identical propositions. But to Hegel form was everything. The development of the notion is what constitutes the universe ; and accordingly he thought that a different formula of reasoning must be found from any hitherto recognized. Syllogistic reasoning is not adequate to any real development of form. It sinks down into a mere change of verbal expression, as Condillac had asserted, while the matter of thought is left precisely where it was. But matter is only the potentiality of form, and form is no mere transformation of verbal expression, but an organic growth of thought. Is there any standing ground between the identity of Condillac and the dialectic of Hegel.

There are many later systems which it would be interest-ing to compare with the thoughts of Condillac, notably the psychology of Beneke, the later views of Mr Lewes, and the logical doctrines of Professor Jevons. There is a remarkable similarity between the identity of Condillac and the substitution of similars of Professor Jevons. The logical machine is almost like a realized ideal of Condillac; and Professor Jevons's new system of symbols would probably have been hailed by Condillac as the langue lien faite, the counterpart of algebra, for which he sighed in vain.

Condillac's important work Le Commerce et le Gouverne-ment was published in 1776, the same year in which the Wealth of Nations appeared. The best European econo-mists are said to be now gravitating to the opinion that Condillac's is the true conception of economic science. His work treats economic science as the science of commerce or exchanges. It was originally intended to consist of three parts, but the last never appeared. In the first part he develops the principles of economic science, and treats of the phenomena of commerce or exchanges. The second part considers the relations of commerce and government, and their reciprocal influence. The third part was to have contained a number of examples, to show that his theories had facts to rest upon as well as argument. His great merit was to have fixed upon the wants and desires of the human mind as the source of value. Hence he did not look on labour as a cause of value. In an exchange both parties are gainers, for each gives what is comparatively superfluous to him for what is necessary. Therein, he thinks, lies the spring of all commercial activity. He is a strong free trader, and answers by anticipation Saint Simon, Fourier, and their followers regarding the right of inheritance.

Condillac was a most voluminous writer. A collected edition of his works was published in 23 volumes at Paris in 1798, and was followed by another in 32 volumes in 1803. Several partial editions, contain-ing those of his works which form the Cours d'Études for the young duke of Parma, were published at different times. The following is a list of his works :—Essai sur l'origine des connaissances humaines (1746); Traité des systèmes (1749); Traité des sensa-tions (1754); Cours d'études, published in 13 volumes in 1755, comprising the "Grammaire," "l'Art d'écrire," "l'Art de raison-ner, ' "l'Art de penser," "l'Histoire ancienne" and "l'Histoire moderne," "l'Étude de l'histoire," and "Traité des animaux;" a sequel to the Traité des sensations (lî"i'5); Ze commerce et le gouverne-ment (1776). La Logique, written as an elementary treatise at the request of the Polish council of public instruction, appeared in 1780, a few months before the author's death. La langue des calculs was not published till 1798. An English translation of the Essai sur l'origine by Thomas Nugent was published in 1756, avowedly as a supplement to Locke's Essay on the Human Under-standing.

References—Louis Robert, Les Théories logiques de Condillac (Paris, 1869); F, Réthori, Condillac ou l'Empirisme et le Rationalisme (Paris, 1864) ; Laromiguière, Leçons de Philosophie, Paradoxes de Condillac; George H. Lewes, History of Philosophy, vol. ii. (1871); Whewell's I'hilosophy of Discovery (1860) ; Mill's Logic, book ii. chap. 2, sec. 2. There is an excellent account of Condillac's economic doctrines in Macleod's Dictionary of Political Economy. See also Dugald Stewart's " Preliminary Dissertation " in the eighth edition of the Encyclopaedia Britannica, vol. i. p. 172. (D. B.)