Étienne Bonnot de Condillac (30 September 1714 – 2 August or 3 August 1780) was a French philosopher, epistemologist, and Catholic priest, who studied in such areas as psychology and the philosophy of the mind. [...]

Condillac is important both as a psychologist and as having established systematically in France the principles of John Locke. Voltaire had made the English philosopher fashionable. Condillac developed his concept of empirical sensationism, and demonstrated "lucidity, brevity, moderation, and an earnest striving after logical method."

His first book, the Essai sur l'origine des connaissances humaines, keeps close to his English master. He accepts with some reluctance Locke's deduction of our knowledge from two sources, sensation and reflection. He uses as his main principle of explanation the association of ideas.

His next book, the Traité des systèmes, is a vigorous criticism of those modern systems which are based upon abstract principles or upon unsound hypotheses. His polemic, which is inspired throughout by Locke, is directed against the innate ideas of the Cartesians, Malebranche's faculty-psychology, Leibniz's monadism and pre-established harmony, and, above all, against the conception of substance set forth in the first part of the Ethics of Baruch Spinoza.

By far the most important of his works is the Traité des sensations, in which Condillac treats psychology in his own characteristic way. He questioned Locke's doctrine that the senses give us intuitive knowledge of objects, that the eye, for example, naturally judges shapes, sizes, positions, and distances. He believed it was necessary to study the senses separately, to distinguish precisely what ideas are owed to each sense, to observe how the senses are trained, and how one sense aids another. He believed that the conclusion has to be that all human faculty and knowledge are transformed sensation only, to the exclusion of any other principle, such as reflection.

The author imagines a statue organized inwardly like a man, animated by a soul which has never received an idea, into which no sense-impression has ever penetrated. He unlocks its senses one by one, beginning with smell, as the sense that contributes least to human knowledge. At its first experience of smell, the consciousness of the statue is entirely occupied by it; and this occupancy of consciousness is attention. The statue's smell-experience will produce pleasure or pain; and pleasure and pain will thenceforward be the master-principle which, determining all the operations of its mind, will raise it by degrees to all the knowledge of which it is capable. The next stage is memory, which is the lingering impression of the smell experience upon the attention: "memory is nothing more than a mode of feeling." From memory springs comparison: the statue experiences the smell, say, of a rose, while remembering that of a carnation; and "comparison is nothing more than giving one's attention to two things simultaneously." And "as soon as the statue has comparison it has judgment." Comparisons and judgments become habitual, are stored in the mind and formed into series, and thus arises the powerful principle of the association of ideas. From comparison of past and present experiences in respect of their pleasure-giving quality arises desire; it is desire that determines the operation of our faculties, stimulates the memory and imagination, and gives rise to the passions. The passions, also, are nothing but sensation transformed.

These indications will suffice to show the general course of the argument in the first section of the Traité des sensations. He thoroughly developed this idea through the subsequent chapters: "Of the Ideas of a Man limited to the Sense of Smell," "Of a Man limited to the Sense of Hearing," "Of Smell and Hearing combined," "Of Taste by itself, and of Taste combined with Smell and Hearing," "Of a Man limited to the Sense of Sight."

In the second section of the treatise, Condillac invests his statue with the sense of touch, which first informs it of the existence of external objects. In a very careful and elaborate analysis, he distinguishes the various elements in our tactile experiences-the touching of one's own body, the touching of objects other than one's own body, the experience of movement, the exploration of surfaces by the hands: he traces the growth of the statue's perceptions of extension, distance and shape. The third section deals with the combination of touch with the other senses. The fourth section deals with the desires, activities and ideas of an isolated man who enjoys possession of all the senses; and ends with observations on a "wild boy" who was found living among bears in the forests of Lithuania.

The conclusion of the whole work is that in the natural order of things, everything has its source in sensation, and yet that this source is not equally abundant in all men; men differ greatly in the degree of vividness with which they feel. Finally, he says that man is nothing but what he has acquired; all innate faculties and ideas are to be swept away. Modern theories of evolution and heredity have differed from this.

Condillac's work on politics and history, in his Cours d'études, is considered of less interest. In logic, on which he wrote extensively, he is far less successful than in psychology. He enlarges with much iteration on the supremacy of the analytic method; argues that reasoning consists in the substitution of one proposition for another which is identical with it; and lays it down that science is the same thing as a well-constructed language, a proposition which in his Langue des calculs, he tries to prove by the example of arithmetic. His logic is limited by his study of sensations and lack of knowledge of science other than mathematics. He rejects the medieval apparatus of the syllogism; but is precluded by his standpoint from understanding the active, spiritual character of thought; nor had he that interest in natural science and appreciation of inductive reasoning which form the chief merit of JS Mill. Some might claim that Condillac's anti-spiritual psychology, with its explanation of personality as an aggregate of sensations, leads straight to atheism and determinism. However, he denies both these consequences. What he says upon religion is always in harmony with his profession; and he vindicated the freedom of the will in a dissertation that has very little in common with the Traité des sensations to which it is appended. The common reproach of materialism should certainly not be made against him. He always asserts the substantive reality of the soul; and in the opening words of his Essai, "Whether we rise to heaven, or descend to the abyss, we never get outside ourselves—it is always our own thoughts that we perceive," we have the subjectivist principle that forms the starting-point of Berkeley.