Condillac, like Locke, started with the proposition that all our knowledge comes from experience. While, however, Locke had indicated two sources for this knowledge, sensation and reflection, the outer and the inner sense, Condillac referred reflection to sensation, and reduced the two sources to one. Reflection is, with him, only sensation; all intellectual occurrences, even the combination of ideas and volition, are to be regarded only as modified sensations. It is the chief problem and content of Condillac’s philosophizing to carry out this thought, and derive the different functions of the soul out of the sensations of the outer sense. He illustrates this thought by a statue, which has been made with a perfect internal organization like a man, but which possesses no ideas, and in which only gradually one sense after another awakens and fills the soul with impressions. In such a view man stands on the same footing as the brute, for all his knowledge and all his incentives to action he receives from sensation. Condillac consequently names men perfect animals, and brutes imperfect men. Still he revolts from affirming the materiality of the soul, and denying the existence of God. These ultimate consequences of sensualism were first drawn by others after him, as would naturally enough follow. As sensualism affirmed that truth or being could only be perceived through the sense, so we have only to reverse this proposition, and have the thesis of materialism, viz.: the sensible alone is, there is no other being but material being.
_Helvetius_ has exhibited the moral consequences of the sensualistic standpoint. While theoretical sensualism affirms that all our knowledge is determined by sensation, practical sensualism adds to this the analogous proposition that all our volition springs from the same source, and is regulated by the sensuous desire. Helvetius adopted it as the principle of morals to satisfy this sensuous desire.
Helvetius was born at Paris in 1715. Gaining a position in his twenty-third year as farmer-general, he found himself early in the possession of a rich income, but after a few years he found this office so vexatious that he abandoned it. The study of Locke decided his philosophic direction. Helvetius wrote his famed work, _de l’Esprit_, after he had given up his office and withdrawn himself in seclusion. It appeared in 1758, and attracted a great attention at home and abroad, though it drew upon him a violent persecution, especially from the clergy. It was fortunate for him that the persecution satisfied itself with suppressing his book. The repose in which he spent his later years was interrupted only by two journeys which he made to Germany and England. He died in 1771. His personal character was wholly estimable, full of kindness and generosity. Especially in his place as farmer-general he showed himself benevolent towards the poor, and resolute against the encroachments of his subalterns. The style of his writings is easy and elegant.