Appendix 24.

(685) [Locke and the philosophy of sensation]

A small, almost imperceptible error in the pri1nciples of a system will without doubt develop in the course of time. All errors, even contradictory errors, will emerge from this one seed and spread so widely that the system itself which produced them will be held in horror. In the light of the results, the tiny, fatal seed will be removed, the system healed, and philosophy perfected. This observation is confirmed by the history of Locke's system. Locke's tiny error lay in the unsustainable vagueness of his reflection which did not provide a firm foundation for the existence of reflection.

This error was sufficient to eliminate such a vague faculty, and force a return to sensation (a more positive faculty) as the origin of cognitions. This change seemed nothing, and even appeared necessary to Locke's system. The result, however, was total upheaval and a new system. Locke, while admitting reflection in some way, was moving from internal evidence; but with reflection removed and sensation alone retained, philosophy began solely from what is external, and finished there. Condillac, in reducing philosophy to sensation, was unaware of what he was doing. He believed himself to be Locke's interpreter, but all unawares changed the entire character and nature of Locke's system.

In our time, when we can view the teaching of these two authors at a distance and feel the improvement compared with the myopia of thirty and forty years ago, we can see the difference between them. In the French Globe of 3 January 1829, we read:

It is sufficient to read the first pages of the Traité des sensations and compare them with the beginning of the second book of An Essay concerning Human Understanding, to be convinced of Condillac's extraordinary illusion in believing himself a disciple of Locke. Although the same formulas are frequently found in both works, the two men did not understand each other, despite Locke's good sense and Condillac's love of clarity; their points of view are totally different. On the one hand, Locke, shut up within himself, allows the images of the external world to come to him. On the other, Condillac places himself outside, next to his statue, and forms a soul for it out of the sensations which he grants successively to it. What is certain for Locke is myself, which he does not question and about which he allows no discussion. What is irrefutable for Condillac, and raises no problem whatsoever for him, is the external world. Locke is concerned with knowing how myself knows the external world; Condillac is concerned with discovering how the external world, acting on our senses, develops what he calls the phenomena of intellect and will in the statue's feeling. Locke solves his problem by declaring that we know the external world only through the ideas of the world transmitted to us by the senses. Condillac solves his difficulty by protesting that everything in the statue is solely a transformation of sensation. Locke is always inside, Condillac outside, just as they were at the start of their journey. For Locke there is no going out to see bodies; these must be found solely in the internal fact of ideas. For Condillac, there is no entrance which allows knowledge of the phenomena of the soul, which must be deduced from the external fact of sensation.

Condillac simply perfected Locke's error, and having perfected it, turned Locke's teaching upside down. Locke's teaching was a clear invitation to thought to reduce all ideas to sensation. We can see this from its development in both England and France, although the work was carried out independently in both countries. The philosophy of sensation did in fact appear in England at the same time and in the same way as in France.

What were the results of the philosophy of sensation?

As I said, it developed independently in England and France. This is confirmed by the fact that each country, after coming more or less to the same result (the philosophy of sensation), then began to go its own way and draw away by a different path. In France the theory of sensation developed into the materialism of Cabanis and Tracy; in England, it developed into the idealism of Berkeley and Hume.

How could such contradictory systems arise from the same principle? As I have said, the answer is: an error of itself propagates even more contradictory errors.
On the one hand, if human beings are reduced to pure corporeal feeling, and the body is necessary for feeling, each human being is a corporeal faculty. At this point it is easy to believe that the body is the sole cause of the faculty which perishes with the body. This is pure materialism.

On the other hand, if sensation is found solely in a sentient subject, and if only pure sensations exist, there is nothing outside the sentient subject. This is idealism. Hence, Pasquale Galluppi was able to show the link between Condillac's system and transcendental idealism. By making Kant begin from the foundations laid by the French philosopher, Galluppi discovered Kant's hidden path which clearly led him to his own strange system (cf. Galluppi's Lettere filosofiche, letter 4, Messina, 1827).