principle that a proposition which is inherently self-contradictory cannot be true. Truth implies a perfect agreement between our ideas {representations of things) and our impressions (presentations of things). Every inference and every postulate assumes the truth of the criterion contained in the principle of contradiction. This criterion cannot therefore be derived from mere experience: it is a priori. Every individual must possess the innate faculty of comparing impressions and drawing inferences from impressions, but this faculty cannot be derived from the impressions alone. But the a priori appertains to the individual alone. If we inquire into the origin of this faculty we must appeal to the race from which the individual has sprung. Empiricism is in error only in so far as the particular individual is concerned, not as respects the whole race. The experiences acquired by the race during the course of countless generations, the incessantly recurring influence to which it was subjected, evolve dispositions which form the basis upon which single individuals begin their course of development. That is to say, the single individual possesses in his native organization the clear profit of the experiences of untold generations. That which is a priori in the case of the individual is racially a posteriori.
Even in first edition of his psychology (1855) Spencer, who had early become an evolutionist, referred to the fact that the things which are inexplicable on the basis of individual experience might be explained by race experience. He imagined that this amounted to a final disposition of the controversy between empiricism and a priorism. He nevertheless perceives that in the find analysis he concedes the correctness of empiricisin,
