of the origin of knowledge it is an extremely naïve form of empiricism and associationism. It is the old naïve story about sensations putting themselves together and forming ideas, of ideas putting themselves together and forming thought, personality, and all the other higher processes of consciousness.[1] It is true Haeckel does incidentally speak of innate knowledge à priori in connection with innate instincts, which he explains as having originally been acquired empirically through raceexperience,[2] but, so far as I see, this view does not affect his theory. Haeckel's empiricism is as unsatisfactory as it is simple, and has about as much value as the old theory of creation has in Haeckel's own science. Kant and modern epistemology seem to have made no impression whatever upon the great German biologist.
With respect to the problem of the nature of knowledge Haeckel's position is somewhat vacillating. He tells us that we do not know the irmer essence of things in themselves; indeed, he afterwards hints that perhaps there are no such things in themselves for all we know. At the same time space and time are realities, objective realities, real entities: the existence of space and time is now definitely proved.[3] Here we seem to get a jumble of nearly all possible standpoints, of realism, semirealism and idealism—one after another. That is (1) there is a thing in itself; we do not know its essence, however, but only its effects upon us; (2) for all we know there may be no thing in itself, we do not know and we do not care, we can get along without it; (3) space and time are realities, that is, either things in themselves or the attributes of things in themselves.
The same uncertainty prevails with respect to another point. Haeckel is a dogmatist and sceptic by turns, as the occasion suits him. We cannot know everything with certainty, we cannot get along without faith in science. The theories of science are articles of faith, provisional assumptions which may be overthrown at any time. Among such hypotheses Haeckel enumerates nearly all the great theories of the different sciences and also his own philosophical system[4] But this humility is merely a passing stage with our philosopher; his attitude is generally dogmatic; the tone of his book is that of a man who is absolutely sure of his result. Thus after having told us that certainty is impossible in science, that we must fill the gaps in our knowledge by faith, he declares dogmatically that the existence of ether, cosmo-ether, as real matter, is to-day a positive fact and not a mere hypothesis. [5] We can prove its existence by electrical and optical experiments;
