4io POPULAR SCIENCE MONTHLY. 



of the origin of knowledge it is an extremely na'ive form of empiricism 

 and associationism. It is the old naive 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.* It is true Haeckel does incidentally speak 

 of innate knowledge a priori in connection with innate instincts, which 

 he explains as having originally been acquired empirically through race- 

 experience,! 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 what- 

 ever 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. \ Here we seem 

 to get a jumble of nearly all possible standpoints, of realism, semi- 

 realism 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, provis- 

 ional 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 § 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. "§ 

 We can prove its existence by electrical and optical experiments; 



* See ' Weltraethsel,' p. 141. 



tP. 144. 



% P. 283. 



I See Preface to ' Weltraethsel.' 



j| Pp. 260f. 



