600 



SCIENCE. 



[N. S. Vol. XX. No. 514. 



is true of every concrete case of knowledge 

 which we possess. Its detailed working 

 out would be a metaphysics of knowledge, 

 an epistemology. 



Since knowledge is the successful sys- 

 tematization of the implications which are 

 disclosed in things by virtue of conscious- 

 ness, a second logical problem of funda- 

 mental importance is the determination of 

 the most general types of implication with 

 the categories which underlie them. The 

 execution of this problem would naturally 

 involve, as subsidiary, the greater part of 

 formal and symbolic logic. Indeed, vital 

 doctrines of the syllogism, of definition, of 

 formal inference, of the calculus of classes 

 and propositions, of the logic of relations, 

 appear to be bound up ultimately with a 

 doctrine of categories; for it is only a 

 recognition of basal types of existence with 

 their implications, that can save these doc- 

 trines from mere formalism. These types 

 of existence or categories are not to be re- 

 garded as free creations or as the contribu- 

 tions of the mind to experience. There is 

 no 'deduction' of them possible. They 

 must be discovered in the actual progress 

 of knowledge itself, and I see no reason to 

 suppose that their number is necessarily 

 fixed, or that we should necessarily be in 

 possession of all of them. It is requisite, 

 however, that in every case categories 

 should be incapable of reduction to each 

 other. 



A doctrine of categories seems to me to 

 be of the greatest importance in the sys- 

 tematization of knowledge, for no problem 

 of relation is even statable correctly, before 

 the type of existence to which its terms be- 

 long has been first determined. I submit 

 one illustration to reinforce this general 

 statement, namely, the relation of mind to 

 body. If mind and body belong to the 

 same type of existence, we have one set of 

 problems on our hands, but if they do not, 

 we have an entirely different set. Yet vol- 



umes of discussion written on this subject 

 have abounded in confusion, simply be- 

 cause they have regarded mind and body 

 as belonging to radically different types 

 of existence and yet related in terms of the 

 type to which one of them belongs. The 

 doctrine of 'parallelism' is, perhaps, the 

 epitome of this confusion. 



The doctrine of categories will involve 

 not only the greater part of formal and 

 symbolic logic, but will undoubtedly carry 

 the logician into the doctrine of method. 

 Here it is to be hoped that recent tenden- 

 cies will result in effectively breaking down 

 the artificial distinctions which have pre- 

 vailed between deduction and induction. 

 Differences in method do not result from 

 differences in points of departure, or be- 

 tween the universal and the particular, but 

 from the categories, again, which give the 

 method direction and aim, and result in 

 different types of synthesis. In this direc- 

 tion, the logician may hope for an approxi- 

 mately correct classification of the various 

 departments of knowledge. Such a classi- 

 fication is, perhaps, the ideal of logical 

 theory. 



Frederick J. E. Woodbridge. 

 Columbia University. 



CLARENCE L. HEBBICK. 



The death of Professor Clarence L. Her- 

 rick September 15 in New Mexico was 

 noted in Science for September 23. In 

 him neurology and geology alike have lost 

 a brilliant investigator and a teacher of 

 rare power. 



His scientific work began in the high 

 school. During his college course at the 

 University of Minnesota, where he gradu- 

 ated in 1880, he was employed on the Nat- 

 ural History Survey of the state and for 

 five years following he was actively con- 

 nected with this work, completing a large 

 quarto on the Mammals of Minnesota in 

 1885. From 1884 to 1889 and again from 



