658 



SCIENCE. 



[N. S. Vol. XXIII. No. 591. 



such thing as necessity of thought, goes alto- 

 gether too far.' Bocher takes a middle posi- 

 tion, apparently holding to the validity of the 

 criterion of mental necessity or ultimate seK- 

 evidence, as such, but doubting whether we 

 can at any given time be sure that we can 

 apply that principle to any specified proposi- 

 tion: 



We must remember, when we are tempted to 

 put implicit confidence in certain fundamental 

 logical principles, that ... no very great 

 weight can be attached to the mere fact that these 

 principles appeal to us as obviously true; for 

 other modes of reasoning which are now uni- 

 versally recognized as faulty have appealed in 

 just this way to the greatest minds of the past. 



Ostwald, speaking of the conclusion that if 

 B follows A. and C follows B in any well- 

 ordered series, then C comes after A, says: 



The correctness and validity of this proposition 

 seems to us beyond all doubt. But this is only 

 a result of the fact that we are able to demon- 

 strate it very easily in countless single cases, 

 and have so demonstrated it. . . . To call such 

 a proposition, however, a necessity of thinking 

 does not appear to me correct. ... To base the 

 proof for the correctness of a proposition upon 

 the impossibility of thinking its opposite is an 

 impossible undertaking, because every kind of non- 

 sense can be thought. 



And Boltzmann deprecates an ' immoderate 

 trust in the so-called laws of thought': 



Our problem cannot be to quote [sic the trans- 

 lator] facts before the judgment seat of our laws 

 of thought, but to fit our mental representations 

 to the facts. 



Yet, somewhat oddly, Boltzmann is (in the 

 same paragraph) sure that 



in facts there can be no contradictions. As soon 

 as contradictions seems unavoidable we must test, 

 extend and modify that which we call laws of 

 thought, but which are [sic] only inherited, cus- 

 tomary representations, preserved for seons for 

 the description of practical needs. 

 As the requirement of non-contradiction is 

 itself commonly understood to be nothing but 

 the most fundamental of the laws of thought, 

 the paragraph seems to show that contradic- 

 tions are at any rate possible in the reasonings 

 of a great physicist — when he turns aside into 

 epistemology. The whole discussion of the 



question shows an vmdue amount of mental 

 confusion and divergence of view, which it 

 ought to be possible to get rid of, if philos- 

 ophers and men of science would generally 

 agree to study the history of philosophy un- 

 derstandingly and then ' get together ' for an 

 open-minded, patient, Socratic examination 

 of their own meanings and of one another's 

 views. 



On the relation of logic to psychology, 

 Taylor, Hammond and Woodbridge substan- 

 tially agree in — I can not but think — misap- 

 prehending the matter. All three, while 

 recognizing obvious points of contact, insist 

 that (in Hammond's phrase) ' the essence of 

 the logical problem is not touched by psy- 

 chology, and should not be mixed up with it,' 

 since psychology merely describes judgment 

 and other mental processes, while logic in- 

 quires concerning truth in judgments. ' The 

 psychological laws of the formation of con- 

 cepts and beliefs are exemplified equally in 

 the discovery and propagation of truth and 

 of error,' says Taylor. But surely the only 

 verifiable test of an absolutely true judgment 

 (if there be such a thing) is the subjective 

 fact that I can neither believe nor conceive 

 its opposite; or of a probable judgment, that 

 I find no adequate consideration which im- 

 pels me to believe its opposite. At any given 

 moment of inquiry, verifiable truth can, for 

 anybody, only mean unescapable belief ; proba- 

 bility can only mean belief conformable to 

 preponderating, experience-engendered mental 

 ease and habit. And the determination of 

 the general sort of mental content in the 

 presence of which such necessities of concep- 

 tion or deeply-rooted preferences of belief 

 arise is certainly nothing but a question of 

 introspective psychology. A normative prin- 

 ciple can only be a way of stating a peculiar 

 kind of descriptive fact, viz., a necessary (and 

 supposably imiversal) judgment-reaction ex- 

 hibited by the mind in the presence of certain 

 carefully analyzed meanings or ideational 

 content. This was not unfamiliar to Locke or 

 to Hume or to the Leibnitzians ; but it seems 

 of late to be too little considered. So, again, 

 Woodbridge's vigorous and well-written argu- 



