THE PRINCIPLES OF SCIENCE 205 



potentially falsifiable, we arrive at one belief we can hold compara- 

 tively certain simply because it has survived submission to the many 

 tests that have discredited all known alternative beliefs. However 

 "negative" this approach to scientific truth, it— and it alone— can jus- 

 tify the positive affirmation of Mill's ringing declaration: 



The beliefs which we have most warrant for, have no safeguard to rest 

 on, but a standing invitation to the whole world to prove them un- 

 founded. If the challenge is not accepted, or is accepted and the at- 

 tempt fails, we are far enough from certainty still; but we have done 

 the best that the existing state of human reason admits of ; . . . and 

 in the meantime we may rely on having attained such approach to 

 truth, as is possible in our own day. This is the amount of certainty 

 attainable by a fallible being, and this the sole way of attaining it. 



We here approach a characterization of science in negative terms. 

 It is a method of rejection that invests science with the extraordinary 

 power for self -correction Cohen holds to be decisive. 



The apodictic certainty of science is not the absolute certainty of any 

 specific result or material proposition, but the dialectic demonstration 

 that any inaccuracy or false step can be corrected only by relying on 

 principles inherent in the system of science itself. This is a position 

 unassailable by any argument that can pretend to have any evidence 

 in its favor. 



Plainly a purely negative system cannot suffice. Any expectation of 

 progress through a method of rejection must always presuppose a 

 positive production of new items thus to be winnowed. However, the 

 human mind seems quite competent to produce new scientific ideas, 

 and its competence most seriously impaired by unavailability or un- 

 acceptability of a reliable criterion of rejection. We are most stim- 

 ulated to produce new ideas by recognition of the inadequacy of 

 ideas we have earlier accepted. Thus for science the negative capac- 

 ity to court, recognize, and reject error is in itself precious. The char- 

 acteristically strong development of that faculty in science is indeed 

 the wellspring nourishing tlie root of scientific progressivism. 



No longer do we expect science to reach any bedrock of absolutely 

 secure knowledge. Today's conception of science, as endless frontier, 

 was grasped by Bernard a century ago. 



When we propound a general theory in our sciences, we are sure only 

 that, literally speaking, all such theories are false. They are only par- 



