676 HENRY A. ROWLAND 



All the facts which we have considered, the liability to error in what- 

 ever direction we go, the infirmity of our minds in their reasoning 

 power, the fallibility of witnesses and experimenters, lead the scientist 

 to be specially skeptical with reference to any statement made to him 

 or any so-called knowledge which may be brought to his attention. The 

 facts and theories of our science are so much more certain than those of 

 history, of the testimony of ordinary people on which the facts of 

 ordinary history or of legal evidence rest, or of the value of medicines to 

 which we trust when we are ill, indeed to the whole fabric of supposed 

 truth by which an ordinary person guides his belief and the actions of 

 his life, that it may seem ominous and strange if what I have said of 

 the imperfections of the knowledge of physics is correct. How shall we 

 regulate our minds with respect to it: there is only one way that I 

 know of and that is to avoid the discontinuity of the ordinary, indeed 

 the so-called cultivated legal mind. There is no such thing as absolute 

 truth and absolute falsehood. The scientific mind should never recog- 

 nize the perfect truth or the perfect falsehood of any supposed theory 

 or observation. It should carefully weigh the chances of truth and 

 error and grade each in its proper position along the line joining abso- 

 lute truth and absolute error. 



The ordinary crude mind has only two compartments, one for truth 

 and one for error; indeed the contents of the two compartments are 

 sadly mixed in most cases: the ideal scientific mind, however, has an 

 infinite number. Each theory or law is in its proper compartment indi- 

 cating the probability of its truth. As a new fact arrives the scientist 

 changes it from one compartment to another so as, if possible, to always 

 keep it in its proper relation to truth and error. Thus the fluid nature 

 of electricity was once in a compartment near the truth. Faraday's and 

 Maxwell's researches have now caused us to move it to a compartment 

 nearly up to that of absolute error. 



So the law of gravitation within planetary distances is far toward 

 absolute truth, but may still need amending before it is advanced farther 

 in that direction. 



The ideal scientific mind, therefore, must always be held in a state 

 of balance which the slightest new evidence may change in one direction 

 or another. It is in a constant state of skepticism, knowing full well 

 that nothing is certain. It is above all an agnostic with respect to all 

 facts and theories of science as well as to all other so-called beliefs and 

 theories. 



Yet it would be folly to reason from this that we need not guide our 



