18 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



but there are several objects of search which are regarded 

 as such by most men of science ; amongst these may be 

 mentioned perpetual motion, the creation or destruction of 

 matter, energy, &c. But how are we to judge of what is 

 absolutely impossible, and what is not ? As our reasoning 

 faculty is finite, and we have therefore no infallible guide, 

 our best course is to consider those objects of search im- 

 possible which distinctly contradict any of what are 

 termed the fundamental ' laws of thought,' l or those of 

 science. A thing either is or is not. That which is, is. 

 That only which exists, or which is possible to exist in 

 accordance with the essential nature of things, can be 

 discovered. A self-contradictory statement, such as that 

 which is is not, or the largest planets are the smallest, 

 cannot be true. Two contradictory statements or hypo- 

 theses also cannot both be true. A whole is greater than 

 its part. Things equal to the same are equal to each 

 other. There can be no square root to a negative quan- 

 tity. A figure which possesses three equal sides must 

 have three equal angles. A substance cannot be and not 

 be at the same time in the same place. Every effect 

 must have a cause. We cannot create or destroy either 

 matter or energy. Action and reaction are equal and 

 contrary. Two mutually destructive actions cannot co- 

 exist. A body cannot be moving in opposite directions 

 at the same time, &c. All of these are fundamental 

 statements, the contrary of which are considered abso- 

 lutely untrue and impossible by all scientific men. As an 

 approximation, therefore, to a criterion of scientific truth, 

 we may say, it is that which does not contradict any of 

 what are termed the fundamental 'laws of thought' or 



1 See Boole's Laws of Thouqlit ; Jevons's Principles of Science, vol. i. 

 ./ p. 6 ; Thomson's Outlines of the Laws of TJwught. Compare also the 

 chapter on ' The Criteria of Scientific Truth.' 



