6o4 THE POPULAR SCIENCE MONTHLY. 



It appears to us that, if a philosophy is to assume this role and to 

 undertake the guidance of man's thought and action, it must bring for- 

 ward general principles of such breadth that they will apply to all 

 orders of phenomena, from the simplest to the most complex a sys- 

 tem of laws coordinated by deductive relations, and by its univer- 

 sality expressing all the phenomena of the universe. "Whether these 

 general principles are given a priori, as the intuitionists hold, or 

 whether they are the abstract expression of an experience invariably 

 and unconditionally repeated, at all events they must be such that 

 from them all our scientific theories may be deduced ; they must ap- 

 pear in all our researches as the criterion of the truth of the results, and 

 they must underlie all our anticipations of truth as the guiding prin- 

 ciples. Causes, that is to say, the sum of the antecedent phenomena, 

 whose joint action is necessary for the production of the consequent 

 phenomenon, or effect, may be as diverse as you please, nevertheless 

 their relation to their efiect will be expressed by the same general 

 law. 



A philosophy of biology must reduce under these principles of 

 philosophy all the truths furnished by exiDcrience in the various 

 branches of investigation pertaining to that science; must explain 

 them by these principles; must present them to us as necessary, and 

 the contrary results as illogical and unphilosophical, so as to produce a 

 twofold eftect, viz., the highest possible harmony in the system of our 

 knowledges, and an ever-strengthening confirmation of the general 

 principles which are their abstract expression. We must demand of 

 it a verdict upon doctrines respecting the constitution of the living 

 individual and its origin and the constitution of the species to which 

 the individual belongs, which verdict shall oblige us to accept these 

 doctrines as corollaries of the same general princiiDles from which the 

 accepted theories of the other abstract sciences are likewise deduced. 

 Finally, we must derive from this philosophy of biology the assurance 

 that the generalizations which it offers to us ai-e grounds iipon which 

 we can stand securely in our deductions of course within the province 

 of biology respecting man and the human species. 



Mr. Herbert Spencer attempts something like this when he rests 

 the laws of biology upon the theory of changes in the course of things, 

 as set forth in his "First Principles." The "Principles of Biology" 

 is the first application of his system of philosophy to a highly-comj^lex 

 order of phenomena. 



It will be well to give a sketch of Mr. Spencer's whole system, so 

 that we maj'' better understand the meaning of the abstract terms he 

 employs, and the relations between the general laws on which the sys- 

 tem is based. We shall thus be in a position to appreciate the author's 

 application of his system to the more restricted field of biology. 



Underlying Spencer's system we find the principle of the persist- 

 ence of force, " the sole truth which transcends experience," to which 



