Preface 



method of treatment, secondary indeed but still important, 

 concerning which it is necessary to enter into some detail. 



In considering the different biological and psycho- 

 logical sciences, and in studying the inductions, deduc- 

 tions, and received hypotheses founded on their data 

 and accepted by most contemporary men of science, 

 I was struck by serious and obvious errors due to a 

 tendency to forget of the general method of treatment 

 above referred to. 



There is no single one of the main academic 

 hypotheses on evolution, on the physical or psychological 

 constitution of the individual, or on life and conscious- 

 ness, which is capable of adaptation to all the facts of 

 evolution, of physiology or of psychology; nor, a fortiori, 

 is there one which can embrace general and individual 

 evolution in a synthetic whole. 



Further, most of these hypotheses are, as I shall 

 demonstrate, certainly in opposition to at least some 

 well-established facts. 



In seeking the first origin and cause of these errors 

 in generalisation I have been led to discover them 

 pre-eminently in the choice of the primary facts on which 

 the framework of contemporary scientific philosophy 

 is based. 



In all sciences, and especially in biology and 

 psychology, facts selected with a synthetic conclusion 

 in view, may lead to antagonistic method, and con- 

 sequently to concepts which may be divergent or 

 even opposed. Two principal methods may be out- 

 lined, each resulting from the selection of primary 

 facts. 



The first of these methods starts from the principle 

 that science should always proceed from the simple to 

 the complex. This method, therefore, takes as its 

 point of departure the most elementary facts, endeavours 

 to understand them, then passes on to rather more 

 complex facts of the same order, applying to them the 



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