6 BRAIN MECHANISMS AND LEARNING 



System of Syiitlictic Philosophy, the successive parts of which appeared at 

 intervals through the balance of the nineteenth century. 



In the first edition of his Priiicipk'S of Psychohii^y, published in 1855, and 

 thus four years before the Orij^iii of Species, Spencer (1899) pointed out 

 that his arguments 'imply a tacit adhesion to the development hypothesis, 

 that Life in its multitudinous and infinitely varied embodiments has risen 

 out of the lowest and simplest beginnings, by steps as gradual as those 

 which evolve a homogenous, microscopic germ into a complex organism, 

 by progressive unbroken evolution, and through the instrumentality of 

 what we call natural causes. Save for those who still adhere to the Hebrew 

 myth or to the doctrine of special creation derived from it, there is no 

 alternative but this hypothesis or no hypothesis'. 



Applying his 'development hypothesis' to psychology, Spencer 

 reasoned: 'If the doctrine of Evolution is true, the inevitable implication 

 is that Mind can be understood only by observing how Mind is evolved. 

 If creatures of the most elevated kinds have reached those highly inte- 

 grated, very definite and extremely heterogeneous organizations they 

 possess, through modification upon modification accumulated during an 

 immeasurable past, if the developed nervous systems of such creatures 

 have gained their complex structure and functions little by little; then, 

 necessarily, the involved forms of consciousness, which are the correlates 

 of these complex structures and functions, must also have arisen by 

 degrees.' 



In the study of Mind, 'in its ascending gradations through the varic^us 

 types of sentient beings', Spencer conceived of 'a nascent Mind, possessed 

 by low types in which nerve centres are not yet clearly differentiated from 

 one another', and consisting of 'a confused sentiency formed of recurrent 

 pulses of feeling having but little variety or combination. At a stage above 

 this, while yet the organs of the higher senses are rudimentary. Mind is 

 present probably under the form of a few sensations which, like those 

 yielded by our own viscera, are simple, vague and incoherent. From this 

 upwards, mental evolution exhibits a difterentiation of these simple 

 feelings into the more numerous kinds which the special senses yield; an 

 ever increasing integration of such more varied feelings, an ever increasing 

 multiformity in the aggregates of feelings produced, and an ever increas- 

 ing distinctness of structure in such aggregates; that is to say, there goes on 

 subjectively a change from an indefinite, incoherent homogeneity to a 

 definite, coherent heterogeneity. 



Support for his views was marshalled also from pharmacological 

 observations, when Spencer presented, in remarkably vivid detail, the 



