J.—PSYCHOLOGY 177 
special sensory organs, local cortical areas, inhibition centres, association 
fibres, resistance at synapses, drainage of neural energy, and so on. 
There can be no doubt that some of these concepts are illuminating for 
psychology, but again at the price of abandoning the purely empirical 
standpoint in the first sense of the term, and borrowing from experience 
other than sensory in order to make explanatory use of them. And indeed 
the experience from which the loan is taken is precisely that for which 
no physiological explanatory concepts are available. While we may 
accept engrams as the physiological reading of retentiveness, association 
fibres as correlated with the linkages between ideas, and the like, there 
is no suggestion forthcoming from physiology as to what may be the 
physiological bases of becoming aware of experience, abstracting relations, 
producing correlates, the volitional control of mental process, or the 
intimate and immediate awareness of self. Moreover, some of the 
physiological concepts in question have in the first instance simply been 
taken over from psychology, others are yet very speculative and uncertain, 
while others again, plausible enough in hypothesis, would by most ortho- 
dox physiologists themselves be rejected, as, for instance, those of the 
Gestalt theoricians. Still the very fact that these last have been seriously 
put forward shows how little definitely ascertained physiological knowledge 
is as yet of use in explanation of mental events. 
In any case, the physiological phenomena, like the physical ones, do not 
contain the principles of their own explanation within themselves. When 
we examine the segmentation of a cell under a microscope, we conceive of 
it as a process going on in an existent, material and unitary thing. Whence 
do those concepts of existence, matter, unity and thinghood, come? Cer- 
tainly not, I suggest, from the observed visual phenomena. When we 
stimulate the nerve of a nerve-muscle preparation and notice a contraction 
of the muscle, we conceive of the event asacausalone. Whence did we 
derive our notion of cause? Not, again I suggest, from the observed 
sequence. When we measure the intake and output of a living organism, 
we do so in terms of energy. From what experience is that concept of 
energy taken? Again, not from any one, nor from the sum total of 
observations involved in the measurements. All these and like beliefs 
with regard to physiological processes, and in particular in respect of 
their connection with mental events, are inferences from the phenomena, 
made in virtue of experiences of another kind. Physiology, accordingly, 
like physics, is an empirical science in the first sense because it concerns 
itself with certain selected sensory data ; in so far as it is explanatory, it 
is an inferential science. It is none the worse for that, however, even if 
it must borrow some of its concepts from psychology. ‘The point is that, 
generally without acknowledgment, it does so borrow from psychology 
in order to establish the very constructions it offers to reloan to that 
science as explanations of mental events. 
PsYCHOLOGY AS SCIENCE OF EXPERIENCE. 
We turn now to psychology, the most empirical of all the sciences in 
the sense that it deals directly with experience as such, makes no partial 
selection, but embraces all experiences alike indifferently, and at their 
