CHAPTER II 
CONSCIOUSNESS 
I.—TueE Conscious ACCOMPANIMENTS OF CERTAIN ORGANIC 
CHANGES 
Ir is possible that all organic behaviour is accompanied by 
consciousness. But there is no direct means of ascertaining 
whether it is so or not. This is, and must remain, a matter of 
more or less plausible conjecture. We have, indeed, no direct 
knowledge of any consciousness save our own. Undue stress 
should not, however, be laid on this fundamental isolation of 
the individual mind. We confidently infer that our fellow- 
men are conscious, because they are in all essential respects 
like us, and because they behave just as we do when we act 
under its guiding influence. And on similar grounds we 
believe not less confidently that many animals are also con- 
scious. But how far we are justified in extending this 
inference it is difficult to say. Probably our safest criterion 
is afforded by circumstantial evidence that the animal in 
question profits by experience. If, as we watch any given 
creature during its life-history, we see at first a number of 
congenital or acquired modes of behaviour, we may not be 
able to say whether they are accompanied by consciousness or 
not ; but if we find that some of these are subsequently carried 
out more vigorously while others are checked, we seem justified 
in the inference that pleasurable consciousness was associated 
with the results of the former, and disagreeable consciousness 
with those of the latter. When we see that a chick, for 
example, pecks at first at any small object, it is difficult to 
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