THE THEORY OF USE-INHERITANCE. rer gs: 
in germ, the knowledge of space; that this knowledge has 
grown with the correlated structures of the brain, which 
condition sensations and their connection; and that thus 
_at last our present knowledge of space has emerged. Here, 
it is the first step that costs. The initial difficulty of this 
hypothesis, as of the empirical theory which it has sup- 
planted, is to show that our knowledge of space can be 
analysed into sensations. The motor sensations are, no 
doubt, conditions of our knowledge of space, and of objects 
as spatial; but I cannot see that sensations, which are 
mental facts, and therefore non-spatial, can contain in them- 
selves either space or our knowledge of it. The question is 
too large to be discussed here; but the burden of proof lies 
on those who maintain the theory, and in any such account 
of the genesis of our knowledge of space it is easy, I think, 
to detect the petitio principir. There has been a recurring 
tendency to suppose that, because sensations are the “first 
things in consciousness,” all that follows can be resolved into 
sensations. But, however true it may be that motor sensa- 
tions precede, and condition, the knowledge of space, the 
analysis into sensations fails. And this difficulty is not 
overcome by pushing it into the obscurity of the past. 
Again, it has been held that our belief in the universality 
of causation has resulted, not only from orderly sequences 
observed by the individual, but from similar sequences which 
have impressed themselves on the nervous systems of our 
ancestors, the expectation of the recurrence of phenomena 
growing stronger as it is transmitted through generation 
after generation. It is here assumed that the extraorganic 
world, the organism, and the mind itself, obey the law of 
cause and effect. The law of universal causation is thus 
taken for granted as clearly as it is by the physicist or the 
a priort philosopher. ‘It is evident that the law cannot be 
validated by a theory which presupposes it. But, assuming 
the objective validity of the law, is it possible to account thus 
for our belief in it? I think not. The occurrence of observed 
sequences, however uniform, could give no security for their 
orderly recurrence in the future and the remote; and a 
blind expectation, based on habit, whether personal or an- 
cestral, is really not what we mean by our belief that every 
event must have a cause. And it is far from the truth to 
represent the orderly sequences of nature as simply mirror- 
ing themselves in the mind of man through sense, and thus, 
through frequent repetition, being recorded in the organism. 
The orderly world of our experience is due, in no small 
measure, to our own construction. The sensations which we 
