g, infer distant appearances from near
ones, but not vice versa. All men look alike when they are a mile away,
hence when we see a man a mile off we cannot tell what he will look like
when he is only a yard away. But when we see him a yard away, we can
tell what he will look like a mile away. Thus the nearer view gives us
more valuable information, and the distant view is causally dependent
upon it in a sense in which it is not causally dependent upon the
distant view.

It is this greater causal potency of the near appearance that leads
physics to state its causal laws in terms of that system of regular
appearances to which the nearest appearances increasingly approximate,
and that makes it value information derived from the microscope or
telescope. It is clear that our sensations, considered as irregular
appearances of physical objects, share the causal dependence belonging
to comparatively distant appearances; therefore in our sensational life
we are in causal dependence upon physical laws.

This, however, is not the most important or interesting part of our
question. It is the causation of images that is the vital problem. We
have seen that they are subject to mnenic causation, and that mnenic
causation may be reducible to ordinary physical causation in nervous
tissue. This is the question upon which our attitude must turn towards
what may be called materialism. One sense of materialism is the view
that all mental phenomena are causally dependent upon physical phenomena
in the above-defined sense of causal dependence. Whether this is the
case or not, I do not profess to know. The question seems to me the
same as the question whether mnemic causation is ultimate, which we
considered without deciding in Lecture IV. But I think the bulk of the
evidence points to the materialistic answer as the more probable.

In considering the causal laws of psychology, the distinction between
rough generalizations and exact laws is important. There are many rough
generalizations in psychology, not only of the sort by which we
govern our ordinary behaviour to each other, but also of a more nearly
scientific kind. Habit and association belong among such laws. I will
give an illustration of the kind of law that can be obtained. Suppose a
person has frequently experienced A and B in close temporal contiguity,
an association will be established, so that A, or an image of A, tends
to cause an image of B. The question arises: will the asso