Whether Any Habit Is Caused by Acts?
Objection 1: It would seem that no habit is caused by acts. For habit
is a quality, as we have said above (Q. 49, A. 1). Now every quality
is caused in a subject, according to the latter's receptivity. Since
then the agent, inasmuch as it acts, does not receive but rather
gives: it seems impossible for a habit to be caused in an agent by
its own acts.
Obj. 2: Further, the thing wherein a quality is caused is moved to
that quality, as may be clearly seen in that which is heated or
cooled: whereas that which produces the act that causes the quality,
moves, as may be seen in that which heats or cools. If therefore
habits were caused in anything by its own act, it would follow that
the same would be mover and moved, active and passive: which is
impossible, as stated in Physics iii, 8.
Obj. 3: Further, the effect cannot be more noble than its cause. But
habit is more noble than the act which precedes the habit; as is
clear from the fact that the latter produces more noble acts.
Therefore habit cannot be caused by an act which precedes the habit.
_On the contrary,_ The Philosopher (Ethic. ii, 1, 2) teaches that
habits of virtue and vice are caused by acts.
_I answer that,_ In the agent there is sometimes only the active
principle of its act: for instance in fire there is only the active
principle of heating. And in such an agent a habit cannot be caused
by its own act: for which reason natural things cannot become
accustomed or unaccustomed, as is stated in _Ethic._ ii, 1. But a
certain agent is to be found, in which there is both the active and
the passive principle of its act, as we see in human acts. For the
acts of the appetitive power proceed from that same power according
as it is moved by the apprehensive power presenting the object: and
further, the intellective power, according as it reasons about
conclusions, has, as it were, an active principle in a self-evident
proposition. Wherefore by such acts habits can be caused in their
agents; not indeed with regard to the first active principle, but
with regard to that principle of the act, which principle is a mover
moved. For everything that is passive and moved by another, is
disposed by the action of the agent; wherefore if the acts be
multiplied a certain quality is formed in the power which is passive
and moved, which quality is called a habit: just as the habits of
moral virtue are caused in the appetitive powers, according as they
are moved by the reason, and as the habits of science are caused in
the intellect, according as it is moved by first propositions.
Reply Obj. 1: The agent, as agent, does not receive anything. But
in so far as it moves through being moved by another, it receives
something from that which moves it: and thus is a habit caused.
Reply Obj. 2: The same thing, and in the same respect, cannot be
mover and moved; but nothing prevents a thing from being moved by
itself as to different respects, as is proved in Physics viii, text.
28, 29.
Reply Obj. 3: The act which precedes the habit, in so far as
it comes from an active principle, proceeds from a more excellent
principle than is the habit caused thereby: just as the reason is a
more excellent principle than the habit of moral virtue produced in
the appetitive power by repeated acts, and as the understanding of
first principles is a more excellent principle than the science of
conclusions.
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