Whether There Can Be Any Habits in the Powers of the Sensitive Part?
Objection 1: It would seem that there cannot be any habits in the
powers of the sensitive part. For as the nutritive power is an
irrational part, so is the sensitive power. But there can be no
habits in the powers of the nutritive part. Therefore we ought not to
put any habit in the powers of the sensitive part.
Obj. 2: Further, the sensitive parts are common to us and the brutes.
But there are not any habits in brutes: for in them there is no will,
which is put in the definition of habit, as we have said above (Q.
49, A. 3). Therefore there are no habits in the sensitive powers.
Obj. 3: Further, the habits of the soul are sciences and virtues: and
just as science is related to the apprehensive power, so it virtue
related to the appetitive power. But in the sensitive powers there
are no sciences: since science is of universals, which the sensitive
powers cannot apprehend. Therefore, neither can there be habits of
virtue in the sensitive part.
_On the contrary,_ The Philosopher says (Ethic. iii, 10) that "some
virtues," namely, temperance and fortitude, "belong to the irrational
part."
_I answer that,_ The sensitive powers can be considered in two ways:
first, according as they act from natural instinct: secondly,
according as they act at the command of reason. According as they act
from natural instinct, they are ordained to one thing, even as nature
is; but according as they act at the command of reason, they can be
ordained to various things. And thus there can be habits in them, by
which they are well or ill disposed in regard to something.
Reply Obj. 1: The powers of the nutritive part have not an inborn
aptitude to obey the command of reason, and therefore there are no
habits in them. But the sensitive powers have an inborn aptitude to
obey the command of reason; and therefore habits can be in them: for
in so far as they obey reason, in a certain sense they are said to be
rational, as stated in _Ethic._ i, 13.
Reply Obj. 2: The sensitive powers of dumb animals do not act at the
command of reason; but if they are left to themselves, such animals
act from natural instinct: and so in them there are no habits
ordained to operations. There are in them, however, certain
dispositions in relation to nature, as health and beauty. But whereas
by man's reason brutes are disposed by a sort of custom to do things
in this or that way, so in this sense, to a certain extent, we can
admit the existence of habits in dumb animals: wherefore Augustine
says (QQ. lxxxiii, qu. 36): "We find the most untamed beasts,
deterred by fear of pain, from that wherein they took the keenest
pleasure; and when this has become a custom in them, we say that they
are tame and gentle." But the habit is incomplete, as to the use of
the will, for they have not that power of using or of refraining,
which seems to belong to the notion of habit: and therefore, properly
speaking, there can be no habits in them.
Reply Obj. 3: The sensitive appetite has an inborn aptitude to be
moved by the rational appetite, as stated in _De Anima_ iii, text.
57: but the rational powers of apprehension have an inborn aptitude
to receive from the sensitive powers. And therefore it is more
suitable that habits should be in the powers of sensitive appetite
than in the powers of sensitive apprehension, since in the powers of
sensitive appetite habits do not exist except according as they act
at the command of the reason. And yet even in the interior powers of
sensitive apprehension, we may admit of certain habits whereby man
has a facility of memory, thought or imagination: wherefore also the
Philosopher says (De Memor. et Remin. ii) that "custom conduces much
to a good memory": the reason of which is that these powers also are
moved to act at the command of the reason.
On the other hand the exterior apprehensive powers, as sight, hearing
and the like, are not susceptible of habits, but are ordained to
their fixed acts, according to the disposition of their nature, just
as the members of the body, for there are no habits in them, but
rather in the powers which command their movements.
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