Whether Many Habits Can Be in One Power?
Objection 1: It would seem that there cannot be many habits in one
power. For when several things are distinguished in respect of the
same thing, if one of them be multiplied, the others are too. Now
habits and powers are distinguished in respect of the same thing,
viz. their acts and objects. Therefore they are multiplied in like
manner. Therefore there cannot be many habits in one power.
Obj. 2: Further, a power is a simple force. Now in one simple subject
there cannot be diversity of accidents; for the subject is the cause
of its accidents; and it does not appear how diverse effects can
proceed from one simple cause. Therefore there cannot be many habits
in one power.
Obj. 3: Further, just as the body is informed by its shape, so is a
power informed by a habit. But one body cannot be informed at the
same time by various shapes. Therefore neither can a power be
informed at the same time by many habits. Therefore several habits
cannot be at the same time in one power.
_On the contrary,_ The intellect is one power; wherein, nevertheless,
are the habits of various sciences.
_I answer that,_ As stated above (Q. 49, A. 4), habits are
dispositions of a thing that is in potentiality to something, either
to nature, or to operation, which is the end of nature. As to those
habits which are dispositions to nature, it is clear that several can
be in one same subject: since in one subject we may take parts in
various ways, according to the various dispositions of which parts
there are various habits. Thus, if we take the humors as being parts
of the human body, according to their disposition in respect of human
nature, we have the habit or disposition of health: while, if we take
like parts, such as nerves, bones, and flesh, the disposition of
these in respect of nature is strength or weakness; whereas, if we
take the limbs, i.e. the hands, feet, and so on, the disposition of
these in proportion to nature, is beauty: and thus there are several
habits or dispositions in the same subject.
If, however, we speak of those habits that are dispositions to
operation, and belong properly to the powers; thus, again, there may
be several habits in one power. The reason for this is that the
subject of a habit is a passive power, as stated above (Q. 51, A. 2):
for it is only an active power that cannot be the subject of a habit,
as was clearly shown above (Q. 51, A. 2). Now a passive power is
compared to the determinate act of any species, as matter to form:
because, just as matter is determinate to one form by one agent, so,
too, is a passive power determined by the nature of one active object
to an act specifically one. Wherefore, just as several objects can
move one passive power, so can one passive power be the subject of
several acts or perfections specifically diverse. Now habits are
qualities or forms adhering to a power, and inclining that power to
acts of a determinate species. Consequently several habits, even as
several specifically different acts, can belong to one power.
Reply Obj. 1: Even as in natural things, diversity of species is
according to the form, and diversity of genus, according to matter,
as stated in _Metaph._ v, text. 33 (since things that differ in
matter belong to different genera): so, too, generic diversity of
objects entails a difference of powers (wherefore the Philosopher
says in _Ethic._ vi, 1, that "those objects that differ generically
belong to different departments of the soul"); while specific
difference of objects entails a specific difference of acts, and
consequently of habits also. Now things that differ in genus differ
in species, but not vice versa. Wherefore the acts and habits of
different powers differ in species: but it does not follow that
different habits are in different powers, for several can be in one
power. And even as several genera may be included in one genus, and
several species be contained in one species; so does it happen that
there are several species of habits and powers.
Reply Obj. 2: Although a power is simple as to its essence, it is
multiple virtually, inasmuch as it extends to many specifically
different acts. Consequently there is nothing to prevent many
superficially different habits from being in one power.
Reply Obj. 3: A body is informed by its shape as by its own
terminal boundaries: whereas a habit is not the terminal boundary of a
power, but the disposition of a power to an act as to its ultimate
term. Consequently one same power cannot have several acts at the same
time, except in so far as perchance one act is comprised in another;
just as neither can a body have several shapes, save in so far as one
shape enters into another, as a three-sided in a four-sided figure.
For the intellect cannot understand several things at the same time
_actually;_ and yet it can know several things at the same time
_habitually._
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