Whether the Souls of Brute Animals Are Subsistent?
Objection 1: It would seem that the souls of brute animals are
subsistent. For man is of the same genus as other animals; and,
as we have just shown (A. 2), the soul of man is subsistent.
Therefore the souls of other animals are subsistent.
Obj. 2: Further, the relation of the sensitive faculty to sensible
objects is like the relation of the intellectual faculty to
intelligible objects. But the intellect, apart from the body,
apprehends intelligible objects. Therefore the sensitive faculty,
apart from the body, perceives sensible objects. Therefore, since
the souls of brute animals are sensitive, it follows that they are
subsistent; just as the human intellectual soul is subsistent.
Obj. 3: Further, the soul of brute animals moves the body. But the
body is not a mover, but is moved. Therefore the soul of brute
animals has an operation apart from the body.
_On the contrary,_ Is what is written in the book De Eccl. Dogm. xvi,
xvii: "Man alone we believe to have a subsistent soul: whereas the
souls of animals are not subsistent."
_I answer that,_ The ancient philosophers made no distinction between
sense and intellect, and referred both to a corporeal principle, as
has been said (A. 1). Plato, however, drew a distinction between
intellect and sense; yet he referred both to an incorporeal
principle, maintaining that sensing, just as understanding, belongs
to the soul as such. From this it follows that even the souls of
brute animals are subsistent. But Aristotle held that of the
operations of the soul, understanding alone is performed without a
corporeal organ. On the other hand, sensation and the consequent
operations of the sensitive soul are evidently accompanied with
change in the body; thus in the act of vision, the pupil of the eye
is affected by a reflection of color: and so with the other senses.
Hence it is clear that the sensitive soul has no _per se_ operation
of its own, and that every operation of the sensitive soul belongs to
the composite. Wherefore we conclude that as the souls of brute
animals have no _per se_ operations they are not subsistent. For the
operation of anything follows the mode of its being.
Reply Obj. 1: Although man is of the same genus as other animals, he
is of a different species. Specific difference is derived from the
difference of form; nor does every difference of form necessarily
imply a diversity of genus.
Reply Obj. 2: The relation of the sensitive faculty to the sensible
object is in one way the same as that of the intellectual faculty to
the intelligible object, in so far as each is in potentiality to its
object. But in another way their relations differ, inasmuch as the
impression of the object on the sense is accompanied with change in
the body; so that excessive strength of the sensible corrupts sense;
a thing that never occurs in the case of the intellect. For an
intellect that understands the highest of intelligible objects is
more able afterwards to understand those that are lower. If, however,
in the process of intellectual operation the body is weary, this
result is accidental, inasmuch as the intellect requires the
operation of the sensitive powers in the production of the phantasms.
Reply Obj. 3: Motive power is of two kinds. One, the appetitive
power, commands motion. The operation of this power in the sensitive
soul is not apart from the body; for anger, joy, and passions of a
like nature are accompanied by a change in the body. The other motive
power is that which executes motion in adapting the members for
obeying the appetite; and the act of this power does not consist in
moving, but in being moved. Whence it is clear that to move is not an
act of the sensitive soul without the body.
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