Objection 1: It would seem that irrational animals intend the end. For in things void of reason nature stands further apart from the rational nature, than does the sensitive nature in irrational animals. But nature intends the end even in things void of reason, as is proved in Phys. ii, 8. Much more, therefore, do irrational animals intend the end.
Obj. 2: Further, just as intention is of the end, so is enjoyment. But enjoyment is in irrational animals, as stated above (Q. 11, A. 2). Therefore intention is too.
Obj. 3: Further, to intend an end belongs to one who acts for an end; since to intend is nothing else than to tend to something. But irrational animals act for an end; for an animal is moved either to seek food, or to do something of the kind. Therefore irrational animals intend an end.
On the contrary, Intention of an end implies ordaining something to an end: which belongs to reason. Since therefore irrational animals are void of reason, it seems that they do not intend an end.
I answer that, As stated above (A. 1), to intend is to tend to something; and this belongs to the mover and to the moved. According, therefore, as that which is moved to an end by another is said to intend the end, thus nature is said to intend an end, as being moved to its end by God, as the arrow is moved by the archer. And in this way, irrational animals intend an end, inasmuch as they are moved to something by natural instinct. The other way of intending an end belongs to the mover; according as he ordains the movement of something, either his own or another's, to an end. This belongs to reason alone. Wherefore irrational animals do not intend an end in this way, which is to intend properly and principally, as stated above (A. 1).
Reply Obj. 1: This argument takes intention in the sense of being moved to an end.
Reply Obj. 2: Enjoyment does not imply the ordaining of one thing to another, as intention does, but absolute repose in the end.
Reply Obj. 3: Irrational animals are moved to an end, not as though they thought that they can gain the end by this movement; this belongs to one that intends; but through desiring the end by natural instinct, they are moved to an end, moved, as it were, by another, like other things that are moved naturally.