Objection 1. It seems that men are not predestined by God, for Damascene says (De Fide Orth. ii, 30): "It must be borne in mind that God foreknows but does not predetermine everything, since He foreknows all that is in us, but does not predetermine it all." But human merit and demerit are in us, forasmuch as we are the masters of our own acts by free will. All that pertains therefore to merit or demerit is not predestined by God; and thus man's predestination is done away.
Objection 2. Further, all creatures are directed to their end by divine providence, as was said above (22, 1, 2). But other creatures are not said to be predestined by God. Therefore neither are men.
Objection 3. Further, the angels are capable of beatitude, as well as men. But predestination is not suitable to angels, since in them there never was any unhappiness (miseria); for predestination, as Augustine says (De praedest. sanct. 17), is the "purpose to take pity [miserendi]" [See 22, 3]. Therefore men are not predestined.
Objection 4. Further, the benefits God confers upon men are revealed by the Holy Ghost to holy men according to the saying of the Apostle (1 Corinthians 2:12): "Now we have received not the spirit of this world, but the Spirit that is of God: that we may know the things that are given us from God." Therefore if man were predestined by God, since predestination is a benefit from God, his predestination would be made known to each predestined; which is clearly false.
On the contrary, It is written (Romans 8:30): "Whom He predestined, them He also called."
I answer that, It is fitting that God should predestine men. For all things are subject to His providence, as was shown above (Question 22, Article 2). Now it belongs to providence to direct things towards their end, as was also said (22, 1, 2). The end towards which created things are directed by God is twofold; one which exceeds all proportion and faculty of created nature; and this end is life eternal, that consists in seeing God which is above the nature of every creature, as shown above (Question 12, Article 4). The other end, however, is proportionate to created nature, to which end created being can attain according to the power of its nature. Now if a thing cannot attain to something by the power of its nature, it must be directed thereto by another; thus, an arrow is directed by the archer towards a mark. Hence, properly speaking, a rational creature, capable of eternal life, is led towards it, directed, as it were, by God. The reason of that direction pre-exists in God; as in Him is the type of the order of all things towards an end, which we proved above to be providence. Now the type in the mind of the doer of something to be done, is a kind of pre-existence in him of the thing to be done. Hence the type of the aforesaid direction of a rational creature towards the end of life eternal is called predestination. For to destine, is to direct or send. Thus it is clear that predestination, as regards its objects, is a part of providence.
Reply to Objection 1. Damascene calls predestination an imposition of necessity, after the manner of natural things which are predetermined towards one end. This is clear from his adding: "He does not will malice, nor does He compel virtue." Whence predestination is not excluded by Him.
Reply to Objection 2. Irrational creatures are not capable of that end which exceeds the faculty of human nature. Whence they cannot be properly said to be predestined; although improperly the term is used in respect of any other end.
Reply to Objection 3. Predestination applies to angels, just as it does to men, although they have never been unhappy. For movement does not take its species from the term "wherefrom" but from the term "whereto." Because it matters nothing, in respect of the notion of making white, whether he who is made white was before black, yellow or red. Likewise it matters nothing in respect of the notion of predestination whether one is predestined to life eternal from the state of misery or not. Although it may be said that every conferring of good above that which is due pertains to mercy; as was shown previously (21, 3 and 4).
Reply to Objection 4. Even if by a special privilege their predestination were revealed to some, it is not fitting that it should be revealed to everyone; because, if so, those who were not predestined would despair; and security would beget negligence in the predestined.
Source: Summa Theologica (New Advent)