Whether fate is unchangeable?
Objection 1: It seems that fate is not unchangeable. For Boethius says (De Consol. iv): "As reasoning is to the intellect, as the begotten is to that which is, as time to eternity, as the circle to its centre; so is the fickle chain of fate to the unwavering simplicity of Providence."
Objection 2: Further, the Philosopher says (Topic. ii, 7): "If we be moved, what is in us is moved." But fate is a "disposition inherent to changeable things," as Boethius says (De Consol. iv). Therefore fate is changeable.
Objection 3: Further, if fate is unchangeable, what is subject to fate happens unchangeably and of necessity. But things ascribed to fate seem principally to be contingencies. Therefore there would be no contingencies in the world, but all things would happen of necessity.
On the contrary, Boethius says (De Consol. iv) that fate is an unchangeable disposition.
I answer that, The disposition of second causes which we call fate, can be considered in two ways: firstly, in regard to the second causes, which are thus disposed or ordered; secondly, in regard to the first principle, namely, God, by Whom they are ordered. Some, therefore, have held that the series itself or dispositions of causes is in itself necessary, so that all things would happen of necessity; for this reason that each effect has a cause, and given a cause the effect must follow of necessity. But this is false, as proved above (Q[115], A[6]).
Others, on the other hand, held that fate is changeable, even as dependent on Divine Providence. Wherefore the Egyptians said that fate could be changed by certain sacrifices, as Gregory of Nyssa says (Nemesius, De Homine). This too has been disproved above for the reason that it is repugnant to Divine Providence.
We must therefore say that fate, considered in regard to second causes, is changeable; but as subject to Divine Providence, it derives a certain unchangeableness, not of absolute but of conditional necessity. In this sense we say that this conditional is true and necessary: "If God foreknew that this would happen, it will happen." Wherefore Boethius, having said that the chain of fate is fickle, shortly afterwards adds---"which, since it is derived from an unchangeable Providence must also itself be unchangeable."
From this the answers to the objections are clear.
Whether all things are subject to fate?
Objection 1: It seems that all things are subject to fate. For Boethius says (De Consol. iv): "The chain of fate moves the heaven and the stars, tempers the elements to one another, and models them by a reciprocal transformation. By fate all things that are born into the world and perish are renewed in a uniform progression of offspring and seed." Nothing therefore seems to be excluded from the domain of fate.
Objection 2: Further, Augustine says (De Civ. Dei v, 1) that fate is something real, as referred to the Divine will and power. But the Divine will is cause of all things that happen, as Augustine says (De Trin. iii, 1 seqq.). Therefore all things are subject to fate.
Objection 3: Further, Boethius says (De Consol. iv) that fate "is a disposition inherent to changeable things." But all creatures are changeable, and God alone is truly unchangeable, as stated above (Q[9], A[2]). Therefore fate is in all things.
On the contrary, Boethius says (De Consol. iv) that "some things subject to Providence are above the ordering of fate."
I answer that, As stated above (A[2]), fate is the ordering of second causes to effects foreseen by God. Whatever, therefore, is subject to second causes, is subject also to fate. But whatever is done immediately by God, since it is not subject to second causes, neither is it subject to fate; such are creation, the glorification of spiritual substances, and the like. And this is what Boethius says (De Consol. iv): viz. that "those things which are nigh to God have a state of immobility, and exceed the changeable order of fate." Hence it is clear that "the further a thing is from the First Mind, the more it is involved in the chain of fate"; since so much the more it is bound up with second causes.
Reply to Objection 1: All the things mentioned in this passage are done by God by means of second causes; for this reason they are contained in the order of fate. But it is not the same with everything else, as stated above.
Reply to Objection 2: Fate is to be referred to the Divine will and power, as to its first principle. Consequently it does not follow that whatever is subject to the Divine will or power, is subject also to fate, as already stated.
Reply to Objection 3: Although all creatures are in some way changeable, yet some of them do not proceed from changeable created causes. And these, therefore, are not subject to fate, as stated above.