Summa contra Gentiles3.93 Chapter XCIII. Is there such a thing as fate, and what is it?

We may gather from the foregoing what we should think about fate. For observing that many things happen in this world accidentally, if particular causes be taken into consideration, some have maintained that such things are not subordinate to any superior causes. According to this opinion there is no such thing as fate. Others, however, endeavoured to refer such things to certain higher causes, asserting that they are directed thereby so as to proceed from them in orderly fashion. These held that there is fate, as though things which appear to happen by chance were effata, that is foretold or preordained by someone.

Some of these pretended to ascribe all contingent occurrences of this world to the causality of heavenly bodies, not excluding human elections, and they held that all such things are subject to the directing force of the stars, which force they called fate. This opinion is impossible and contrary to faith, as we have already shown.

Others, however, wished to assign to the direction of divine providence, all such things as appear to happen by chance in this lower world. Wherefore they maintained that all these things are subject to fate, this being the name given by them to the disposition which divine providence causes to be in things. Hence Boethius says that fate is a disposition inherent to changeable things, by which providence connects each one with its proper order. In this definition disposition stands for order; the words inherent to things are included to differentiate fate from providence, because the order as existing in the divine mind and not yet impressed on things is providence, but as already expressed in things, is called fate; changeable is added to show that the order of providence does not deprive things of contingency and changeableness, as some maintained.

In this sense to deny fate is to deny divine providence. Since, however, we should not use even names in common with unbelievers, lest use of the same expressions lead us into error: the faithful should not use the word fate, lest they seem to agree with those who having false notions about fate, subject all things to the force of the stars. Hence Augustine says (De Civ. Dei, v., i): If anyone gives the name of fate to God’s will or power, let him keep his opinion, but hold his tongue: and Gregory in the same sense says: Far be it from the minds of the faithful to think that fate is anything real.