I. Contingency in things
Reportatio IA, dd. 39–40, qq. 1–3, nn. 24–59 The nature and cause of contingency 24 To answer these questions1 we must deal with four preliminary issues: first, whether there is contingency in things; second, given that there is, we need to determine the first cause of contingency; third, we must show how the primary basis of contingency can be found in God; and fourth, we need to clarify certain propositions that arise in this discussion.
I. Contingency in things 25 As for the first issue, it is important to note that there are two sorts of contingency in things, just as, by contrast, there are two sorts of necessity: there is necessity of immutability and necessity of inevitability. Necessity of immutability characterizes something that cannot be otherwise: for example, God is a necessary being in this way. By contrast, necessity of inevitability is the kind of necessity at issue when we say that some future event is inevitable, even though it is not immutable or necessary in itself: for example, that the sun will rise tomorrow is necessary with the necessity of inevitability, and other natural motions are necessary in this same way; and yet they can be otherwise, and therefore they are not unqualifiedly necessary or immutable.
26 In the same way, there are, by contrast, two sorts of contingency in things. There is contingency of mutability, in virtue of which something can in itself be otherwise: movable and corporeal things are contingent in this way. And there is contingency of evitability, which characterizes things whose outcome and existence can be avoided and impeded: all acts of will that are freely caused by the will are like this.
27 And these two contingencies are not the same, because not everything that is contingent in the first way—for example, something generable, which is contingent
1 Q. 1, "Does God immutably know future contingent events?"; q. 2, "Does God necessarily know future contingent events?"; q. 3, "Is it possible for someone predestinate to be damned?"
REPORTATIO IA, DD. –, QQ. –, NN. –
in itself—comes about contingently and only seldom. Indeed, some things, such as generable and corruptible things, come about necessarily, even though in themselves they are not necessary, but contingent. By contrast, things that are contingent in the second way come about contingently and are generated contingently, and they are not necessary in themselves. Thus both sorts of contingency are in things, since some things are produced contingently through motion and are also contingent in themselves.
But I don't see how it's possible to prove the contingency of things a priori, since one can't prove it through the definition of the subject of contingency, namely being, since there is no order2 and therefore it is difficult to find a middle term for such a proof, or through the passions of being, or through a prior passion, because there is no passion of being prior to contingency, since contingent and necessary together are the [most basic] division of being. Nor could one prove contingency by supposing the other disjunctive passion of being, namely necessity, unless one stipulated that they are relative opposites in the way that cause and caused are—which is false. For it does not follow that if the nobler disjunct exists in the universe, the less noble disjunct does also. Now the converse inference does hold, but then you don't have an a priori argument.
Even the Philosopher,3 who affirms that there is contingency in things, did not prove this a priori, but a posteriori, on the grounds that if there is no contingency, there is no point in making any effort or deliberating. For it is at least as well-known to everyone, if not in fact better-known, that there is contingency in things as that there is a point in deliberating and making an effort.
So it can be proved a posteriori, on the grounds that otherwise there would be no need for virtues or precepts, merits or rewards, punishments or honors: in short, all civic order and all human interaction would be destroyed. And to those who deny contingency one should respond with torments and fire and suchlike; they should be beaten until they acknowledge that it is possible for them not to be tormented and thus affirm that they are tormented contingently and not necessarily—much as Avicenna4 proposed doing to those who deny the first principle. They should be whipped, he said, until they knew that being tortured and not being tortured, being burned and not being burned, are not the same.
So given that one cannot prove a priori that there is contingency, much less can one prove that some particular event takes place contingently.
2 That is, contingency does not characterize being in virtue of some further feature of being that is intermediate between being and contingency (and therefore explains why contingent being is contingent); rather, contingency characterizes being immediately.
3 De interpretatione 9 (18b31–19a5).
4 Metaph. I c. 8.