St. Thomas's Rejection of Ockham's Way Out

I would like to explore briefly St. Thomas's rejection of the "Ockhamistic solution" to the most compelling argument for the conclusion that God does not and cannot have knowledge of singular future contingents--an argument which, if successful, shows that either God lacks comprehensive knowledge of the future or else there are no genuine future contingents. (I will call this the Necessitarian Argument.)

I will argue that (i) St. Thomas deliberately states the Necessitarian Argument in a less than wholly precise form in order to distinguish from one another the various types of necessity that fall under the rubric 'absolute necessity', and that (ii) what at first glance appears to be St. Thomas's rejection of Ockhamism is really not a rejection of Ockhamism at all, but that we must look more carefully at St. Thomas's discussion of the Necessitarian Argument to see where he differs from Ockham.


A. The Necessitarian Argument

We must be wary of how we interpret the Necessitarian Argument as laid out by St. Thomas in Sentences 1.38.1.5, De Veritate 2.12, and Summa Theologiae 1.14.13. First of all, we must reject any interpretation that explicitly locates God's cognitive act within time, since St. Thomas employs the vague cognitive locution est scitum a Deo, which hovers between 'is known by God' and 'was known by God' and can be used in good conscience even by one who (like St. Thomas himself) denies that God's cognitive act is properly located in time. Second, we must be careful not to import accidental necessity (the necessity of the past) into the very structure of the argument, since St. Thomas himself invokes only 'absolute' (vs. 'hypothetical') necessity.

The Necessitarian Argument as St. Thomas states it goes as follows, where the term 'this thing' denotes an entity or state of affairs that will be brought about in our future:

• (1) In every true conditional, if the antecedent is absolutely necessary, then the consequent is absolutely necessary. [premise: principle that absolute necessity is closed under entailment]

• (2) The conditional If it was known by God that this thing is going to be, then this thing is going to be is true. [premise]

• (3) The antecedent It was known by God that this thing is going to be is absolutely necessary. [premise]

• (4) Therefore, the consequent This thing is going to be is absolutely necessary. [from (1), (2), and (3)]

In order to reach the deterministic conclusion we need a principle that takes us from the absolute necessity of a future-tense proposition to its unpreventability:

• (5) If a future-tense proposition Such-and-such is going to be is for any reason absolutely necessary, then there is nothing that any (free or natural) agent can do to prevent the corresponding present-tense proposition Such-and-such is from being true at the relevant future time.

And this in turn yields the conclusion:

• Therefore, there is nothing that any (free or natural) agent can do to prevent This thing is from being true at the relevant future time. [from (4) and (5)]

The first thing to note is that St. Thomas himself accepts everything up to and including step (4). For in each of the three relevant texts he first rejects various proposals aimed at showing that (3) is false and then goes on to reject a response according to which (1) is false. What's more, in all three texts he unambiguously affirms that the relevant conditional's antecedent and consequent are both absolutely necessary.

To be sure, St. Thomas repudiates the idea that God's cognitive act is itself located at some moment in time. However, this constitutes a rejection not of any of the premises of the above argument, but only of one possible ground for the truth of the premise that the antecedent It was known by God that this thing is going to be is absolutely necessary. My contention is that if one were to import that ground, viz., accidental necessity, into the very structure of the argument, then he would thereby obscure St. Thomas's acceptance of this antecedent's absolute necessity and thus render St. Thomas's discussion of the argument needlessly recondite.

Someone might retort that though the term 'accidental necessity' does not occur in the argument as presented in any of our three texts, St. Thomas has the relevant modal concept at his disposal and indeed uses it in other places. Further, in all three texts the confirmation that follows the Necessitarian Argument tries to establish the absolute necessity of the antecedent in question by noting that it is "something said about the past". But if this is so, then what's my complaint? Wouldn't an intepretation that imported accidental necessity into premise (3) render the argument more precise?

The problem is that such a reconstruction would give us a distorted image of the dialectical context within which St. Thomas is operating. St. Thomas's own reply to the Necessitarian Argument as set out above is to reject (5). His claim in effect is that among all the possible grounds for a proposition's being absolutely necessary, only some will get us to the conclusion of the Necessitarian Argument. One contemporary commentator has remarked in passing that absolute necessity is "a grab bag of modal notions that today we like to keep distinct." What I am urging is that this is exactly the point St. Thomas is making in his own reply to the Necessitarian Argument. He agrees that both the antecedent and the consequent of the conditional If it was known by God that this thing is going to be, then this thing is going to be are absolutely necessary. What he denies is that the two grounds in this case for absolute necessity preclude the causal contingency of what God knows. (For the record, these two grounds are (i) the immutability of the eternal and (ii) the presentness outside its causes that a future contingent has qua seen by God in eternity). Hence, it is precisely the vagueness of the notion of absolute necessity that St. Thomas wishes to underscore and to exploit.

By contrast, on the reconstruction of the argument that I am impugning, St. Thomas seems to be denying not only the absolute necessity of the relevant antecedent, but its truth as well. For on that reconstruction the antecedent is (equivalent to) It was known by God at some time in the past that this thing is going to be--a proposition that St. Thomas clearly denies. But then the puzzles arise: If St. Thomas deems the antecedent false, why does he spend so much time refuting the claim that it is not absolutely necessary? And why does he insist that both the antecedent and the consequent are in fact absolutely necessary?

The plain truth of the matter is that the vagueness inherent in the Necessitarian Argument as set out above plays a crucial role in St. Thomas's refutation of the competing replies to the argument and in his delineation of his own alternative reply. Ironically, this is obscured by the more precise rendering of the argument.


B. Contra Ockhamism?

St. Thomas rejects three distinct proposals aimed at undermining the premise that the proposition It was known by God that this thing is going to be is absolutely necessary. Since Ockham's way out impugns this very same premise, it is reasonable to ask whether what St. Thomas says here can plausibly be construed as a critique of Ockhamism.

However, at this point we must resist the temptation to look only at St. Thomas's treatment of the first of the three proposals, which looks like Ockham's on the surface. I will argue instead that it is only in the treatment of the third proposal that we get some inkling of how St. Thomas would criticize Ockham's way out. I will now corroborate this claim by briefly examining each of the three proposals.

1. Proposal One: The first proposal, due to St. Albert the Great, goes as follows: "Even though the proposition It was known by God that this thing is going to be is a true past-tense proposition, it expresses a relation to what is future and for this reason serves as a counterexample to the supposedly general principle that every true past-tense proposition is absolutely necessary. To see this more clearly, call to mind Aristotle's distinction between two senses of the future-tense locution 'is going to be': (i) a sense in which it expresses merely a present causal tendency or inclination toward a future thing, a thing that exists now only 'in its causes', and (ii) a sense in which it expresses a future thing insofar as that thing will have come to exist in actuality 'outside its causes'. Obviously, from the fact that something was going to be in the first sense it does not follow that it was or is going to be in the second sense. For interfering causes often prevent present causal tendencies from being actualized. Likewise, from the fact that something was known by God as going to be in the first sense, it does not follow that it was or is going to be in the second sense. Hence, God's past knowledge of our future is not itself absolutely necessary."

However, St. Thomas is clearly correct in countering that Aristotle's distinction has no bearing on whether the proposition It was known by God that this thing is going to be is absolutely necessary. For, as he points out, even if we take the locution 'is going to be' in the first sense, as this first proposal is ostensibly urging us to do, it is still an absolutely necessary fact about the past that a certain causal tendency once existed; and, assuming for the moment that God's cognitive act is located in the temporal past, it is likewise an absolutely necessary fact about the past that this tendency was once known by God. So Aristotle's distinction does not of itself undercut the principle that every true past-tense proposition is absolutely necessary.

Further, Aristotle's distinction plays no role at all in Ockham's own reply to the Necessitarian Argument. In fact, in his explicit treatment of divine foreknowledge Ockham lays down principles governing the future tense that are incompatible with the first sense of 'going to be'. The most important of these are (i) the principle that if a proposition to the effect that something is going to be at a future time t is true now, then it has always been true, and (ii) the principle that such a proposition cannot change from being true to being false, or from being false to being true, at any time before t. By contrast, a proposition to the effect that such-and-such is going to be at t, where 'going to be' is taken in the first sense, may vacillate between truth and falsity any number of times before t, since the world's causal tendencies may keep shifting back and forth; indeed, it was this very feature that the first proposal was trying to exploit. Ockham, on the other hand, is clearly taking the locution 'going to be' in the second sense rather than the first sense. And what he claims is this: Given that the proposition It was known by God that this thing is going to be is now true, it follows that (i) it has always been true, that (ii) it cannot change from being true to being false before the relevant future time, and yet that (iii) it is accidentally contingent, i.e., such that it is even now able never to have been true. I conclude that, despite appearances and despite (I confess) what I myself had always assumed, the first proposal considered by St. Thomas is not an Ockhamistic proposal after all.

2. Proposal Two: The second proposal, which St. Thomas attributes to Peter Lombard and discusses only in the Sentences commentary, denies the absolute necessity of the proposition It was known by God that this thing is going to be on the grounds that God's cognitive act is eternal and is hence not located in the temporal past.

St. Thomas's reply is that even though the divine cognitive act is not located in the past, it is nonetheless absolutely necessary because "it has the necessity of immutability"--a sort of necessity which is the analogue, within the order of eternity, of the necessity of the past within the order of temporal succession. So even though God's knowing a given future thing is metaphysically contingent, nonetheless, once this knowledge is posited as actual in eternity, it is no longer able not to exist (or to have existed) within eternity. Consequently, there is nothing wrong with the assumption that the proposition It was known by God that this thing is going to be is true, as long as the locution 'was known by God' (est scitum a Deo) is taken to signify God's eternal cognitive act; and if this proposition is indeed true, then it is also absolutely necessary because of the immutability of the eternal.

I will not tarry over the second proposal, since it is obviously not Ockhamistic. Quite the contrary, Ockham's strategy is to focus not on God's cognitive act itself but instead on the objects of that cognitive act. And this brings us directly to the third proposal.

3. Proposal Three: The third proposal, due to St. Bonaventure, is this: "The proposition It was known by God that this thing is going to be contains two distinct elements, viz., (i) the principal clause, It was known by God that ..., which is admittedly necessary because it signifies God's eternal and hence immutable cognitive act, and (ii) the object of that act, the proposition This thing is going to be, which is contingent. But in order for the proposition as a whole to be absolutely necessary, each of these elements must itself be absolutely necessary. Since one of them is contingent, the proposition as a whole is absolutely contingent."

This proposal is more akin to Ockham's than the first two, since it zeroes in on the modal status of the object of God's cognitive act. Indeed, Ockham's view is precisely that even though the divine cognitive act remains intrinsically immutable, its objects change over time, with the (alleged) result that propositions ascribing knowledge to God derive their modal status from the modal status of the propositional objects of that knowledge.

St. Thomas's reply to this proposal parallels one of the standard objections to Ockhamism found in the contemporary literature; he claims, in short, that the modal status of the proposition It was known to God that this thing is going to be is wholly a function not of the modal status of the proposition that is posited "materially" as the object of God's knowledge, but instead of the modal status of the principal clause. "Thus," he concludes, "even if that which is posited materially is contingent, this does not prevent the antecedent in question from being necessary."

Interestingly, this criticism of Ockhamism was accepted by Molina, who responded to the Necessitarian Argument by denying (1), the principle that absolute necessity is closed under entailment. St. Thomas, by contrast, explicitly rejects this Molinist way out and argues instead that the sort of absolute necessity that is transmitted to the consequent in this case is benign and does not conflict with the causal contingency of what God knows.

I conclude that it is only St. Thomas's reply to the third proposal that gives us a glimpse of the general strategy he would use in countering Ockhamism. However, a full-fledged Thomistic reply to Ockhamism must first set out clearly the opposition between the Thomistic and Ockhamistic accounts of how a semantics for future-tense propositions should best embody a correspondence theory of truth, and must then argue for the superiority of the Thomistic account over its Ockhamistic counterpart.