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Arguing Successfully about God: A Review Essay of Graham Oppy’s Arguing about Gods

William Lane Craig

Used by permission of Philosophia Christi 10 (2008): 435-42.


Graham Oppy's Arguing about Gods is a wide-ranging and penetrating critique of the arguments of natural theology. Essential to Oppy's project of showing that there are no successful theistic arguments is his account of success in argumentation. Oppy's account not only sets the bar unrealistically high but also appears to be self-defeating, since Oppy fails to provide a successful argument for the truth of his account. Nonetheless, natural theologians cannot afford to ignore Oppy's criticisms of their theistic arguments.

Already reeling from Howard Sobel's hard left hand in Logic and Theism, natural theology is now staggered by Graham Oppy's smashing right in Arguing about Gods. Not that Oppy would dispute the truth of theism or the rationality of theistic belief—his aims are more modest. Although he is not a theist, Oppy repeatedly affirms the rationality of theistic belief, as well as non-theistic beliefs. He thinks that theists can and do have reasons which make it rational for them to believe that God exists. Those reasons may take the form of the various theistic arguments. But while those arguments may render the theist's belief in God rational, still they are not successful arguments because they ought not to be considered convincing by all reasonable non-theists. An analogous claim can, in Oppy's view, be made about anti-theistic arguments as well.

"The main thesis that I wish to defend in the present book," writes Oppy, "is that there are no successful arguments about the existence of orthodoxy conceived monotheistic gods—that is, no arguments that ought to persuade those who have reasonable views about the existence of orthodoxly conceived monotheistic gods to change their minds" (xv). A highly competent and impressively widely-read philosopher, Oppy criticizes in detail both cosmological and teleological arguments, updates his earlier critique of ontological arguments, incisively criticizes Pascal's Wager, surveys briefly a grab bag of arguments from religious experience, morality, miracles, and so forth, and discusses various versions of the problem of evil.

Underlying Oppy's main thesis lies an account of rational argumentation and rational belief revision which is critically important for understanding Oppy's project. As his emphasis of the world "successful" signals, Oppy espouses an account of argumentation that includes a specific criterion for determining what counts as a successful argument. Unfortunately, Oppy is uncharacteristically sloppy in his characterization of what constitutes a "good" or "successful" argument. Here is what he has to say on the first page of chapter 1 "Preliminary Considerations":

When should we say that an argument for a given conclusion is a successful argument? I defend the view that, in circumstances in which it is well known that there has been perennial controversy about a given claim, a successful argument on behalf of that claim has to be one that ought to persuade all of those who have hitherto failed to accept that claim to change their minds (1).

Since theism is undeniably a claim about which there has been perennial controversy, it follows that a successful theistic argument will be one that ought to persuade all atheists, agnostics, and innocents to change their minds.

Before we dismiss this standard of success as outrageously high, we should realize that Oppy later qualifies this criterion such that the persons who ought to be persuaded by the argument have, as mentioned above, "reasonable views" about the subject or are reasonable people. So, according to Oppy's account, a successful argument in general, and a theistic argument in particular, is one which ought to persuade all reasonable people who have reasonable views about the matter. So if we find that certain persons have not been persuaded by our argument, we have two options: we can conclude either that the people in question are not rational or else that our argument is a failure (13-14). Oppy recognizes that this account "sets the bar very high" (1), but he thinks there are good reasons for preferring it.

This understanding of what constitutes a successful argument colors Oppy's treatment of theistic arguments. Since he wants to show that all such arguments are failures, he repeatedly responds to the arguments by claiming that this or that premise in the argument can be denied by a rational person. This modus operandi leads him to hurl almost every conceivable objection at the arguments he discusses, for implausible or even clearly false alternatives to the premises of a theistic argument may be not be irrational to believe. So, in his discussion of the argument from miracles, we find Oppy objecting,

even if it were conceded that the parting of the Red Sea occurred, it is not clear that the parting of the Red Sea demands a supernatural explanation; and, more important, even if the parting of the Red Sea does demand a supernatural explanation, it is not clear that the best supernatural explanation is to suppose that it is the result of the actions of an orthodoxly conceived monotheistic god . . . . if you are not antecedently convinced that there is an orthodoxly conceived monotheistic god, then it is much less clear that you are obliged to suppose that the best supernatural explanation of the parting of the Red Sea is that it is the result of the actions of an orthodoxly conceived monotheistic god. It isn't hard to dream up alternative supernatural explanations that those who are not antecedently convinced of the existence of an orthodoxly conceived monotheistic god may well find no less plausible . . . (377).

Expressions like "it is not clear," "does not demand," "is not obliged to suppose," "not hard to dream up alternative explanations," proliferate throughout Oppy's book. As a result, many of his objections take on the appearance of mere cavils.

For example, in his handling of the causal principle "Everything that begins to exist has cause"—a religiously neutral metaphysical principle which is nearly universally accepted and, to my mind, obviously true—Oppy insists that "before we can assent to the claim that there is an efficient cause for the coming into existence of any thing, we need to be told a lot more about the analysis of efficient causation" (152), and he proceeds to list no less than eight classes of nettlesome questions concerning the nature of causation that need to be answered in order to assess the worth of cosmological arguments (170-171). It is easy to multiply questions and to assume the sceptical stance when the premises of a successful argument must be nothing less than rationally compelling.

So in one sense Oppy has made his project much too easy, for a good many natural theologians today would be quite willing to concede that the arguments they champion are not composed exclusively of premises which can be denied only on pain of irrationality. Even if their arguments are not rationally compelling, still, they would insist, the arguments should not be adjudged to be failures. So when Oppy remarks that "the main thesis that I wish to defend is denied by many contemporary philosophers" (xv), we must ask what it is about that thesis that many philosophers will dispute. Not, as I say, the claim that there are no theistic (or anti-theistic) arguments that meet Oppy's high standard for success; rather their bone to pick will be with Oppy's standard itself. When many contemporary philosophers maintain that there are successful arguments about the existence of God, it is because they reject Oppy's account of rational argument and belief revision.

It therefore becomes crucial that we inquire as to the grounds Oppy offers for his account. Reading and re-reading the relevant section of his book (1.2), I was struck that Oppy offers no argument at all in support of his view. He sketches an account of what he takes a successful argument to be, but no argument in favor of that account. In fact, late in the book, we find the admission, "I have assumed that all reasonable parties to the dispute about the existence of orthodoxly conceived monotheistic gods will agree with me about the way in which reason, argument, and dialectic ought to be understood" (425). Such an assumption is obviously false.

In fact Oppy's position seems to be self-defeating. For we find ourselves in circumstances in which it is well-known that there has been perennial controversy about what constitutes a successful argument. Therefore, by Oppy's own account, a successful argument on behalf of his account of successful arguments must be one that ought to persuade all reasonable people with reasonable views on the subject who have hitherto failed to accept that account to change their minds. But Oppy offers nothing of the sort. Therefore, although it may be reasonable for Oppy to accept his account, the rest of us who disagree with it have not been given any reason, much less rationally compelling reasons, to embrace it. Indeed, it is hard to imagine how Oppy could come up with such a rationally compelling argument for adopting his standard of success in argumentation. But then his argument for the main thesis of his book must, by his own lights, be deemed a failure. For he has not shown that those of us who think that there are successful theistic arguments are, as he claims, not reasonable persons (426).

There are, moreover, reasons to call into question the account that Oppy gives of rational argumentation. Leave aside Oppy's assumption that "the proper function of arguments is to bring about reasonable belief revision" (10)—though he himself later admits that mathematical proofs, for example, do not serve this function (14). His claim that theistic arguments have no other function than belief revision is, I think, patently false, since such arguments also serve to confirm the faith of believers and to guide theologians in the formulation of a systematic theology. But leave that aside.

In answer to the question, "what shall we take to be the characteristics of a good (or successful) argument?," Oppy offers what he deems the "easy" answer: "a good argument is one that succeeds—or perhaps would or ought to succeed—in bringing about reasonable belief revision in reasonable targets" (10). This characterization allows degrees of success: the most successful argument would or ought to persuade any reasonable person to accept its conclusion, while less successful arguments would or ought to persuade some reasonable persons to accept their conclusions (Ibid.). Oppy proceeds to raise certain difficulties with the easy answer, but I cannot see any reason given for thinking that success is not a degreed or person-relative property. What one looks for in vain is any reason from Oppy to think that an argument is a failure unless it would or ought to persuade all reasonable persons to accept its conclusion.

In discussing the acceptability of an argument's premises, Oppy asserts,

If a reasonable person need not accept all of the premises of an argument, then that argument does not give all reasonable people a reason to accept its conclusion. If a reasonable person ought not to accept all of the premises of an argument, then that argument cannot give any reasonable people a reason to accept its conclusion (11).

These are dark sayings. The first seems to assert that a person who is not rationally compelled to accept every premise of an argument has not been given any reason whatsoever to accept the conclusion, which assertion seems obviously false. The second is dreadfully ambiguous (is the person not obliged to accept every premise or is he obliged to withhold acceptance of some premise?), but in any case the assertion seems once more clearly false, not only for the foregoing reason but also because what is the case for one reasonable person need not be the case for all.

Oppy then considers two rational agents A and B and supposes that A wants to persuade B to accept the proposition that p (12). Now B has either considered p or not. Suppose not. If A offers B a sound argument for p based on premises B accepts, that "will be an argument that succeeds in giving B a reason to accept the conclusion that p" and leads to rational revision of B's beliefs (12). So why is this not a successful argument? Oppy recognizes as "platitudinous" that there are propositions which reasonable people can disagree on and that there is no unique set of "priors" that every reasonable person brings to an argumentative situation (7-8). So if A is perfectly rational in believing his priors and premises and B rationally accepts them as well, how can A's argument be deemed a failure in bringing about rational belief revision in B? Oppy's view requires that to be a success, A's argument must persuade any rational person with reasonable views of the subject to accept p, so that despite his success with B, A's argument may be a failure. But Oppy gives no argument for thinking this to be the correct way to appraise arguments.

Suppose that B has considered p but rejects it or is agnostic about it. Suppose A again offers B a sound argument for p based on premises B accepts. So long as B is more firmly committed to the premises than to not-p (or beliefs supporting not-p or agnosticism), A's argument will again lead to rational belief revision on B's part. Yet on Oppy's account we must say that A's argument may well be a failure, a conclusion which surely requires some argument.

Finally, suppose that A's argument contains premises that B rejects. Oppy asserts, "any argument that . . . proceeds from premises that B does not accept—will not be an argument that succeeds in giving B a reason to accept the conclusion that p. To repeat this last point: an argument that takes as premises propositions that those to whom the argument is directed do not accept is a failure" (12). Even on Oppy's own account this conclusion overreaches. For the premises may be propositions which B, as a reasonable person, ought to accept, even though he does not. Thus, arguments based on premises which one's interlocutor rejects may well be successful, on Oppy's account, even though they do not lead to rational belief revision (130-1). Though an otherwise reasonable chap, B is being unreasonable in resisting p. And once more, all this still begs the question why, in order to be successful, the premises of A's argument must be rationally compelling for B. Why cannot A have given good reasons to B for accepting p even though B is rational in resisting A's premises?

It seems to me, therefore, that Oppy's project fails at a fundamental level. His own account of successful argumentation requires that if he is to convince those of us who think there are successful theistic arguments to change our minds, then he must provide a rationally compelling argument for his account of successful argumentation—which he has not even attempted to do.

But Oppy's project has another fundamental failing as well. Suppose the natural theologian accepts Oppy's account of success in argumentation and thinks himself to have successful theistic arguments. Seeing that otherwise reasonable people disagree with him about his argument's worth, he concludes that their rejection of his arguments is unreasonable. So he believes. But he does not argue for the irrationality of those unmoved by his arguments; he does not try to persuade others that such persons are unreasonable. Rather he just sticks to arguing for the truth of his premises, in hopes that reasonable people will accept them. Suppose, for example, the natural theologian thinks that the ontological argument is rationally compelling, but that he cannot prove that it is. This is a coherent position. It is not to admit that the ontological argument is not, after all, rationally compelling, for he is convinced that it is. He is convinced that all perfectly rational persons would or ought to accept its premises and conclusion. But he cannot prove that this is the case. It will be futile for Oppy simply to respond that it is reasonable to withhold acceptance of its key premise, for our natural theologian will disagree with this assessment. Since there are no perfectly rational persons about to gainsay him, the natural theologian who finds the argument compelling is not refuted by the avowal by others that they do not. What is needed in this case is some defeater of the argument. So, again, Oppy makes it too easy for himself, even given his account of successful argumentation, when he thinks to defeat arguments just by asserting that it is reasonable to withhold belief from the premises of the arguments he discusses.

Lest I give the wrong impression, I hasten to add that although Oppy does raise many cavils in his book, he also provides substantive, challenging objections to the premises of theistic arguments which defenders of those arguments cannot afford to ignore. Space does not permit discussion of these various objections. Many of Oppy's objections to the cosmological and teleological arguments are effectively handled, I think, by Alexander Pruss and Robin Collins respectively. I should like to comment here only on Oppy's handling of the logical problem of evil, for I believe that his critique is predicated on an inadequate grasp of the doctrine of middle knowledge.

Oppy objects that Plantinga's Free Will Defense contains an inconsistency that has not been previously raised (268-272). Logically prior to God's creative decree the counterfactuals of creaturely freedom (CCFs) known to God via His middle knowledge are "then" either part of the truth-making core of the world or not. If they are, then no one ever acts with libertarian freedom. Why?—because "there is no other world with the 'then' same truth-making core in which agents do anything other than what they do in the world in question" (268). We need not pursue the objection further, for it is already clearly wrong-headed. Obviously, there is no possible world in which a person finds himself in circumstances C and it is true that if he were in C he would do action A and the person does not do A. But why does Oppy take this truism to be freedom-negating? The answer hangs on his conception of the "truth-making core" of a world. The truth-making core of a world prior to a time t is the set of propositions true at t which are already fixed by the world prior to t (266, n. 9). In order for an action to be free, the truth-making core of the world must be consistent with the action's being taken or not taken. If there are truths about future contingents, these cannot therefore be part of the world's truth-making core. It is apparent that what Oppy is trying to capture by this notion is what is called temporal or accidental necessity by philosophers engaged in debates over divine foreknowledge and human freedom. The truth-making core of a world at t is all propositions temporally necessary at t.

It is at once evident that to apply this notion to divine middle knowledge of CCFs is maladroit, since the priority involved is not temporal. No one has articulated a modality for logical priority analogous to temporal necessity. Logically prior to the divine decree, these CCFs are true, and yet creatures, should God create them, can act in such a way that, were they to do so, different CCFs would have been true and God's middle knowledge would have been different. Does that imply, as Oppy thinks, that these CCFs cannot therefore constrain God's actions? Of course not, for they are true prior to His decree and so independent of His will. Oppy fails to distinguish between first-person and third-person counterfactuals of freedom (274, n. 17). Only the latter are part of what Thomas Flint calls a person's "world-type" and so beyond one's control. Logically prior to God's creative decree, first-person counterfactuals of divine freedom, unlike CCFs, have no truth value, are not known to God via middle knowledge, and are therefore within His control. His choices are constrained only by the CCFs true at that stage. Contrary to Oppy, the reason Plantinga "misses this objection" (272) is because it is completely misconceived. This section of Oppy's book is so confused (N.B. his unwitting conflation on p. 274 of Plantinga's illustrations of the bribe to Curly and the bribe to one's departmental colleague regarding a letter of recommendation), that his discussion of the Free Will Defense against the logical version of the problem of evil becomes unprofitable.

One stylistic feature of the book deserves mention: Oppy consistently substitutes the phrase "orthodoxly conceived monotheistic god" for "God." This pedantry results in sentences like the following:

If we think about the argument in this way, then it seems to me that the assignment of infinite utility to wagering on an orthodoxly conceived monotheistic god if an orthodoxly conceived monotheistic god exists becomes irrelevant: all that can matter is whether an agent assigns a high enough utility to wagering on an orthodoxly conceived monotheistic god if an orthodoxly conceived monotheistic god exists to bring it about that the expected utility of wagering on an orthodoxly conceived monotheistic god is greater than the expected utility of not wagering on an orthodoxly conceived monotheistic god.

Is the increase in precision in this case really worth the sacrifice of readability?

Oppy's book is not merely recommended but essential reading for anyone interested in natural theology today. No one can pretend to a successful theistic argument unless he has dealt with Oppy's criticisms first.