Times Literary Supplement, No. 5444 (August 3, 2007): 26. Zero-horrors game Trenton Merricks Peter van Inwagen The Problem of Evil 183 pp. Oxford: Clarendon Press. £ 19.99. 0 19 924560 6 A "proof" is an argument that just about any intellectually honest person would find convincing, unless that person were irrational or stupid or otherwise cognitively defective. Peter van Inwagen, a leading metaphysician and philosopher of religion, considers whether there is a proof for the non-existence of God that starts with instances of evil, such as pain and suffering. Van Inwagen claims that, so far, there have been no proofs in philosophy, at least not of major philosophical theses. Though initially jarring, perhaps this claim should not be surprising. After all, any argument-including any argument aspiring to be a proof- must begin somewhere. It must have premises. And if its conclusion is striking enough, there will almost certainly be some smart people of good will who will find denying one of that argument's premises, even if that denial is itself striking, more reasonable than accepting its conclusion. Given philosophy's track record, van Inwagen doubts that there will be any argument with the conclusion 'God does not exist' that virtually every intellectually honest (etc.) person would find convincing. Indeed, he thinks philosophy's track record 2 suggests that no argument against God's existence would convince even virtually every intellectually honest agnostic, never mind the intellectually honest who approach such an argument believing firmly in God. But there is a first time for everything. So he takes a careful look at arguments that purport to prove, from evil, that God does not exist. Van Inwagen's central objections to these arguments turn on the idea that free will is a great good, even though free creatures might choose to cause pain and suffering and other evils. Of course, this idea is familiar. Van Inwagen's contribution is not this idea itself, but rather the ways in which he motivates it, responds to objections, and brings new clarity to various points. Along the way, he makes many interesting and novel moves. For example, he asks us to suppose the following for the sake of argument: a man commits assault; sending that man to prison brings about the good of deterring further assaults; this good could be had by sending the man to prison for ten years; this same good could be had by sending him to prison for ten years minus one day; in general, sending him to prison for n-1 days deters assault no less than does sending him to prison for n days; finally, each day spent in prison is an evil. Given these suppositions, sending the man to prison for ten years brings about no good not also brought about by sending him to prison for ten years minus one day. So it seems that we ought to send him to prison for ten years minus one day, rather than for the full ten years. At least, this is implied by the following plausible moral principle: if one is able to prevent an evil, one should not allow that evil, unless allowing it thereby brings about a greater good (or prevents a greater evil). 3 But the very same reasoning then tells us that, rather than send the man to prison for ten years minus one day, we ought to send him to prison for ten years minus two days. It then tells us that we ought to send him to prison for ten years minus three days. Eventually, this sort of reasoning will tell us that we should send the man to prison for zero days, that is, not send him to prison at all. Something has gone wrong. Van Inwagen thinks the culprit is the plausible moral principle itself. He takes this reasoning to show that that principle leads to a false result, and so is itself false. Van Inwagen also argues that, given certain conditions, it is good that the world is risky, even to the extent that sometimes this or that 'horror' occurs, such as a brutal murder or a cancerous tumor. And he thinks that there are certain horrors that help to make the world risky, but serve no other good purpose. He adds that no particular such horror is necessary for a risky world. Now consider one such horror. God could have left everything pretty much just as it is, except for preventing that horror, and nothing good would have been lost, not even the riskiness of the world. The most natural reaction is that God should have prevented that horror. But if the aforementioned plausible moral principle is false, this reaction is not obviously right. Moreover, van Inwagen thinks that those who endorse this reaction must add that God should prevent every horror that is, first, not absolutely necessary for the world's riskiness and, second, whose only good is contributing to that riskiness. This addition presupposes, says van Inwagen, that there is some minimum number of horrors necessary for that riskiness. He rejects this presupposition, saying: 'For any n, if the existence of at most n horrors is consistent with God's plan, the existence of at most n-1 horrors will be equally consistent with God's plan' (p. 106). 4 I think that van Inwagen should not reject this presupposition. For suppose God prevents one horror, whose only good would have been contributing to the world's riskiness. That riskiness remains, since van Inwagen thinks that 'God's plan' does not turn on any single horror. Suppose God prevents another such horror. The riskiness remains. You see where this is going. Eventually, we get the result that zero horrors are necessary for riskiness. Something has gone wrong. I conclude that the culprit is van Inwagen's thesis that there is no minimum number of horrors necessary for riskiness. Van Inwagen will reject my reasoning, which is meant to show that his 'no minimum number' principle is false. But that reasoning mimics his own argument against the above plausible moral principle. So either his argument against the plausible moral principle fails or his 'no minimum number' principle is false. Something has to give. Even these critical remarks point to the virtues of van Inwagen's book. For example, consider van Inwagen's idea that there is no minimum number of horrors necessary to achieve a particular good. This idea, van Inwagen argues, implies that God, even if all-powerful and morally perfect, can achieve that good only by arbitrarily 'drawing a line' between the horrors allowed and the horrors prevented. Van Inwagen's conclusion that such arbitrariness is part and parcel of providence is not only bold and provocative, but is also made more believable than one would have expected. The same goes for van Inwagen's attack on the plausible moral principle. And for his idea that riskiness is a good. And for much else in this fine book. Trenton Merricks is Professor of Philosophy at the University of Virginia and the author of Objects and Persons and Truth and Ontology.