In his Dialogues Concerning Natural Religion, David Hume alludes to an ancient version of the argument from evil, due to the Greek philosopher Epicurus:
The main defect in this argument lies in the second premise. It is not at all obvious that a perfectly good being must create a world utterly devoid of evil. This might follow if we thought that evil was a positive quality that had to be caused to exist, since it would presumably in that case take a partially evil cause to produce a partially evil effect. However, if we accept the privative theory of evil, that route to premise two is denied us.
An alternative to Epicurus's argument seeks to spell out why a good and omnipotent being would create a flawlessly good world. This alternative is so widely used that it deserves to be called the Standard Argument from Evil.
There are a couple variations on the standard argument that we will encounter later. These variations concern premise 4, 5 and 6. A probabilistic version of the argument would replace premise 4 and 5 with something like this:
4/5p. It is very probable that the best possible world an omnipotent being could actualize would be a world devoid of evil.
There is also a quantitative version of the standard argument, in which the crucial fact is not simply the existence of some evil, but the existence of a certain quantity of evil. In this version, premises 4, 5 and 6 would be replaced by:
4/6q. The best possible world an omnipotent being could actualize would have fewer or lesser evils than the actual world does.
It would also be possible to combine the quantitative and probabilistic variations. However, as we shall see, theistic defenses that are successful against the standard argument tend to be successful against these variations. If the standard argument fails, it is difficult to find convincing reasons to accept 4/5p or 4/6q.
I am going to assume that theists will accept premises 1 and 6. I am assuming that we are dealing with a eutheist who believes in an omnipotent God and who accepts the real existence of evil. Such a theist can respond to the standard argument in either of two ways: the tough-minded approach and the tender-hearted approach. The tough-minded response involves challenging premises 2 or 3. The tender-hearted response instead challenges premises 4 or 5. It is also possible for the theist to employ both responses, challenging 2, 3, 4, and 5.
A tough-minded theist can concede that God would not choose to create evil, either as a means or as an end. Any evil that exists is a foreseeable but unintended consequence or by-product of God's pursuit of innocent ends. However, the tough-minded theist denies that the minimization of evil, or the maximization of good, forms any part of what God intends. He insists that God's goodness is compatible with any conceivable level of evil in creation, even with any conceivable amount of surplus of evil over good. According to the tough-minded theist, God is simply not interested in the question of the total quantity of evil, and this indifference in no way impugns the purity of God's character.
If God is not interested in maximizing the quantity of good contained in the world, what could He be interested in? He might be interested in creating an interesting or a varied world, or in a world in which there is a dramatic and suspenseful conflict between good and evil, with good ultimately triumphing in the end. Or, His motives in creating the world might be inconceivable by us altogether.
In interpreting premises 2 and 3, we must address the question of what is meant by 'a best possible world'. We could define BPW to mean a world in which there is the greatest possible surplus of good over evil. This makes premise 3 true by definition, but it makes premise 2 disputable (at least, according to the tough-minded theist). From this perspective, premise 2 can be challenged in several ways. First, it could be pointed out that premise 2 presupposes something like the ethical theory of utilitarianism: the theory that each of us has, as his paramount moral duty, the obligation of maximizing the surplus of good over evil. It is far from obvious that utilitarianism is true. For example, in the Jewish and Christian traditions, what matters is how we treat specific people we encounter (our "neighbors"), not what effect our actions have on the total quantity of happiness in the world.
Second, even if utilitarianism were true, as a theory of human moral obligation, the principle of analogy gives us reason to doubt that that theory applies to God's choice of which world to create. This divine choice is radically dissimilar to any choice we human beings make. Hence, our confidence in the correctness of utilitarian principles in application to human choices should not carry over to the case of the creation of the cosmos.
Alternatively, we could interpret "best possible world" to mean a world that best fulfills the purposes God has in creation, whatever those are. In this case, it is far from obvious that premise 3 is true. Moreover, it is not clear that even premise 2 is true in this case. It is possible that there are no best possible worlds in this case. It could be that, for every possible world, there are other worlds that are still better. The possible worlds could form an infinitely ascending chain of ever better and better worlds. If this were true (and there is no reason I can think of for supposing it to be false), it would be incoherent to demand that a good God would create no world except a best one. Surely it would make no sense to suppose that God would have to be stymied into inaction by such an embarrassment of riches. A good and reasonable God could choose to create any world that (in some respect) fulfills God's innocent purposes, even though there are infinitely many worlds that fulfill those same purposes to a still higher degree.
Even if utilitarianism were true, and even if it applied to God's act of creation, premise 2 could still be false if there were no world in which the surplus of good over evil is maximized. Perhaps there is some evil in every world, but no level of evil that is the absolute minimum. Worlds might exist that come closer and closer to the ideal of absolute perfection, with none of that actually reaching it. If this were true, we could not reasonably blame God for failing to create a best possible world, since no such things exist.
In summary, the tough-minded theist seems to have quite compelling objections to the standard argument. Does this mean that we can dispose of the problem of evil by relying on the tough-minded response alone? I do not think so, because there are alternatives to the standard argument that cannot be answered in the same way. I will take up one of those alternatives in the next section.
As I mentioned in the last section, the Jewish and Christian traditions hold that the essence of ethics consists in love for particular people, not in the maximizing of an impersonal quantity of happiness or pleasure. This kind of person-directed love is expressed by the Greek word "agape" (ah-gopp-ay) in the New Testament. The argument from evil can be reformulated so that it presupposes an agapeistic instead of a utilitarian ethic.
Some theists (the really tough-minded) would reject premise 1. I will call these the hard-boiled theists. It is hard to see how any form of the argument from evil could touch hard-boiled theism. For many of us, hard-boiled theism comes quite close to dystheism, since, by limiting the scope of God's love, it drives a wedge between ethics and God's character. I will, therefore, consider how a tough-minded but only soft-boiled theist might respond to the agapeistic argument, without challenging premise 1.
Premise 6 seems a weak link. It assumes both : (1) God has no conflicting wants, and (2) God operates under no deontic constraints. A deontic constraint is an ethical prohibition that forbids doing something, even if its consequences would be very desirable. For example, there are deontic constraints that forbid breaking a promise or telling a lie, even when doing so would produce the greatest happiness for those affected.
We could take care of the first assumption (the assumption that God has no conflicting desires) by strengthening premise 1 to read: God's paramount desire is to love everyone. This new premise is considerably less plausible than the original. Even a soft-boiled theist might hesitate to assume that God's desire to love human beings takes precedence over all other values. Nonetheless, even if we accept the strengthened premise 1, we must still deal with the even more difficult matter of deontic constraints.
In order to close this loophole, we would have to add two additional premises:
13. God is bound by no deontic constraints except those He has voluntarily undertaken.
14. If God wants to love x, God would not voluntarily undertake any deontic constraints that would prevent Him from making x eligible for His love.
Premise 13 seems quite reasonable, since God is under no one else's authority. Premise 14 seems plausible, but it is in fact probably false, since it overlooks a very significant possibility. It might be that the very existence of some human beings presupposes the fact that God has already undertaken certain deontic constraints. When God undertakes deontic constraints, when, for example, He enters voluntarily into binding commitments, like promises or vows, this shapes the subsequent course of history in many profound ways. Deontic constraints undertaken by God long ago are inextricably connected with the actual history of humankind. If, as seems plausible, my identity is bound up with my place in human history as it had unfolded at the time of my conception, then my identity presupposes those prior deontic constraints. Had God not undertaken the vows and commitments He has, then human history would have gone very differently, and it would have been logically impossible for me to exist. Someone very much like me might have existed in those very different circumstances, but that person would not be numerically identical to myself. (For a comprehensive treatment of this issue, see Robert M. Adams, "Existence, Evil and Self-Interest", in The Virtue of Faith.)
In order to take this possibility into account, we need to add another proviso to premise 14 and add yet another premise to the argument:
14R. If God wants to love x, God would not voluntarily undertake any deontic constraints that would prevent Him from making x eligible for His love, unless God's so undertaking is a logically necessary condition of x's existence.
15. For no human being x, and for no undertaking by God of a deontic constraint is it the case that that undertaking both prevents God from making x eligible for God's love and is a logically necessary condition of x's existence.
Now, premise 14R seems correct (at least, under the assumption that God's desire to love is His paramount desire). However, premise 15 is plainly false, for the reasons I suggested above. Significant features of the past, up to and including the event of my conception, are logically necessary conditions of my existence. After my conception, things could have gone quite differently without excluding my existence since, once I have come into existence, I can continue to exist under a wide varietyof circumstances. However, any hypothetical change to the conditions of my origin bears directly on the question of whether the resulting person is me or only someone very much like me.
This thesis that the origin of a thing is essential to its numerical identity is defended quite ably by Saul Kripke in his classic, Naming and Necessity. Even if Kripke's theory is incorrect, the agapeistic argument from evil is in trouble unless Kripke's theory (and any relevantly similar theory) is obviously false.
There is another argument that reinforces the point made in the last section. Even if we reject premise 1 of the agapeistic argument, denying that God's paramount desire is to love human beings, we still face a problem raised by Ivan Karamazov, a character in Fyodor Dostoevsky's The Brothers Karamazov. Ivan marshalls several stories of horrific suffering inflicted on innocent children. Ivan argues that no amount of good at the cosmic level could possibly outweigh (to one who loves these children) the horrors besetting them.
As in the agapeistic argument, it is clear that premise 4 needs to be modified by adding two provisos:
4*. ... unless doing so would result in the loss of some greater good, or x's doing so would violate some prior deontic constraint.
If God has entered into binding deontic constraints, commitments that prohibit God's interference in human affairs except in special circumstances, then these constraints can explain why God, despite His love for the children involved, does nothing to prevent the horrors described by Ivan. This answer again raises the further question: why would God enter into such commitments, knowing that they would interfere with His preventing the affliction of His loved ones by horrific evils?
As I argued in the last section, the answer to this latter question may lie in the presuppositions of the existence of the specific human beings involved. If a deontic constraint is a necessary condition of the existence of a particular child, then God's undertaking this constraint cannot be inconsistent with His love for that child. Love presupposes the existence of the beloved, and, therefore, nothing required by that existence can be incompatible with a love relationship.
Are there cases (cases involving horrific evils, such as those put forward by Ivan Karamazov) in which love for a person requires one to prevent that person's existence? Could there be cases in which my love for X demands that I act so as to prevent X's coming into existence? I would argue that the answer to these questions must be, No. As I suggested above, love for X must always be compatible with any condition necessary for X's existence. This truth is expressed by the following principle, the PEPL:
Here is a simple argument for PEPL:
In summary, both the standard arguments and the agapeistic arguments from evil fail. In demonstrating this failure, it was not necessary to bring in the role of free will or other limitations on God's omnipotence. Nonetheless, I believe that there are relevant limitations to God's omnipotence, that provide us with independent grounds for rejecting the arguments from evil.