This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.


Dear Dr. Craig,

You have often said that the problem of evil is the best argument for atheism, but I actually disagree. I think that the incoherence argument(s) is the best. What responses have you given to these arguments. There is a whole book published by Prometheus books about the various incoherence arguments against God's existence, and the number is huge. It's called 'The Impossibility of God', edited by Michael Martin of Boston University.

Take this Modus Tollens argument:

1) God is all-powerful

2) But God cannot do certain things like evil and he can't interfere with somebody's free will.

3) Therefore, God does not exist.

This is just one of a whole array of seemingly impossible arguments to refute. What say you?

To me, this seems to be a serious problem for theism and I'm even thinking of giving up belief in God because of it so I would appreciate your help. If nothing else, please let me know of some books that answer these arguments. Thank you very much.


United States

Dr. William Lane Craig’s Response

Dr. William Lane CraigYour question is near and dear to my heart, Anthony, because my entire philosophical career has been an exploration of the coherence of theism. As a young philosopher fresh out of graduate studies, I had to decide what research project I would embark upon as my area of specialization. Inspired by Anthony Kenny’s little book The God of the Philosophers (1979), I decided to analyze philosophically the various attributes of God with a view toward crafting a coherent concept of God. I discovered a subject matter so vast in its reach, so profound in its depth, and so challenging in its concepts that it soon became obvious to me that such a project would span a lifetime.

So I spent the first seven years studying and writing on the concept of divine omniscience, with a particular focus on the compatibility of divine foreknowledge and human freedom. Then I spent the next eleven years studying and writing on the concept of divine eternity, trying to hammer out God’s relationship to time. Most recently, I have invested the last dozen years studying the concept of divine aseity, focusing on the challenge posed by abstract objects to God’s being the sole ultimate reality, and now I am in the course of writing up the rewarding results of those many years of study.

One of the respects in which contemporary Philosophy of Religion has changed most dramatically since I first began my research programme is precisely with respect to the coherence of theism. During the previous generation (roughly the third quarter of the twentieth century) the concept of God was often regarded as fertile ground for anti-theistic arguments. The difficulty with theism, it was said, was not merely that there are no good arguments for the existence of God, but, more fundamentally, that the notion of God is incoherent.

This anti-theistic strategy backfired, however, as it evoked a prodigious literature devoted to the philosophical analysis of the concept of God, thereby refining and strengthening theistic belief. William J. Wainwright’s Philosophy of Religion: An Annotated Bibliography of Twentieth-Century Writings in English (1978) was a landmark guide to the literature at that time. Although these topics continue to be discussed (witness my own work!), the heat of the battle is largely past. Since the concept of God is underdetermined by the biblical data, philosophers working within the Judaeo-Christian tradition enjoy considerable latitude in formulating a philosophically coherent and biblically faithful doctrine of God. Theists thus found that anti-theistic critiques of certain conceptions of God could actually be quite helpful in framing a more adequate conception. Thus, far from undermining theism, the anti-theistic critiques served mainly to reveal how rich and variegated and challenging is the concept of God. Today the discussion continues primarily as an exploration in philosophical theology, not as an apologetic enterprise.

Anthony Kenny once remarked to me that the Philosophy of Religion is so interesting because, like the hub of a wheel whose spokes radiate outward, it touches every other area of philosophy. My study of God has certainly borne that out. My current work alone has taken me deep into metaphysics, philosophy of mathematics, and philosophy of language. The study of God’s attributes has been a rich and rewarding experience, both intellectually and spiritually.

Two controls tend to guide philosophical theologians’ inquiry into the divine nature: Scripture and Perfect Being theology. For thinkers in the Judaeo-Christian tradition, God's self-revelation in Scripture is obviously paramount in understanding what God is like. But the Bible is not a philosophy book and so is often underdeterminative with respect to God’s attributes. Take divine eternity, for example. The Bible teaches that God is eternal, that is to say, without beginning and end. But there are at least two ways that an entity can be without beginning and end. One way would be to exist from the infinite past into the infinite future, or to have immemorial and everlasting temporal existence. Another way would be to transcend time altogether, that is, to exist but not to exist in time, or to exist timelessly. Now the Bible doesn’t settle that question; if it is to be answered, the answer must come from philosophical and not from biblical theology.

As for Perfect Being theology, Anselm’s conception of God as the greatest conceivable being or most perfect being has guided philosophical speculation on the raw data of Scripture, so that God's biblical attributes are to be conceived in ways that would serve to exalt God's greatness. So when the Scripture affirms that God is, for example, All-Mighty, that should be construed in as great a sense as possible. Here, too, there is room for disagreement. While it is obviously greater to be, say, personal rather than impersonal, morally perfect rather than morally flawed, self-existent rather than contingent, is it greater to be timeless or temporal, simple or composite, mutable or immutable? The answers to those questions are far from obvious and so require supporting arguments.

So when one is confronted with an alleged incoherence in the concept of God, the philosophical theologian usually has two possibilities: either (1) show that the alleged incoherence is merely apparent, not real, or (2) revise one’s concept of God. (Yes, that’s why in my dialogue with Lawrence Krauss I said that theology is just like science in being an on-going enterprise capable of refinement in light of new data.) So, for example, as a result of my study of divine eternity, I came to reject the traditional view that God exists timelessly but rather to hold that He is atemporal only insofar as He exists sans creation—a view that turns out to be quite biblical as well as coherent. Maybe I’m wrong about that (as doubtless many of my colleagues think!). No matter! Biblical theology allows a diversity of views. Present your arguments, and I’ll present mine, and we’ll talk about it.

So I wouldn’t get too worked up, if I were you, about Martin’s book, which is representative of a bygone generation. The argument you share against divine omnipotence is quite hopeless, since the key term “all-powerful” isn’t even defined (not to mention the fact that the argument as it stands is not even a logically valid argument!). If you want to read a brilliant formulation of a coherent doctrine of divine omnipotence see the article “Maximal Power” by two gifted philosophers at the University of Notre Dame, Thomas Flint and Alfred Freddoso. It is one of the finest pieces of Philosophy of Religion that I have ever read. (But be warned: it is very technical!)

Flint and Fredosso’s essay is reprinted in my anthology Philosophy of Religion: a Reader and Guide (Edinburgh: Edinburgh University Press, 2002), along with several other of the top essays on the coherence of theism. More accessible to the lay reader would be my own two chapters in Philosophical Foundations for a Christian Worldview, co-authored with J. P. Moreland (Downer’s Grove, Ill.: Inter-Varsity Press, 2003). Both of these books contain helpful bibliographies which will direct you to the abundant further literature on this topic. No one who knows this literature would think that the arguments for theism’s incoherence are impossible to refute.

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