When the book was first released, Dr. Dolezal dropped me a kind note in order to bring his book to my attention. I was grateful for the suggestion, but at the time I was too busy working on several projects including my most recent book, Taking Rites Seriously: Law, Politics, and the Reasonableness of Faith (Cambridge University Press, 2015). Now that I am working on a book on Thomas Aquinas and Evangelicals--which is probably at least two years away from completion--I wanted to reacquaint myself with some of the issues in philosophical theology that originally drew to me philosophy as a young man. Among those issues is the question of divine simplicity, the doctrine that God is simple. It is a doctrine--embraced as uncontroversial by the Catholic, Orthodox, and Reformed traditions until fairly recently--that maintains that God is not a composite entity. In fact, he is not an entity at all, but the Transcendent Creator and Source of all that is non-divine.
To say that God is simple does not mean that God is stupid or easy to understand. Rather, it means that God is not a creature whose whole requires composition. He is not a composite being with parts. Take, for example, a typical human being. She is material, which means she has physical parts. She also consists of actuality and potentiality. That is, as long as she exists she has the potential to change and actualize some unrealized potential. We know what these unrealized potentials could be because we know the sort of thing she is, a rational animal. So, for example, my niece Riley has the unrealized potential to master the Italian language, a potential not shared by the family cat. When Riley was a fetus, she had even more unrealized potentials. We make these judgments about individual human beings because we know their essence or nature—rational animal—which we could still know even if the individual human being about which we are making our judgment had never existed. So, human beings, as with everything else in the universe, are also composed of essence and existence. But this is not true of God. God, because he is Pure Act, must be identical to his essence, since what is self-existent and eternal cannot not exist. If God were not simple—if he were like us, composite beings—then his existence would depend on causes outside of himself, and thus he would be just another contingent being in the infinite series of per se causes within the universe. But such a series is impossible, even if the universe had always existed.
Despite its impressive pedigree, divine simplicity has come under withering critiques over the past several decades by a variety of Christian thinkers, including Alvin Plantinga, William Lane Craig, and Thomas Morris. In this book, Dr. Dolezal not only responds to these critics, but clarifies the doctrine in replies to some friends of divine simplicity including Jay Wesley Richards and Eleanor Stump.
Although divine simplicity is a de fide dogma of the Catholic Church, it was for generations, as I have already noted, uncontroversially embraced in the Reformed tradition as well. Thus, it should not entirely surprise us that Dr. Dolezal is a Reformed Baptist and not a Catholic. His work is a welcome addition to the growing body of literature--both inside and outside the Catholic Church--that recognizes that modern conceptions of God--even those embraced by our dearest Christian friends--depart from what our predecessors considered essential to a true understanding of the divine.
God Without Parts may be the best defense of divine simplicity, and exposition of Thomas Aquinas' presentation of the doctrine, I have ever read. I highly recommend it.
If you don't have time to read the book, you should at least take a look at a video podcast of Dr. Dolezal being interviewed on the subject: