Post Author: Bill Pratt 

One of my favorite writers these days is Edward Feser. He has a unique way of explaining the most complex concepts about theology and philosophy in ways that laypeople can understand. I was reading a blog post he wrote that explains why the doctrine of divine simplicity is so important.

Feser begins:

At the core of classical theism is the notion of divine simplicity — the idea that God is non-composite or without parts.  This is a doctrine having its philosophical roots in Plato and Aristotle and defended by pagan, Jewish, Christian, and Muslim thinkers as diverse as Philo of Alexandria, Irenaeus, Clement of Alexandria, Athanasius, Plotinus, Augustine, Boethius, Anselm, Maimonides, Avicenna, Averroes, Aquinas, and Scotus.  The doctrine is the de fide teaching of the Catholic Church and is endorsed by many Protestant theologians.  The point of all this name-dropping is to emphasize how absolutely central the doctrine of divine simplicity is to the mainstream Western tradition in philosophical theology.

Feser is pointing out that divine simplicity, the idea that God is not composed of parts, has a deep philosophical history among the greatest thinkers of the past 2,500 years. So why is it so important that God doesn’t have parts, that he is simple?

The reason is that for the classical theist, whatever else we mean by “God,” we certainly mean by that label to name the ultimate source, cause, or explanation of things.  Properly to understand classical theism, the hostile atheist reader might even find it useful to put the word “God” out of his mind for the moment — given all the irrelevant associations the word might lead him to read into the present discussion — and just think instead of “the ultimate source of things.”  The classical theist maintains that whatever is in any way composed of parts cannot be the ultimate source of things.  For wherever we have a composite thing, a thing made up of parts, we have something that requires a cause of its own, a cause which accounts for how the parts get together.

Feser backs this point up from our everyday observations of the world:

This is obviously true of the ordinary things of our experience.  For example, a given chair exists only because there is something (a carpenter, or a machine) that assembled the legs, seat, etc. into a chair.  And the chair continues to exist only insofar as certain combining factors — such as the tackiness of glue or friction between screw threads — continue to operate.  The point applies also to things whose composition is less crudely mechanical.  A water molecule depends for its existence on the oxygen and hydrogen atoms that make it up together with the principles of covalent bonding.

So why must God be simple? Anything composed of parts must have had a composer, but we are looking for the being that has no composer, that is uncomposed. So the ultimate source, cause, or explanation of things cannot be composed by a composer.

Any doctrine of God which denies his simplicity, then, will fall prey to the Dawkins question, “Who designed the Designer?” A simple God needs no designer, but a God composed of parts does.