Why Do You Need to Understand the Doctrine of Divine Simplicity?

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.

  • sean

    I’d agree with that doctrine. One cannot assert a fantastically complex god as an explanation for the simple. Well, one could, but it does open that line of inquiry of why does a more complex god get to exist for free if our existence, which is less complex, is so complex an intelligence is required to create it.

    The one thing I don’t understand is how you get from the idea of a simple explanation is required to the idea that something non-material (not composed of parts) can effect (cause) the material.

  • Non-material does not equal no parts. Something can be immaterial and still have metaphysical parts.

    For example, the human soul is immaterial but it is composed of both potentiality and actuality (see my blog post on these metaphysical principles), and thus the human soul is not simple.

    Beyond this important distinction, I don’t see any problem with the immaterial interacting with the material. We see this happening every day when the human mind interacts with the human body. We may not know how exactly this works, but it clearly does.

    Remember that for classical theists, mind is more fundamental to reality than matter. Matter comes from mind, not the other way around.

  • sean

    Fair enough. I’ll agree that within your Christianity it’s the rational position to hold.

  • Patrick

    Are you ever going to blog about the Trinity and divine simplicity? It is hard enough already to fully grasp that God has no parts whatsoever but to fit it in with Him being a Trinity makes it seem, incoherent. Would love to learn more.