The Philosophical Attraction to a Simple God
Classical theism claims that God is absolutely ontologically simple. This means that in God, there are no distinctions that amount to real ontological composition. Examples of composition include not just physical parts but also metaphysical parts (or constituents) such as substance and attribute, form and matter, and essence and existence. A part, I take it, is any entity within a whole that is in some sense inferior to the whole and from which the whole is "made up." The doctrine of divine simplicity often strikes people as weird and irrelevant if not incoherent, particularly since it entails other commitments like divine immutability, impassibility, and eternality. Consequently, it is not infrequently denied among theists these days.
This denial, I think, is a mistake. To see why, it might be useful to consider why the majority of theistic philosophers, up until fairly recently, have affirmed divine simplicity. The motivation, in various ways, comes down to the idea of there having to be some relevant difference between the finite, changing, contingent order and whatever the order is that explains it. I take it that a relevant difference is one that can presumably make a principled explanatory difference.1 Not all differences are relevant when it comes to getting an adequate explanation for something, after all. For example, if we are looking to get an explanation for why there is anything contingent, it does not seem like a relevant difference if something is first in the line of contingent things. Does something coming first by itself remove all relevant contingency-implying features or attributes? What if Michael Jackson was the first contingent thing to exist and, by singing "Beat It," caused all the other contingent things after him? The problem is that Michael Jackson, even if he were the first contingent thing (I understand this is probably unlikely), is not relevantly different from all other contingent things to serve as an adequate explanatory terminus. Michael Jackson still has all the usual contingency-implying features of finiteness, mutability, and presumably, coming into and going out of existence. So just saying Michael Jackson was first doesn’t seem like a relevant difference; it’s not the sort of difference that seems to make the right sort of difference. Or even if his shape or degree of power is different from many other contingent things, mere differences in degree along these dimensions do not seem relevant for the sort of explanatory candidate we’re after, either.
The example is silly by design, but the point is structural. Philosophers have long identified various contingency-implying features. Some of them have already been listed, such as something changing, being finite, or coming into or going out of existence. Another major one—arguably, *the* contingency-implying feature—is compositeness, particularly metaphysical compositeness. Indeed, all other contingency-implying features seem to reduce to this one. Changing things are capable of change because they are metaphysical composites of potency and act, having a dynamic capacity to enter into new modes or states of being (actualize various potentials). Finite things are composite insofar as their form is particularized (limited or pinned down) by matter. Such things are often seen to come into and go out of existence because their essence (potency element) is really distinct from their act of existence (actuality element). For many philosophers, a thing’s contingency is explained by that thing being a metaphysical composite and, as such, not identical to its actuality (since no composite whole is strictly identical to its proper parts; it *has* an actuality element) but dependent for it upon some extrinsic condition or set of conditions.
Moreover, composites are made up of their parts, where the whole exists in potency in relation to its parts existing and coming together just so. Composite wholes (in a significant respect) depend on their parts and thus, as a general rule, do not seem well-suited to be the sort of thing that can stand as truly ontologically independent. Said differently, composite wholes are not the right sort of thing to be fully independently real; rather, they all (as a matter of categorical uniformity) seem to be the sort of thing that must be dependently real, caused to exist by something extrinsic to themselves. Just having a composite thing come first in a line, possess fewer parts than other composite things, or have the greatest power of all composite things—none of these seem like the right sort of difference to make a composite entity the ultimate explanatory terminus. Another thing that doesn’t seem to make much of a difference, ultimately, anyway, is something being necessary. After all, something can be necessary but still have some deeper explanation. What we really want is to find a suitable candidate that would not just be necessary but truly ontologically independent and self-sufficient.
This is why I do not think atheists should find it very persuasive if theists just claim God is a necessary reality and that is why someone should endorse theism. After all, if the view of God under consideration is a composite one (of substance and attribute, essence and existence, or what have you), then God does not seem relevantly different from all the other sorts of things that require some further explanation, to which the atheist can rightfully retort: My initial physical state or entity is a necessary reality, so I will just end explanation there, thank you very much. This is also why I don’t like the worldview comparison debate to be framed so much in terms of theism vs. atheism (or other contenders), though of course I am sometimes guilty of framing it that way myself. Rather, it should be approached as simply trying to discern what sort of reality, if any, could not just be necessary but ontologically independent. When one begins with that objective in mind, I think they are far more likely to get at the truth of things and avoid tribalistic impulses.
So, with that in mind, the only sort of difference that actually seems to make a difference, ultimately, is if we have an entity that just isn’t composite at all, but is absolutely simple: whose nature is purely actual, and whose essence is simply its existence. In other words, where all contingency-implying features are stripped away to the point where it becomes quite inappropriate to ask why this thing exists and not nothing instead. It is this “stripping away” approach to ultimate reality that has caused so many philosophers (from Aristotle to Aquinas) to affirm divine simplicity, revealing what the nature of an ultimate foundation to things must be, as the necessary condition for every non-self-sufficient, contingent reality.
Of course, affirming an absolutely simple God does have some “spooky” implications, if you want to call them that (like immutability, eternality, etc.), which in turn invite a considerable number of further questions. How does a simple and immutable God create a contingent world? How does a simple and immutable God know a contingent world? How—for Christians—does a simple and immutable God incarnate into a contingent world? Oh, and the Trinity. How does that fit? Does it fit? These are important questions, no doubt, and I certainly do not claim they are easy to answer. I do, however, claim that there are good answers to them and that such questions are useful in building out the other theoretical commitments within the classical theistic worldview.
For a more rigorous development of this line of thought, see my book The Best Argument for God.
Here’s a guitar solo.
Joshua Rasmussen makes use of the notion of a relevant difference in his argument from limits for God as purely actual and self-sufficient, lacking all arbitrary limits. See his book How Reason Can Lead to God.