Graham Oppy is a cream of the crop atheist philosopher. His book The Best Argument Against God (Palgrave Pivot, 2013) is a state of the art attack on theism. I'd like to evaluate one of his arguments.
…the initial causal state might have been other than it actually was–even though God could not have failed to exist–because God's initial disposition to make other things could have been other than it actually was (either because God could have failed to have an initial disposition to create, or because God could have had initial dispositions to create that differed from the particular initial dispositions to create that he actually had in the initial state.) (13).
The first piece of data that we introduce is the observation that there is a global causal structure: the world is a network of causal relations. One of the standard philosophical questions is, "why is there something rather than nothing?" In the present context we interpret this question to mean "why is there causal stuff, rather than complete absence of causal stuff"?
How Theist answers this question depends upon the view that Theist takes of the scope of possibility. If Theist supposes that every possible world is one in which God engages in causal activity, then Theist can say: it was impossible for there to be complete absence of causal stuff. In other words: there is causal stuff because there had to be causal stuff. If Theist has a more relaxed view of the scope of possibilities–and, in particular, if Theist supposes that it is possible that God might have engaged in no causal activity–then Theist will say: there is no reason why there is causal stuff rather than complete absence of causal stuff–it is a brute fact that there is causal stuff (23-24).
…there is a serious problem for proponents of cosmological arguments that arise with the question "from whence came the causal order?" Once we focus our attention on the global causal order–and not on the question whether the natural causal order itself has a cause–we see clearly that considerations about the shape of the global causal order do not differentially support either Theism or Naturalism (26).
Could God have chosen to make a universe that lasts for less than a second? Could God have chosen to make a universe that blows apart so rapidly that it is mostly empty space? If we suppose that the answer to either of these questions is affirmative, then we cannot also say that God must have all-things-considered reason to prefer a "life-permitting" universe to one of these "non-life-permitting" alternatives. But, if God needn't have all-things-considered reason to prefer a "life-permitting" universe to one of these "non-life-permitting" alternates, then, on the assumption that God's choosing is a brute fact, it surely does turn out that Theist has no better explanation that Naturalist for why it is that relevant cosmic parameters take the values that they do (29-30).
i) Broadly speaking, I think Oppy is saying both theism and atheism must admit that reality is ultimately arbitrary. You run out of explanations. You bottom out with brute factuality. Therefore, theism has no greater explanatory power than atheism–although it may have less explanatory power, given other considerations. In addition, Oppy is targeting the fine-tuning argument in particular, as well as cosmological arguments generally.
ii) I think that much is clear. However, the detailed reasoning by which he attempts to justify his conclusion is obscure. What makes him think "why is there something rather than nothing?" is synonymous with "why is there causal stuff, rather than complete absence of causal stuff"? The phrase "causal stuff" is hardly self-explanatory. Indeed, that's a good deal less clear than the Leibnizian question.
iii) It's unclear what he means by "every possible world is one in which God engages in causal activity". Does he mean the metaphysical relationship between God and possible worlds? If so, a standard theistic explanation is that possible worlds are divine ideas. God's compete concept of possible world history. Possible worlds are constituted by the mind of God. By God's infinite imagination. And in that respect, possible worlds are necessary ideas.
On that construction, possible worlds aren't brute facts. Rather, there's an underlying explanation for their existence. A dependence-relation. They exist because God exists.
iv) However, the point he seems to be driving at isn't the ontology of possible worlds, but why some possibilities are reified while other possibilities remain unexemplified. Not so much, why are there possible worlds, what's the explanation for possible worlds–but what caused this set of possibilities to be actual rather than another?
That's certainly where Leibniz is coming from. When Leibniz asks, "why is there something rather than nothing," what he has in mind is more specific. Not just in general why is there something rather than nothing, but why does this particular something exist rather than something else. Why does the real world exemplify this set of possibilities rather than an alternative set of possibilities? What selects for that when other possibilities were available?
For Leibniz, this implies personal agency. Someone (i.e. God) had to make that selection. Given the number of possible worlds, God had to choose which possible world to instantiate.
v) Now, Oppy's contention seems to be that if the real world is contingent rather than necessary–contingent because it might have been otherwise–then God's choice (if there is a God) is arbitrary. A brute fact. Like rolling the dice. And in that event, theism has no more explanatory power than atheism.
But if that's what Oppy has in mind, then his comparison is fallacious. God could have a reason for preferring one possible world over another because different possible worlds are…different. Different possible worlds have different histories. God opts for one rather than another because one world history is more interesting than another. Has greater values. The way some novels and movies have more interesting characters and more meaningful plots than other novels and movies.
vi) Perhaps, though, hovering in the background of Oppy's discussion is a point of tension in Leibniz. For Leibniz, God had sufficient reason to instantiate this world because this is the best possible world. That's why God chose this world over some other world. But that seems to be necessitarian. God had to choose the best. His hands were tied.
But of that's what underlies Oppy's argument, I'd make two observations:
vii) We can deny that there is one best possible world. Different possible worlds have different histories. Different histories have different goods. No one possible world combines all goods because no one possible world combines different histories. Each possible world exemplifies a single history. There is no best possible world, for each possible world has some goods absent from another possible world. (There may be some possible words devoid of good, but God wouldn't choose one of those.)
viii) In addition, it isn't clear that God is confronted with a binary choice, where he must choose just one option to the exclusion of others. In principle, God could create a multiverse that exemplifies many alternate histories.
Finally, let's consider Oppy's view of what possible worlds are:
I think that the best position for Naturalist to adopt is one according to which theism is impossible. All possible worlds share an initial segment in the actual world. All possible worlds evolve according to the same laws as the actual world. It is impossible that the actual laws could oversee a transition from a purely natural state to a state in which there are supernatural entities. There have never been any supernatural entities. So supernatural entities are impossible; and hence, in particular, gods are impossible. Graham Oppy, "Arguments for Atheism," S. Bullivant & M. Ruse, eds. The Oxford Handbook of Atheism (OUP, 2013), 57-58.
i) I agree with him that "it is impossible that the actual laws could oversee a transition from a purely natural state to a state in which there are supernatural entities." But, of course, that only follows from a naturalistic definition of possible worlds.
ii) It's unclear what he means by evolving possible worlds. If, say, we view possible worlds as abstract objects (or divine ideas), then they are static. Each possible world has a complete history. Perhaps, though, Oppy is using "evolve" as a synonym for the succession of events.
It's like shooting a movie. Once you shoot the movie (and edit the movie), the movie is complete. It has a complete plot. But that allows for plot developments within the movie. Likewise, viewing the movie takes time.
iii) Why does Oppy think "all possible worlds share an initial segment in the actual world"? Maybe because, as an atheist, he thinks the physical universe is all there is. That's the whole of reality. So possibilities must be variations on the physical universe or actual world.
Mind you, that fails to solve the problem that possible worlds were invoked to explain in the first place. In the nature of the case, what might have been didn't happen in the actual world. So what makes counterfactuals true? It can't be a fact in the actual world. For that alternate course of events never took place in the actual world.
iv) From the standpoint of Christian metaphysics, the actual world is not the standard of comparison for possible worlds. The actual world is just one possible world among many. It's is simply distinguished from other possible worlds by actuality. God chooses to objectify that particular idea in time and space.
Some possible worlds have overlapping histories. Up to a point they have the same past, then split off in different directions. Other possible worlds have histories that don't intersect. A different past as well as a different future. So they have nothing in common.