Why is there something—anything at all—when there could have been just nothing? The early modern philosopher Leibniz first posed this question, which Grünbaum, a philosopher of science, recently called the Primordial Existential Question. But what exactly is this question asking?
The question’s initial context is Leibniz’s cosmological argument for God’s existence. That argument is essentially that the Principle of Sufficient Reason demands an ultimate explanation that naturalistic science can’t offer. Reason cries out for a metaphysical explanation of all existence, not just for causal explanations which posit one contingent thing or state of the world to account for something equally contingent. Such partial explanations can never be fully satisfying, since if the series of natural things is infinite and so every part of the world is adequately explained in terms of some other part which causes it, one question yet remains to be answered: why is there anything in the first place, rather than nothing at all? The whole of nature must be understood in terms of something unnatural, some necessary being that lies outside the causal chain. That necessary being is supposed to be God.
The standard, logical response to this argument is that it commits the fallacy of composition. Just because something applies to a part doesn’t mean it applies to the whole; just because finite, contingent phenomena are usefully explained by positing causal relations between them, doesn’t mean the whole universe which contains all those phenomena as its parts is just as usefully explained as being an effect of some cause, a product of a necessary being. Causal explanations are inductive in that they’re based on our many experiences of regularities that hold in the interactions between finite, contingent things. You eat a hot dog, the mustard spills and lands on your shirt, staining it. The one event causes the other, under the right circumstances. But we occupy only one universe and haven’t even once experienced the whole of it. So the metaphysical or theological account that the whole of nature must be produced by a supernatural being isn’t as reliable an explanation as an inductive one of a pattern connecting some parts of the natural whole.
This response, though, amounts to little more than casting aspersions on Leibniz’s argument, since the response is consistent with Leibniz’s main point. The whole point is that scientific, probabilistic explanations are limited to the finite and contingent parts of the world, but that reason in general can ask a further, metaphysical question. The issue, then, is whether reason extends beyond science or reliable, probabilistic, quantifying, experience-based logic. If we think of reasoning pragmatically, interpreting reason as the more or less useful tinkering with mental models, we needn’t discount metaphysics or even theology because it’s not a branch of modern science. True, just because we can ask a speculative question doesn’t mean we can reason usefully about possible answers to it. Still, the point about the fallacy of composition begs this deeper question. The typical critic of the cosmological proof scientistically dismisses the metaphysical question of whether the entire causal chain making up the natural universe’s history is itself something that could be explained at all and would be explained only by positing something supernatural. Certainly, just because causal explanations work in one context, doesn’t mean they work in another. We have no experience of other universes, so we don’t know why one would have resulted rather than another; we have no objective basis for assigning probabilities to something compared to nothing, so we don’t know whether without God there should have been nothing at all, because nothingness is supposedly simpler than a natural series of causes and effects. This is all true, but is so only as far as it goes. Again, we have no empirical grounds for speaking with precision about being or of nonbeing in general. We haven’t quantified such entities and we can’t run experiments to test hypotheses concerning them. But this doesn’t mean a metaphysical question about natural things in general is irrational or irresponsible.