We discussed once before that old philosophical puzzler: why is there actually anything at all? Jim Holt’s new book Why does the World Exist? is an entertaining but basically serious assault on this fundamental issue.
Near the beginning he has a splendid chapter about nothing (as it were). He’s a little hard on the Greeks and Romans, suggesting that to them the very idea of zero was inconceivable. That’s surely reading too much into the fact that Roman numerals don’t include a symbol for zero (and you know, the Romans themselves didn’t even use those formal numerals when they needed to do everyday sums, but another system altogether). But his brief history of nothing from Heidegger (‘nothing noths’, apparently) through Bergson to Nozick, and his explanation of the problems that arise from confusing nothing and nothingness, is lively in the best kind of way and stimulating. Could nothing even exist? Holt regards true nothingness as tough to conceive of and spends some time on different ways of attempting the feat. I don’t think I find it that hard myself to think that the world might be null and empty or a Euclidean point (there’s a Greek conception that’s pretty close to zero for you).
That is the question that drives this enquiry, though: why all this stuff? Wouldn’t it be more natural if there was nothing? Much of the book is formed of conversations with selected luminaries, and the first of these, Adolf Grünbaum, simply denies that there’s anything puzzling about the world’s existence. All this stuff about creation of a world out of the void is just a hangover from Genesis as far as he’s concerned. That seems a little too easy. Holt’s second interlocutor, Richard Swinburne, thinks by total contrast that the simplest explanation for the cosmos is, in a word, God, though God himself is inexplicable. That, in a quite different way, seems too easy too.
Holt talks to David Deutsch about a quantum multiverse and Steven Weinberg about Theories of Everything, but both, with refreshing clarity and honesty, deny possessing any ultimate answer to his question. Roger Penrose believes in three separate worlds, but his basically Platonic conception doesn’t seem to offer us anything very new, or to me very satisfying.
With John Leslie things start to get interesting, if bizarre: he believes in axiarchism: the universe exists because of the moral requirement that goodness should exist. There seem to be great difficulties with getting ontology from ethics: attentive observers will have noticed that the moral requirement for goodness doesn’t seem to have much direct causative effect in the real world.
The person Holt is most impressed by is Derek Parfit, who appears (I haven’t read Parfit himself on the subject) to offer not so much a theory as a framework in which all possible universes are theoretically available, but one is actualised by a Selector, a principle which prioritises one. Holt likes this framework and he builds on it a theory of his own. For reasons which were never clear to me, he believes we only need to consider four possible Selectors: simplicity, goodness, fullness/non-arbitrariness, and no Selector at all. Surely there are many more possibilities than that, whatever a Selector is supposed to be (and that’s not quite clear either; for Parfit I suspect it is the kind of intermediate convenience that can be cancelled out of the final solution but Holt seems at times to take it as a metaphysical reality)? Anyway, Holt decides to arbitrate between the Selectors by using them on themselves as meta-Selectors. He thinks only two emerge from this exercise: Simplicity and Fullness. He concludes that if all selectors or no selectors are going to be applied as a result, we end up with a universe of surpassing mediocrity. That seems to be his final view: the world exists like this because it was the most mediocre option the cosmos could come up with. Amusingly he goes on to ask: what could be the reason for my own existence in such a Universe?
Not a convincing conclusion, then, but an intelligent account of the kind that causes the reader to nod in sage agreement or exclaim in frustration by turns.