Why Does the World Exist: An Existentia - By Jim Holt Page 0,109

above that—the first explanatory level—I had jotted down some of the plausible Selectors. And at the level above that—the second explanatory level—I had indicated some of the meta-Selectors. Then I had drawn arrows between the different levels to indicate the various explanatory relationships that might obtain. The diagram looked like the one on the facing page.

“I see you’ve worked out all the logical implications,” Parfit said as he leaned forward and squinted at my diagram.

Most of these implications had already been drawn by Parfit himself, and they were pretty straightforward. The Simplicity Selector, for example, picks out Null possibility from among the cosmic possibilities. Thus, if there had been nothing at all, that would have been explained by the fact that nothingness was the simplest way reality might have been.

Similarly, the Goodness Selector picked out the Axiarchic possibility—a universe consisting only of good worlds. Thus, if reality turns out to take that form, it would be explained by the fact that this was the best way reality could have been. But, if reality did take that form, what could explain the fact that the Goodness Selector ruled? Only that the Goodness Selector, being so good, was itself selected by Goodness at the meta-level. And here, as Parfit had observed, we run into a problem: A Selector cannot select itself. It cannot settle whether it rules unless it does rule. Otherwise put, no explanation of reality is capable of explaining itself.

To indicate that Goodness could not, on pain of circularity, explain itself, I had drawn an “X” across the arrow leading from Goodness at the meta-Selector level to Goodness at the Selector level.

But not all Selectors are prone to this sort of circularity. That is, not all Selectors select themselves. And that fact was reflected in what I felt was the most interesting arrow in my diagram: the one that went from Simplicity at the meta-explanatory level to Null at the explanatory level.

This arrow, too, was inspired by what Parfit had written. At the very end of his “Why Anything?” essay, he had made an alluring observation: “just as the simplest cosmic possibility is that nothing ever exists, the simplest explanatory possibility is that there is no Selector.” I had taken this to mean that the No Selector possibility at the explanatory level is like the Null possibility at the reality level: each would be explained by Simplicity. Then if Simplicity rules at the meta-explanatory level, it would not pick itself as the Selector at the explanatory level. Rather, it would decree that there would be no Selector at all.

Was this indeed what Parfit meant?

“That’s right,” he said with a smile.

And what would reality look like if there were no Selector? Well, it almost certainly wouldn’t take the very special form of nothingness, the emptiest of all cosmic possibilities. “If there is no Selector,” Parfit had written, “we should not expect that there would also be no Universe. That would be an extreme coincidence.” By the same token, it seemed to me, we should not expect it to take any other special form. If there were no Selector, we should not expect reality to be as full as it could possibly be, as good as it could possibly be, as bad as it could possibly be, as mathematically neat as it could possibly be, and so on. Rather, we should expect such a blindly chosen reality to be one of the countless cosmic possibilities that have no special feature at all. In other words, we should expect reality to be thoroughly mediocre. Did Parfit agree with this reasoning?

He nodded that he did.

So if Simplicity is the ultimate Selector, this would explain why there is something rather than nothing! Heidegger, in his fuddled way, may have had a point after all. Das Nichts selbst nichtet: “Nothing noths itself.” If nothingness prevails at the explanatory level, then there is no Selector explaining the way reality turned out. But if there is no Selector, then the way reality turned out would be a random matter. In that case, it would be exceedingly odd if reality turned out to be nothingness. For the Null Possibility is a very special outcome, being the simplest of all cosmic possibilities. So nothing (at the explanatory level) noths itself (at the cosmic level)—with the upshot that reality comprises something rather than nothing. All by dint of Simplicity ruling at the highest level.

If Simplicity is the ultimate explanation of things, this would also account for why the actual cosmos seems