Monday, December 15, 2008

The Multiverse and the Razor

We have from time to time noted that theories of a multiverse suffer from being in stark conflict with the law of parsimony. This is the law that tells us that given several competing explanations for some phenomenon, the simplest explanation that's compatible with the known facts is to be preferred.

Evidently, a commenter at Uncommon Descent has opined that the multiverse theory, the idea that there are, besides our own world, an infinity of universes exhibiting an infinity of laws and parameters, is not incompatible with the law of parsimony. I find this hard to accept, as does Barry Arrington. He explains his reasons here.

Arrington doesn't explain his objection quite as thoroughly as a reader unfamiliar with the multiverse concept might like, but what he's getting at is that any theory that multiplies entities to infinity in order to explain the existence of the unimaginable precision of the fine-tuning of this world is by definition unparsimonious. This is especially true given that there's no evidence of any other universes, much less an infinity of them. All we know is that some versions of string theory allow for them, but we don't even know if string theory is true.

Since the alternative theory is that there is just one world, the world of our experience and the only world we have evidence for, it would seem that that is the simplest hypothesis that fits all the facts and it really is hard to understand how some people justify thinking otherwise.

Anyway, Arrington's post gives us, besides us a bit of unnecessary hyperventilation, a helpful and succinct overview of the law of parsimony, also known as Occam's Razor, and a little background on William of Ockham himself.

Check it out.


Plan B

The U.S. and Britain have urged India not to go to war with Pakistan in the wake of the Mumbai attacks so, according to this report at DEBKAfile, New Delhi has developed a plan B. They've solicited help from Israel to train commandos in quick in/out strikes against terrorist centers and camps in several Pakistani regions. Condaleeza Rice has apparently given tacit approval for such reprisals and the Israelis are currently training the Indian forces.

NATO forces are waging war against the Taliban and al Qaeda in northwest Pakistan and now India will be waging war against various Pakistani terror groups in the southeast. How long can the government in Islamabad ignore all this and still remain stable? At what point does Pakistan have to make a decision to either be a fully committed partner in the war on terror or to side completely with the terrorists? The strip of middle-ground they've tried to occupy for the last ten years is growing increasingly narrow.