It comes down to a matter of levels of abstraction. If you think reality only operates on a single level (reductionism) then you’ll go for MWI. If on the other hand, you think reality is best divided into different levels of abstraction, you’ll be sympathetic toward Bohm.

An analogy might be the relation between deduction and induction; if deduction is just a special case of induction, does that mean we can dispense with the notion of deduction? By analogy, if the particle is somehow just a part of the pilot wave, can we dispense with the notion of the particle? I lean towards a ‘no’ answer in both cases.

In Bohm, reality has a three level structure – the wave function is split in two – there’s the basic wave function at the top level, a new quantum potential at the mid-level, and the particle on the bottom level. All three levels are equally real. Although in Bohm there is no wave function collapse and all branches are equally real, there is only one actual concrete particle history (one world).

Again, I must emphasize, this is a perfect match to my own recursive 3-level ontological model, which has really startled me.

That is exactly correct, but you miss the critical point of this willful ignorance, (no, you even join ranks with them), that this is also the reason that physicists are the cranks, since the weak interpretation is not what is observed… duh.

http://dorigo.wordpress.com/2008/06/23/guest-post-rick-ryals-the-anthropic-principle/

I don’t think the “perceived flaw” of string theory is higher dimensions. In fact, that’s an enormous asset, if for instance you think anthropics is the only way to explain the cosmological constant.

I would guess the loop folks would say the flaw in string theory is that it has to take for granted a “background” Minkowski metric, whereas one hopes a fundamental theory incorporating GR would not have to make any prior assumptions about the background geometry. But I’m not very initiated into either school.

Thus, aside from a few who I would consider cranks, physicists believe in anthropic arguments only insofar as they believe in a multiverse.

Regarding AI, I suspect a physicists belief in this is independent his/her position on (1) and (2)… so “correlation” might not be a good word. Maybe I am missing something, but to me the question is merely is it in principle possible to emulate a human mind using a device that is not merely a copy of the human brain. Physicists, regardless of positions (1) and (2), tend not to believe in a “soul” — and I think for most the question would boil down to whether thoughts ultimately reflect only the processing of information, in which case one accepts the possibility to build a computer to do the same (though the necessary resources could be enormous, and civilization may end before we figure it all out). Perhaps physicists readily accept the proposition because they are unaware of what is supposed to be the subtlety (that’s sort of how I feel).

>Many worlds takes Schroedinger’s equation seriously.

So do numerous alternative explanations. I think Yudkowsky successfully rebutted all explanations involving the notion of a ‘wave-function collapse’ in his series on this blog, but readers should be aware that numerous other alternative explanations still remain. The Bohm interpretation, for example, has no wave-function collapse (according to this interpretation reality is stratified into different levels – both wave-function and particle levels equally ontologically real – this is a similar idea to my own ’3-level causality’ theory.)

See for example, the good wikipedia article summarizing the ontology of some of the more popular alternatives (go to comparison table at end):

Ontology of QM Interpretations

>Marxism does not take market economics seriously but rather is itself a bad, alternative, crackpot theory.

I agree, but Marxists are not likely to see it that way. And in fact, its opposite number, Libertarianism, could also be regarded as just as crackpot. Even moderate versions are certainly not regarded as ‘rational’ by main-stream economists.

Few take anthropics seriously. It is usually used as a sort of ‘God of the gaps’ – once causal explanations of something are available, you can dispense with anthropics, for instance anthropic arguments are used to explain the cosmological constant only because there is currently no causal explanation, once one is available, I bet that anthropics will be dropped like a hot-potato.

I want to suggest that the believers in this belief cluster are not nearly as ‘rational’ as they think. They just fancy themselves as ‘cool smarties’.