Saturday, July 17, 2010

Ultimate Explanations of the Universe

An excellent book by Michael Heller.

Quotes:

"The tendency to pursue 'ultimate explanations' is inherent in the mathematical and experimental method in yet another way (and another sense). Whenever the scientist faces a challenging problem, the scientific method requires him to never give up, never seek an explanation outside the method. If we agree - at least on a working basis - to designate as the universe everything that is accessible to the mathematical and experimental method, then this methodological principle assumes the form of a postulate which in fact requires that the universe be explained by the universe itself. In this sense scientific explanations are 'ultimate,' since they do not admit of any other explanations except ones which are within the confines of the method.

However, we must emphasise that this postulate and the sense of 'ultimacy' it implies have a purely methodological meaning, in other words they oblige the scientist to adopt an approach in his research as if other explanations were neither existent nor needed." - Michael Heller, The Totalitarianism of the Method.


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"The longing to attain the ultimate explanation lingers in the implications of every scientific theory, even in a fragmentary theory of one part or aspect of the world. For why should only that part, that aspect of the world be comprehensible? It is only a part or an aspect of an entirety, after all, and if that entirety should be unexplainable, then why should only a tiny fragment thereof lend itself to explanation? But consider the reverse: if a tiny part were to elude explanation, it would leave a gap, rip a chasm, in the understanding of the entirety."


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"Peter van Inwagen proposed a rather peculiar answer to the question why there exists anything at all. His reasoning is as follows. there may exist an infinite number of worlds full of diverse beings, but only one empty world. Therefore the probability of the empty world is zero, while the probability of a (non-empty) is one.

This apparently simple reasoning is based on very strong an essentially arbitrary assumptions. First of all, that there may exist an infinite number of worlds (that they have at least a potential existence); secondly, that probability theory as we know it may be applied to them (in other words that probability theory is in a sense aprioristic with respect to these worlds); and thirdly, that they come into being on the principle of 'greater probability.' The following question may be put with respect to this mental construct: 'Why does it exist, rather than nothing?'"

9 comments:

Neil B said...

I think the main trouble in that argument over empty v. "filled" possible worlds, is it not explaining our world being *just like this.* It just addresses something instead of nothing. I think it's more interesting to forget the vacua and consider, what if there are infinite possible worlds "really existing" (IOW, being like we are.) Then, what consequences? I posted on that in my own blog, including the issue of ultimate theories. I think the point is short enough to actually adapt here:

The post was based on my comment at Backreaction, under Marcelo Gleiser's guest post explaining it may be a mistake to pursue a final theory of "the" universe (or at least, to think it must be simple/beautiful etc.) I think Marcelo has a good point. Here I delve into the relevant and deep philosophical problems about "why is there something instead of nothing" and "why is it like this and not otherwise." (We should add: is "something" even clearly defined - a point well made by the modal realists.)

We don't have any a priori notion of why "reality" should be like this or otherwise. For deep logical reason I've noted before, I don't see how we can. There is nothing in logical analysis that can "bless" some mathematical constructs with a "right to life" over others - ie, to be incarnate in the special manner we feel that we are. To be, as Madonna put it, "living in a material world." (I like to say, it's like number 23 specially existing also as brass numerals "just because", despite being just another number ...)

Many thinkers cogently argue we can't even make that distinction. I think that collides with our basic feeling of being alive etc. but it is near impregnable as a strict logical critique of material realism being coherently distinct from abstractly descriptive and totally unselective modal realism.

Hence some believe in MUH: that all structures in the Platonic mindscape exist (logically wide-open, a far bigger set than even the wildest string-theory landscape etc.) If so there is little point in looking for a fundamental theory that makes sense or is beautiful etc, because we are just in a possible world that allows us to exist.

However, that presents deep Bayesian expectation problems. If that were true, our greatest expectation would be living in a universe just orderly enough to get us in this condition and to this point, and no more so (because there are so many more ways to do that than to be very neatly consistent, with identical electrons and laws that don't change over time etc. in various odd ways.)

So no one knows what's going on or why it should be or be like this. I think there's some "management" in the sense some ultimate reality has some intrinsic goals or even purposes like beauty and life-friendliness, but it would be wrong to impose that as a working assumption. BTW that would not have to be like a person, FWIW. So: find a TOE that works if you want, but be aware of the logical problem of justifying it existentially.

Steve said...

Hi Allen: So you recommend the Heller book? Does he have much interesting to say about what the ultimate explanation might be (beyond the methodological aspect of this discussed in the quotes)?

Allen said...

Neil, good comment!

Steve,

I really liked the book, though it was very terse - only 216 pages in total. It covered a lot of ground in relatively few words. I'd really have have liked to have seen him expand on his points more.

But as the use of the plural "Ultimate Explanations" in the title implies, it's not about any particular ultimate explanation, but rather about "ultimate explanations" in general.

It's a really good supplement to the usual way that cosmology and cosmogony is presented to the general public. Though, it's so concise that you really have to bring a lot of background knowledge to it in order to get a good grasp of his points.

Which won't be a problem for you, but it would definitely be a hurdle for the average layman.

Heller is a Catholic priest with a PhD in cosmology, and specializes in issues related to general relativity. So, he has a pretty interesting perspective on things.

I can't say that I really learned any new facts from the book - it was more just a very interesting, well articulated (terse, terse, terse) discussion of the issues.

Steve said...

Thanks Allen.

Neil B. Looking at your comment a second time I realized you're making the same argument from a bit different perspective as what philosopher John Leslie was talking about in his book, Immortality Defended, which I just read.

He thinks there would be many more ways for a world to have creatures like us, yet otherwise have much more disorder, compared to the long-term regularity our universe displsys. His answer is a variety of pantheism.

Neil B said...

Allen - if you don't try to "explain" why your experiences are what they are or what coordinates them for you, or even feel sure "if" something coordinates them between you and other minds - then taking phenomenology seems to have even more drastic consequences than just avoiding the idea of a controlling structure of some kind (per physicalism or not as may be.) I can't imagine then why you'd trust your memories of your own experiences, and so all you'd have is "what I'm having as experience content right now." Nor do you have any reason to expect what should happen next. Isn't that rather Spartan, and requires a pretense to act like the regularity is there to be "used" even if you don't "really" believe in it?

Steve: any idea who might be credited with first saying roughly, that if all PWs existed then we'd likely find ourselves in one that was not orderly beyond what allowed us to do the observing? The Wikipedia article on the MUH (similar as to Modal Realism) states [note typo]:

Philosopher Keith Ward has argued that if MUH or any similar highly profligate view of universes is true, then the vast majority of these universes will be very complex. On the other hand, the universe in which we find ourselves is very simple, as evidenced by its intellegibility and elegance. So the MUH fails to explain a fundamental property of our universe unless we assume that by an enormous coincidence we exist within the vanishingly small proportion of simple universes. [10]

It looks like Ward made this argument by 1996, and surely similar has been bandied about before.

(Heh, Captcha was "modess" - is that the "goddess" of the modal multiverse?)

Allen said...

Neil,

So, as to your first point:

"Isn't that rather Spartan, and requires a pretense to act like the regularity is there to be 'used' even if you don't 'really' believe in it?"

So, in other words:

"Why do you act as if a real world exists, if you don't believe that it does."

And my response is: I act the way I act. I don't get to choose. There is no free will. Why don't I act crazy? There is no reason - I just don't (usually). That's just the way my reality is.

Just like if physicalism is true, then the explanation for my sane behavior would be that given the particular laws of physics and initial conditions of our universe, I have no choice but to act sane. Why does our universe have "Sane Allen" initial conditions and causal laws? There is no reason...that's just the way our universe is. Right?

As to your second point:

"if all PWs existed then we'd likely find ourselves in one that was not orderly beyond what allowed us to do the observing"

Actually I think David Lewis addressed this in his book, "On the Plurality of Worlds", pg. 119 in the version that Google Books has online.

I won't type the passage in, but here is a summary of it that I found. As one would expect, his solution relies on infinities!

"Forrest argues that there is a sense in which worlds at which the inductive reasoning of observers fails predominate across the possible worlds, even though the cardinality of the infinitely many deceptive worlds is the same as the cardinality of infinitely many non-deceptive worlds. More particularly, the deceptive worlds might be ones at which Occam's Razor fails such that they include all manner of epi-phenomenal rubbish that does not interact with observers or things observed. As the ways in which otherwise qualitatively identical worlds can include such epi-phenomenal rubbish infinitely outnumber the one way that an otherwise qualitatively identical world might lack any such rubbish, and it is the same for every equivalent class of worlds qualitatively identical save for the inclusion of epi-phenomenal rubbish or its absence, it appears that it is infinitely probable that Occam's Razor fails at the actual world. Lewis responds to this argument from his modal realism to the failure of an important theoretical heuristic with the stance that, if the cardinality of the rubbishy and clean worlds is the same then you can partition equivalence classes any way you want them. They could even be partitioned so that it comes out that the clean worlds predominate and it appears infinitely probable that Occam's Razor correctly predicts the sparseness of existing things at the actual world."

Neil B said...
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Neil B said...

Well, philosophers are usually looking for justification of what you want to do as a thinker, not causal explanation of why you do it. Maybe you can "Wittgenstein" (verb) the distinction away .... You also didn't address previous memories, but I guess you can say you just believe it because you do. But why *should* you as a "good thinker", is the usual question.

Thanks for reference to Lewis and the problem of "more" "rubbishy worlds" if there are infinities of both (and with the continuous nature of the descriptive space, Continuum rather than Aleph null. Oh how annoying not to even know the cardinality of the continuum!) I think Lewis' attempt at defense is shallow and we should be able to have some Bayesian expectation. You know of Pruss's attempt to invalidate statistical reasoning on infinite sets and my attempts to validate such reasoning, at Pruss on infinity and Kalam. I don't know if I refuted the Lewis defense, but surely should force reconsideration of glibness over it.

Steve said...

Thanks for the reminder, Allen. I have Lewis' book in front of me here and you've captured the gist of his defense.
He is responding to Peter Forrest (Occam's razor and possible worlds, Monist, 1982)
George Schlesinger (Possible Worlds and the mystery of existence, Ratio, 1984), John Bigalow (Possible Worlds foundations for probability, philosophical logic, 1976), and a couple of others.

The next section adresses the criticism that if all scenarios exist, doesn't this undermine our caring about morality (all possible bad things happen somewhere regardless of what we do). Lewis says it's pointless to worry about the other worlds.