Possible worlds

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I don't see this as merely a matter of faith, besides my own (perhaps partially validated) faith that people generally have the innate capacity for language, and carry intuitions for what statements mean in a given language that are very often naturally the same. After all these intuitions are, roughly speaking, testable: one can test whether interpretations of statements are "intuitive" by seeing how people (say, a test sample) interpret said statements and identifying a consensus. It's not as good as reading their minds, but we can't do that yet.

http://plato.stanford.edu/entries/david-lewis/#6.1

There are four areas in which Lewis thinks that possible worlds earn their keep.

* Modality: Traditional treatments of modal talk in terms of operators face several difficulties. They can't, at least without significant cost, properly analyse talk about contingent existence, or talk about modal comparatives, or modal supervenience theses. All of these are easy to understand in terms of quantification across possibilities.
* Closeness: Our best theory of counterfactuals, Lewis's theory, relies on comparisons between possible worlds. Indeed, it relies on comparisons between this world and other worlds. Such talk will be hard to paraphrase away if worlds aren't real.
* Content: Lewis argues, in part following Stalnaker (1984), that our best theory of mental and verbal content analyses content in terms of sets of possibilities. This, in turn, requires that the possibilities exist.
* Properties: We often appear to quantify over properties. The modal realist can take properties to be sets of possibilia, and take such quantification at face value.

There may be more uses for possible worlds. Of course, none of this should compel us to accept that possible worlds are of the same kind as this world - Lewis defends his particular conception of possible worlds later in the book. Under that conception, there could be no door through which you enter another possible world, so if you went through a black hole and turned up somewhere else, you'd just be in another part of this world.

Here's a more detailed exploration of Lewis' book: http://www.umass.edu/philosophy/PDF/Bricker/Lewis,%20Plurality%20of%20Worlds.pdf

I agree that modal realism does not have as secure a status as most of the theories in science, for example. But if it is better than the alternatives, I am happy to accept it (unless an even better option comes along, of course). If you say that you don't believe in possible worlds, then you're still committing yourself to a particular position - the only way to avoid that is to just be totally agnostic about them.

All human progress depends on making the possible actual. Possibility is an important concept since it can be used to determine what actualities might be brought about. The Possible, we can do. The Impossible we cannot, so it pays to eliminate the Impossible and save time and energy.

ruveyn

Some possibilities are not within our grasp. That doesn't make them impossible in general, though. Possible worlds are not defined as 'situations which are practically possible for humans'.

A belief in multiple universes that cannot be validated is faith. It is absurd that those who declare things like a soul and god are false but then hypocritically declare things such as multiple universes true which have the same amount of evidence as religious scripture.

1. Some could argue that chaos theory provides a mathematical statement allowing the existance of god.

2. Some could argue that some other mathematical statement allows the existance of multiple universes

1. and 2. are both equally absurd and equally realistic/unrealistic. Both can not be demonstrated to our senses. There is no difference on how both scenarios are faith based.

Nonsense. I'm not sure how other people who believe that possible worlds are real approach the topic, but for me, I accept it simply because it is the best option available. If we can get the same benefit at less of a cost, I would be happy to alter my viewpoints. However, I don't think we can do that. This is not the same as faith in God, which, usually, is fairly unshakeable and not open so easily open to argument.

Nobody is saying that we should believe in modal realism just because the existence of other worlds is 'allowed'. It is that the arguments in favour of modal realism outweigh the arguments against it. Certainly, the empirical, observational evidence in favour of modal realism is as empty as is the empirical, observational evidence in favour of souls and Gods. But so what? Why should such evidence form the sole foundations of our beliefs? (In fact, there are many who would argue that it's not even possible, let alone desirable, for it to do so). There are questions that empirical study cannot solve. In these cases we must turn to other methods.

Also, bear in mind that if you accept that the world is (or could be) just a mathematical structure, as Tegmark argues, then it's down to you to say why there is anything metaphysically special about this world. So if you accept the 'mathematical universe' claim, but still hold that possible worlds do not exist, then you are the one with the inflated ontology: you are claiming that there is something unique to this world, something that gives it a status above that of other worlds.

A belief in multiple universes that cannot be validated is faith. It is absurd that those who declare things like a soul and god are false but then hypocritically declare things such as multiple universes true which have the same amount of evidence as religious scripture.
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I have not heard of a chaos theory proof of God, however, the problem I see is that most religions actually have negative proof. That is to say that we have good evidence that the idea is false, rather than merely having no evidence at all.

I suppose one could talk about a random Supreme Being, but even then a theory of such a being is still likely less parsimonious given that cognitively, a mind is a highly complex thing, while "many universes exist" is a much simpler statement to commit to.

These statements (bolded) together in a response strike me as contractadictory (if they are not please clarify).

Personally It seems silly when one declares a theory valid while declaring another belief false, when both the theory and belief have the same amount of evidence (which is essentially none). One contradicts him/herself when declaring a standard to establishing what is real while only declaring that religious beliefs violate this standard and not psuedoscientific theories.

Could you explain why you think they are contradictory? It's difficult to clarify without knowing what your specific objection is.

You seem to think that we should form beliefs based only on empirical evidence, and that beliefs which have the same amount of empirical evidence in their favour are necessarily on equal ground. I completely disagree with this. I think that our knowledge is built on more than that. As I said, there are questions that empirical study cannot solve, and in these cases we must turn to other methods.

In what dimension does the so-called 'pseudoscience' of modal realism lie? Lewis never claimed it was science in the first place.

I have not heard of a chaos theory proof of God, however, the problem I see is that most religions actually have negative proof. That is to say that we have good evidence that the idea is false, rather than merely having no evidence at all.

I suppose one could talk about a random Supreme Being, but even then a theory of such a being is still likely less parsimonious given that cognitively, a mind is a highly complex thing, while "many universes exist" is a much simpler statement to commit to.[/quote]Some view chaos theory as allowing a possibility for the existence of god, but not proof of god.

Regardless of the "evidence" for both a all knowing/all powerful deity is just as unrealistic as multiple universes because we can never know either of them. One being easier to fantasize does not mean one is more likely to exist.

Either you apply a standard to determine what true and false universally, or you accept that the standard is inaccurate.

If you read a little closer into what I'm saying, I don't necessarily support Lewis' belief that possible worlds exist like the actual world does. In fact, I don't support it at all. But I see the possible worlds framework as a working predictive model, and at the same time I tend to separate models from reality.

Moreover, one can be an atheist and still have faith in things that have no evidence (since atheists do not have to commit themselves to only believing in things that have supporting evidence), though as I've said one does not even have to do that here.

Last edited by Hector on 05 Jun 2010, 2:35 pm, edited 1 time in total.

Given how long it took modal realism to emerge, I would say that Gods are far, far easier to fantasize than it is. In any case, people are not just fantasizing and claiming that whatever they come up with is true. There is more going on than that.

You continue to make the mistake of assuming that because two theories have the same amount of empirical, observational evidence, that means there is just as much reason to believe one as there is the other.

You state
"This is not the same as faith in God, which, usually, is fairly unshakeable and not open so easily open to argument."

"Certainly, the empirical, observational evidence in favour of modal realism is as empty as is the empirical, observational evidence in favour of souls and Gods. But so what? Why should such evidence form the sole"

You are stating they are not the same. I view this as contradictory because while stating that you do not view them as the same, you are admitting that they are equally empty in terms of them being excepted as real.

Essentially one is assuming that multiple universes exist as a possibility while declaring another possibility with the same amount of evidence (or lack of) is not possible.

How is this a "mistake" please clarify.

No - I'm saying that they are equally empty in terms of empirical, observational evidence. I am not saying that they equally empty in terms of which would be expected to be real, because I don't take empirical, observational evidence to be the sole foundation of my beliefs. Maybe somebody else can try to explain this to you, because clearly I'm not communicating the point appropriately.