I’m quite happy to ditch possibility as a dimension in the physics sense. But…
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If the extra dimensions are so small as to be detectable only by gravity, how do you ‘glimpse’ a five dimensional shape? And what does it mean to say that you can visualise anything more than 3 dimensions? Can you visualise the entirety of a four dimensional shape at the same time? I can’t even visualise the whole of a three dimensional shape at the same time. You’I have to turn it round to see the back of it. Anyone can have a vague idea of how it would be if we COULD perceive it, but that’s not the same as visualising it is it? I’m marginally sceptical (although obviously willing to be persuaded if you can explain it for me) that this seeing in more than 3 dimensions business makes any sense.
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Ontological problems - There are many different philosophical theses about possible worlds. David Lewis is extreme, because it posits that all possible worlds have the same ontological status of the real world and that actuality is just indexical (to the world you’re in). That’s rather expensive ontology. (I never said it was an argument against it, just a con.) So then you have all the many variants of actualism, combinatorialism, modal fictionalism… which attempt to do away with the need for an infinite number of existing worlds.
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I don’t know what this ‘religious’ argument business involves, but the moral argument I assume you’re talking about is the one that says people don’t have to worry about their actions because in another world, all is well, and if all worlds are ontologically the same, why should we care about which world is better off. Well, if people really believe that’s objectionable, then I just say accept it as a fact that it doesn’t matter and move on, because even if it is true, society would not let people act in an immoral fashion. (You can apply the same sort of argument to determinist doomsaying as well.) If I came along and threw your cat out of the window, then said that you shouldn’t care because your cat is alive in a nearby possible world, you will definitely not be appeased, however right I am. You will instead lamp me one with the nearest heavy object. Then if this is constantly repeated, I’ll learn that even though no one should care that their cats are being thrown out of the window, I keep getting battered whenever I do it. Therefore, I’m going to stop throwing cats out of the window in order to stop getting hurt, even though I’m right. I will accept as part of my code of conduct that I don’t throw cats out of the window. So it’s just not going to happen that morality will disappear because of the existence of possible worlds, even if ethics just becomes an illusion. I think this sort of hints a bit that ethics really has its grass roots in accomadating and expanding originally evolutionary instincts, which is going to keep the average Joe nicely concerened with solely world-bound matters, at any rate.
(Or if it’s the variant of that which says we shouldn’t care about the third world because there’s a third world where the situation is reversed in a nearby possible world, well that’s just not really worth arguing. We’d want the unhappy people in all worlds to be helped, not none of them.)
- Which just leaves ‘logico-semantic’… What exactly do you mean by that? (I don’t remember which one is Putnam’s argument offhand, although I think it was mentioned in Lewis’ book, or somewhere I might have seen it anyway.)
-James
