Possible Worlds

David Lewis's Modal Realism (unicorns are real!), and its pros and cons.

[snaiil.]

love your videos Simon <3 extremely educational am blessed to have acess to resources like yours!!!

[rezamahan]

thank you, professor, for much much-needed lecture on this topic for my logic course👌

[danwylie-sears]

My impression before listening: it can't possibly make any difference whether possible worlds are overtly part of one's ontology, or whether counterfactual statements are handled is some other way. Our reasoning in physics acts on descriptions of the world, not on the world itself. When we say "if you extend a vacuum tube from the top of the Leaning Tower of Pisa to the ground, and drop a feather and an anvil ...", the subsequent reasoning works just as well regardless of whether or not there is a possible world in which you do so. You can even accept the entire collection of possible worlds as actual reality, say that you believe the Flying Spaghetti Monster exists in all of them and that His noodly appendage protects the tower from ever being besmirched with vacuum tubes, ever, in any possible world, and still do the physics about what would happen if the anvil and feather were dropped and not hindered by air. Nor does it have to be physics. You can talk about what minds do -- or what chemical mixtures do, or hurricanes, or populations of caterpillars preyed upon by birds -- on a crudely empirical basis, without having a sufficiently deep explanation of how they work to be able to ground it in physics, and your theory can still be a theory that correctly describes them within the scope of its applicability. Your theory will still authorize chains of reasoning that act on descriptions of the world, not on the world itself, just as physics does. So the existence of possible worlds won't matter there either.

Now to see whether the lecture changes my mind.

[daniel-zhqc]

If only rasheed wallace knew there was a world where he was getting blasted in a modal logic

[muhammadshahedkhanshawon]

Conceivability is a worst system for metaphysics..