Possible worlds semantics

00:00 - Intro
01:26 - Semantics
03:09 - Possible worlds
04:54 - Possible worlds semantics
07:43 - Modal logic
10:01 - Propositions
14:35 - Supervenience
16:46 - A philosophical success!
17:27 - Problems for possible worlds
21:19 - Impossible worlds semantics

If there’s a topic you’d like to see covered, leave me a comment below.

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#philosophy #semantics

[tomholroyd]

It is also useful to think in terms of Actors. An Actor is a "possible world" of beliefs or other data, who interacts with -> other Actors who have possibly different or inconsistent data.

[chrissurfleet]

Such a great way of putting this. I'll be using this with people for a while I imagine ❤

[tomholroyd]

19:13 Sherlock Holmes famously used negative logic. Instead of trying to find tautologies, he would "eliminate that which is impossible, and whatever remains is the truth".

[DarrenMcStravick]

a truthmaker semantics vid is in store 🤔

[tongued]

To say I am metaphysically conservative would be an understatement. I am a metaphysical Luddite. Get rid of quantifiers!

[mikejurney]

Very interesting discussion. Love the enthusiasm! So what must be true in every possible world? Each possible world consists of the conjunction of every little thing in it. But does this specify any general rules of interaction? Can the laws of physics be derives from this conjunction of things? The answer can be found if you look up, "efforts to derive the laws of physics from the principles of logic alone". Is seems the laws of physics must be the same in every possible world.

[ZishanWazedBegg]

If propositions are sets, but how can we understand that sets having propetrites of being True/False?

[MatthewMartinDean]

Still thinking about this- is accessibility a choice of someone thinking about the various possible universes or would there still be accessibility relationships if there wasn't anyone thinking about these universes? i.e. is there a rule to say which pairs of universes have lines and what directions or is that some sort of belief? Are those accessibility lines line time, i.e. this universe could turn into that?

[jasnesciemnienie]

Could you say something more about applications of possible world semantics in those non-philosophical matters you mentioned? It's hard for me to see how it could be used in computer science or economics

[EduardoRodriguez-duvd]

Humans do not determine what is possible in reality. Reality determines it.

Humans constantly and continuously learn what is possible in reality.

No meaning is absolute. Nothing is absolute. This includes that no truth is absolute.

Logic is a simplification of the regularities and apparent causal relationships distinguished in reality, and it is a work in progress.

Within this framework, nothing has a probability of certainty or existence of 100%.

Some things and circumstances have a higher probability of existing than others, but none have guaranteed existence in the terms understood at a given moment.

[tongued]

Also you DO know both 1+1=2 and Fermat's theorem, you just wouldn't be comfortable with the symbolic expressions of the latter.