PhilosophyFTW comments on Against Modal Logics - Less Wrong

27 Post author: Eliezer_Yudkowsky 27 August 2008 10:13PM

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Comment author: PhilosophyFTW 07 July 2011 05:15:05AM 1 point [-]

This post demonstrates a deep misunderstanding of modal logics, and of the notions of possibility and necessity. one would expect that misunderstanding given that Eli can't really get himself to read philosophy. For example:

"I have to make an AI out of electrons, in this one actual world. I can't make the AI out of possibility-stuff, because I can't order a possible transistor."

What? What kind of nonsense is this? No contemporary philosophers would ever say that you can make something out of "possibility stuff", whatever the hell that is is supposed to be.

Or this:

"It's going to be because the non-ontologically-fundamental construct of "possibility" turns out to play a useful role in modeling and manipulating the one real world, a world that does not contain any fundamentally possible things."

Eli, everything that is actual is trivially possible, according to every single contemporary analytic philosopher. I have no idea what you mean by "fundamentally possible", but I doubt you mean anything useful by it. If x exists, then it's possible that x exists. If x is an actual object, then x is a possible object. If you want, you can treat those claims as axioms. What's your beef with them? Surely you don't think, absurdly, that if x actually exists then it's not possible that x exists?

One also has to wonder what your beef with meaning is. I mean, surely you mean something and mean to communicate something when you string lots of letters together. Is there nothing you mean by "reductionism"? If you don't mean anything by using that linguistic term, then nobody should pay attention to you.,

Comment author: nshepperd 07 July 2011 07:31:37AM 7 points [-]

Eli, everything that is actual is trivially possible, according to every single contemporary analytic philosopher. I have no idea what you mean by "fundamentally possible", but I doubt you mean anything useful by it. If x exists, then it's possible that x exists. If x is an actual object, then x is a possible object. If you want, you can treat those claims as axioms. What's your beef with them? Surely you don't think, absurdly, that if x actually exists then it's not possible that x exists?

Allow me to attempt to translate (BTW, that a claim is so absurd is evidence it is not being made. Just sayin'.):

EY is not saying that some actual things are not possible. He is saying that things that are not actual, yet "possible", are exactly the same, as far as the universe is concerned, as things that are not actual and not "possible". Specifically, they are all nonexistent. Hence possibility is not fundamental in any ontological sense.

The general gist of the whole post is complaining that for all their precise logic, the people who invented modal logic have still not understood possibility and necessity. They formalized the intuitions about how possibility and necessity work, but didn't solve what they actually are (which is: labels applied by a decision-making algorithm).