Academian comments on Second-Order Logic: The Controversy - Less Wrong

24 Post author: Eliezer_Yudkowsky 04 January 2013 07:51PM

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Comment author: Academian 06 January 2013 07:17:22AM *  1 point [-]

That was imprecise, but I was trying to comment on this part of the dialogue using the language that it had established

Ah, I was asking you because I thought using that language meant you'd made sense of it ;) The language of us "living in a (model of) set theory" is something I've heard before (not just from you and Eliezer), which made me think I was missing something. Us living in a dynamical system makes sense, and a dynamical system can contain a model of set theory, so at least we can "live with" models of set theory... we interact with (parts of) models of set theory when we play with collections of physical objects.

Models being static is a matter of interpretation.

Of course, time has been a fourth dimension for ages ;) My point is that set theory doesn't seem to have a reasonable dynamical interpretation that we could live in, and I think I've concluded it's confusing to talk like that. I can only make sense of "living with" or "believing in" models.

Comment author: Eliezer_Yudkowsky 06 January 2013 01:55:56PM 4 points [-]

Set theory doesn't have a dynamical interpretation because it's not causal, but finite causal systems have first-order descriptions and infinite causal systems have second-order descriptions. Not everything logical is causal; everything causal is logical.