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David_Bolin comments on Does Probability Theory Require Deductive or Merely Boolean Omniscience? - Less Wrong Discussion

4 Post author: potato 03 August 2015 06:54AM

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Comment author: David_Bolin 03 August 2015 08:48:15AM 2 points [-]

Basically the problem is that a Bayesian should not be able to change its probabilities without new evidence, and if you assign a probability other than 1 to a mathematical truth, you will run into problems when you deduce that it follows of necessity from other things that have a probability of 1.

Comment author: KnaveOfAllTrades 08 August 2015 10:23:29PM 0 points [-]

Why can't the deduction be the evidence? If I start with a 50-50 prior that 4 is prime, I can then use the subsequent observation that I've found a factor to update downwards. This feels like it relies on the reasoner's embedding though, so maybe it's cheating, but it's not clear and non-confusing to me why it doesn't count.

Comment author: potato 03 August 2015 08:51:11AM *  0 points [-]

How do you express, Fermat's last theorem for instance, as a boolean combination of the language I gave, or as a boolean combination of programs? Boolean algebra is not strong enough to derive, or even express all of math.

edit: Let's start simple. How do you express 1 + 1 = 2 in the language I gave, or as a boolean combination of programs?

Comment author: David_Bolin 03 August 2015 09:04:19AM *  3 points [-]

Probability that there are two elephants given one on the left and one on the right.

In any case, if your language can't express Fermat's last theorem then of course you don't assign a probability of 1 to it, not because you assign it a different probability, but because you don't assign it a probability at all.

Comment author: potato 03 August 2015 09:16:05AM *  1 point [-]

I agree. I am saying that we need not assign it a probability at all. Your solution assumes that there is a way to express "two" in the language. Also, the proposition you made is more like "one elephant and another elephant makes two elephants" not "1 + 1 = 2".

I think we'd be better off trying to find a way to express 1 + 1 = 2 as a boolean function on programs.

Comment author: Lumifer 03 August 2015 02:38:27PM 2 points [-]

I think we'd be better off trying to find a way to express 1 + 1 = 2 as a boolean function on programs.

This goes into the "shit LW people say" collection :-)

Comment author: potato 03 August 2015 02:51:14PM 0 points [-]

Upvoted for cracking me up.