Manfred comments on Probability, knowledge, and meta-probability - Less Wrong

38 Post author: David_Chapman 17 September 2013 12:02AM

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Comment author: Manfred 14 September 2013 08:06:51PM *  13 points [-]

I think a much better approach is to assign models to the problem (e.g. "it's a box that has 100 holes, 45 open and 65 plugged, the machine picks one hole, you get 2 coins if the hole is open and nothing if it's plugged."), and then have a probability distribution over models. This is better because keeps probabilities assigned to facts about the world.

It's true that probabilities-of-probabilities are just an abstraction of this (when used correctly), but I've found that people get confused really fast if you ask them to think in terms of probabilities-of-probabilities. (See every confused discussion of "what's the standard deviation of the standard deviation?")

Comment author: Ishaan 14 September 2013 09:47:57PM *  3 points [-]

I think a much better approach is to assign models to the problem ...and then have a probability distribution over models...It's true that probabilities-of-probabilities are just an abstraction of this

Isn't Chapman's approach and your approach completely identical?

As per OP's graphs, each point on the X axis represents a model and the height of the blue line as the probability assigned to that model.

Or did you just mean that your way is a better way to phrase it for not confusing everyone?

Comment author: Manfred 15 September 2013 12:07:42AM *  3 points [-]

Or did you just mean that your way is a better way to phrase it for not confusing everyone?

Right. It's good for not confusing new people, and sometimes also good for not confusing yourself.

Comment author: Ishaan 15 September 2013 12:09:22AM 0 points [-]

Oh ok.

I misinterpreted because you said "better" (implying a difference), and "abstraction" is not necessarily the same as "identical".