SilasBarta comments on Reacting to Inadequate Data - Less Wrong

-3 Post author: MrHen 18 December 2009 04:25PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Article Navigation

Comments (21)

Comments (21)

You are viewing a single comment's thread. Show more comments above.

Comment author: Morendil 18 December 2009 05:49:51PM *  10 points [-]

This post seems made to order to apply recently acquired knowledge. If I come across as pedantic, please attribute that to learner's thrill. From Probability Theory:

"Seeing is inference from incomplete information". -- E.T. Jaynes

Your usual sensory information is inadequate data. You're dealing with that every day. This seems a good starting point to generalize from; brains in vats seem like overkill to approach the question.

Alice and Bob are faced with a scenario of decision in uncertainty. Probability theory and decision theory are normative frameworks that apply there. All the information you've given is symmetrical, favoring no choice over the other.

  • Should Alice or Bob do anything at all ? That depends on the consequences to them of guessing one way or the other, or not guessing at all. If the outcomes are equally good (or equally bad) guessing randomly is optimal.
  • Should they act differently ? There's nothing in the information you've provided that seems to break the symmetry in uncertainty, so I'd say no.
  • Should they circle more than one color ? ... And other variants - you've given no reasons to prefer one outcome to another, so in general we can't say how they should act.
  • If Alice and Bob could coordinate ? They would (as far as I can tell by assessing the information given) have no more definite information by pooling their knowledge than they have separately.
Comment author: SilasBarta 18 December 2009 08:07:50PM 2 points [-]

Very well-put, Morendil. The decision one should make here depends on the consequences of erring one way or the other and so there's insufficient information. One quibble though:

Your usual sensory information is inadequate data. You're dealing with that every day. This seems a good starting point to generalize from

It's true, but I don't think there's anything such as "adequate data" to compare to. In a sense, all data is going to be inadequate. David MacKay's cardinal rule of information theory is, "To make inferences, you have to make assumptions." No matter how much data you get, it's going to be building on a prior. The data must be interpreted in light of the prior.

Human cognition has been refined over the evolutionary history to start from very good priors which allow it very accurate inferences from minimal data, and you have to go out of your way to find the places where the priors point it in the wrong direction, such as in optical illusions.

Comment author: Morendil 18 December 2009 09:38:43PM 1 point [-]

I wouldn't call it a quibble: I agree. There is a lovely tension between the idea that all perception, not just seeing, is "inference from incomplete information"; and the peripatetic axiom, "nothing is in the intellect that was not first in the senses".

The only way to have complete information is to be Laplace's demon. No one else has truly "adequate data", and all knowledge is in that sense incertain; nevertheless, inference does work pretty well. (So well that it sure feels as if logic need not have been "first in the senses", even though it is a form of knowledge and should therefore be to some extent incertain... the epistemology, it burns us !).

Powered by Reddit Powered by Reddit