The human experience of colour is not really about recognizing a specific wavelength of light.

True, but irrelevant to the subject at hand.

the qualia of colour are associated more with the invariant surface properties of objects than they are with invariant wavelengths of light.

No, the qualia of color have nothing to do with the observed object. This is the pons asinorum of qualia. The experience of color is a product of the invariant surface properties of objects; the qualia of color is a product of the relationship between that experience and other similar experiences.

A human looking at an optical illusion might say, "That looks red, but it's really white," acknowledging that spectral color is objective, but psychophysical color is more malleable. But compare that sentence to "that sounds good, but it's really bad." Statements about color aren't entirely subjective--to some extent they're about fact, not opinion.

Statements about qualia are about the subjective aspect of an experience: e.g., red is the color of rage; of love; the color that means 'stop.'

Your eyes do detect the frequency of light, your nose does detect the chemical composition of smells, and your tongue does detect the chemical composition of food. That's exactly what the senses of sight, smell, and taste do.

Our brains then interpret the data from our eyes, noses, and tongues as color, scent, and flavor. It's possible to 'decode', e.g., color into a number (the frequency of light), and vice versa; you can find charts on the internet that match frequency/wavelength numbers to color. Decoding taste and scent data into the molecules that produce them is more difficult, but people find ways to do it--that's how artificial flavorings are made.

There are lots of different ways to encode data, and some of them are more useful in some situations, but none of them are strictly privileged. A non-human brain could experience the 'color' of light as a number that just happens to correspond to its frequency in oscillations/second, but that wouldn't prevent it from having qualia, any more than encoding numbers into hexadecimal prevents you from doing addition.

So it's not the 'redness' of light that's a quale; 'red' is just a code word for 'wavelength 635-700 nanometers.' The qualia of redness are the associations, connections, emotional responses that your brain attaches to the plain sensory experience.

When a human brain makes a decision, certain computations take place within it and produce the result. Those computations can be perfectly simulated by a sufficiently-more-powerful brain, e.g. Omega. Once Omega has perfectly simulated you for the relevant time, he can make perfect predictions concerning you.

Perfectly simulating any computation requires at least as many resources as the computation itself (1), so AFAICT it's impossible for anything, even Omega, to simulate itself perfectly. So a general "perfect predictor" may be impossible. But in this scenario, Omega doesn't have to be a general perfect predictor; it only has to be a perfect predictor of you.

From Omega's perspective, after running the simulation, your actions are determined. But you don't have access to Omega's simulation, nor could you understand it even if you did. There's no way for you to know what the results of the computations in your brain will be, without actually running them.

If I recall the Sequences correctly, something like the previous sentence would be a fair definition of Eliezer's concept of free will.

(1) ETA: On second thought this need not be the case. For example, f(x) = ( (x *10) / 10 ) +1 is accurately modeled by f(x) = x+1. Presumably Omega is a "well-formed" mind without any such rent-shirking spandrels.

The more I think about this, the more I suspect that the problem lies in the distinction between quantum and logical coin-flips.

Suppose this experiment is carried out with a quantum coin-flip. Then, under many-worlds, both outcomes are realized in different branches. There are 40 future selves--2 red and 18 green in one world, 18 red and 2 green in the other world--and your duty is clear:

(50% * ((18 * +$1) + (2 * -$3))) + (50% * ((18 * -$3) + (2 * +$1))) = -$20.

Don't take the bet.

So why Eliezer's insistence on using a logical coin-flip? Because, I suspect, it prevents many-worlds from being relevant. Logical coin-flips don't create possible worlds the way quantum coin-flips do.

But what is a logical coin-flip, anyway?

Using the example given at the top of this post, an agent that was not only rational but clever would sit down and calculate the 256th binary digit of pi before answering. Picking a more difficult logical coin-flip just makes the calculation more difficult; a more intelligent agent could solve it, even if you can't.

So there are two different kinds of logical coin-flips: the sort that are indistinguishable from quantum coin-flips even in principle, in which case they ought to cause the same sort of branching events under many-worlds--and the sort that are solvable, but only by someone smarter than you.

If you're not smart enough to solve the logical coin-flip, you may as well treat it as a quantum coin-flip, because it's already been established that you can't possibly do better. That doesn't mean your decision algorithm is flawed; just that if you were more powerful, it would be more powerful too.

ISTM the problem of Boltzmann brains is irrelevant to the 50%-ers. Presumably, the 50%-ers are rational--e.g., willing to update on statistical studies significant at p=0.05. So they don't object to the statistics of the situation; they're objecting to the concept of "creating a billion of you", such that you don't know which one you are. If you had offered to roll a billion-sided die to determine their fate (check your local tabletop-gaming store), there would be no disagreement.

Of course, this problem of identity and continuity has been hashed out on OB/LW before. But the Boltzmann-brain hypothesis doesn't require more than one of you--just a lot of other people, something the 50%-ers have no philosophical problem with. It's a challenge for a solipsist, not a 50%-er.

[Rosencrantz has been flipping coins, and all of them are coming down heads]

Guildenstern: Consider: One, probability is a factor which operates within natural forces. Two, probability is not operating as a factor. Three, we are now held within un-, sub- or super-natural forces. Discuss.

Rosencrantz: What?

Rosencrantz & Guildenstern Are Dead, Tom Stoppard

Newcomb's problem is applicable to the general class of game-type problems where the other players try to guess your actions. As far as I can tell, the only reason to introduce Omega is to avoid having to deal with messy, complicated probability estimates from the other players.

Unfortunately, in a forum where the idea that Omega could actually exist is widely accepted, people get caught up in trying to predict Omega's actions instead of focusing on the problem of decision-making under prediction.

IAWY and this also applies to hypotheticals testing non-mathematical models. For instance, there isn't much isomorphism between Newcomblike problems involving perfectly honest game players who can predict your every move, and any gamelike interaction you're ever likely to have.

Thanks for the heads-up. Fixed.

I may be in the minority in this respect, but I like it when Less Wrong is in crisis. The LW community is sophisticated enough to (mostly) avoid affective spirals, which means it produces more and better thought in response to a crisis. I believe that, e.g., the practice of going to the profile of a user you don't like and downvoting every comment, regardless of content, undermines Less Wrong more than any crisis has or will.

Furthermore, I think the crisis paradigm is what a community of developing rationalists ought to look like. The conceit of students passively absorbing wisdom at the feet of an enlightened teacher is far from the mark. How many people can you think of, who mastered any subject by learning in this way?

That said... both "sides" of the gender crisis are repeating themselves, which strongly suggests they have nothing new to say. So I say Eliezer is right. If you can't understand the other side's perspective by now--if you still have no basis for agreement after all this discussion--you need to acknowledge that you have a blind spot here and either re-read with the intent to understand rather than refute, or just avoid talking about it.