Let's say I wanted to solve my dating issues. I present the following approaches:

1. I endeavor to solve the general problem of human sexual attraction, plug myself into the parameters to figure out what I'd be most attracted to, determine the probabilities that individuals I'd be attracted to would also be attracted to me, then devise a strategy for finding someone with maximal compatibility.

2. I take an iterative approach: I devise a model this afternoon, test it this evening, then analyze the results tomorrow morning and make the necessary adjustments.

Which approach is more rational? Given sufficient time, Approach 1 will yield the optimal solution. Approach 2 has to deal with the problem of local maxima and in the long run is likely to end up worse than Approach 1. An immortal living in an eternal universe would probably say that Approach 1 is vastly superior. Humans, on the other hand, will die well before Approach 1 bears fruit.

While rationality can lead to faster improvement using Approach 2, a rationalist might try Approach 1, whereas a non-rationalist is unlikely to use Approach 1 at all.

Simple amendments to the general problem such as "find the best way to get the best date for next Saturday" will likely lead to solutions making heavy use of deception. If you want to exclude the Dark Arts from the solution space, then that's going to limit what you can accomplish. The short-term drawbacks of insisting on truth and honesty are well-documented.

H proves that it can't decide the question one way or the other.

H is literally defined as either returning true or false. Or it can run forever, if it can't find a proof. It's possible to create another program which does return "UNDECIDABLE" sometimes. But that is not H.

The point is that the behavior of H is paradoxical. We can prove that it can't return true or false without contradiction. But if that's provable, that also creates a contradiction, since H can prove it to.

Not only can H not decide, but we can't decide whether or not H will decide. Because we aren't outside the system, and the same logic applies to us.

I just tried this 'battleground god' thing and it told me:

'It is strange to say that God is a logical impossibility, but you don’t know whether God exists. If God is a logical impossibility, then surely She can’t exist, and so you know that She doesn’t exist.'

I don't get it. Why can't I be unsure about the truth value of something just because it's a logical impossibility? My understanding of logic isn't exhaustive.

I'm very confused about something related to the Halting Problem. I discussed this on the IRC with some people, but I couldn't get across what I meant very well. So I wrote up something a bit longer and a bit more formal.

The gist of it is, the halting problem lets us prove that, for a specific counter example, there can not exist any proof that it halts or not. A proof that it does or does not halt, causes a paradox.

But if it's true that there doesn't exist a proof that it halts, then it will run forever searching for one. Therefore I've proved that the program will not halt. Therefore a proof that it doesn't halt does exist (this one), and it will eventually find it. Creating a paradox.

Just calling the problem undecidable doesn't actually solve anything. If you can prove it's undecidable, it creates the same paradox. If no Turing machine can know whether or not a program halts, and we are also Turing machines, then we can't know either.

If you asked me whether I'd like to live another thousand years (assuming no physical or mental degradation), I'd ask >myself "Why would I want to live 1,000 years?" and, failing to find an answer, decline.

Isn't the obvious answer, "because, assuming your life isn't unbearably bad, living the next 1,000 years has higher expected utility than not living the next 1,000 years?"

Responses like yours confuse me because they seem to confidently imply that the future will be incredibly boring or something. It's possible, but the opposite could also be true. And even if it was unexpectedly bad, you'd still likely be able to opt out at any time.

Honestly, I don't even find the prospect of living another decade all that exciting. If it's anything like its predecessor, my expectations are low. If I were to suddenly die in that time I wouldn't think it a big loss (albeit my family might not like it so much), but if I'm alive I'll probably manage to find some way to pass the time.

If you asked me whether I'd like to live another thousand years (assuming no physical or mental degradation), I'd ask myself "Why would I want to live 1,000 years?" and, failing to find an answer, decline. If I were told that I was going to live that long whether I liked it or not, I'd treat it more as a thing to be endured than as an exciting opportunity. The best I'd expect is to spend the time reasonably content.

Needless to say, I wouldn't make any great sacrifice today for that kind of longevity. If I avoid wanton hedonism, it's because that lifestyle can lead to accelerated degradation and the associated problems. Concern about longevity hardly enters into my calculations.

Confidence is based on your perception of yourself. When someone tells you to be more confident, it's probably because they believe your perception of yourself is worse than reality. Excessively low confidence is no less of a delusion than excessively high confidence.

Small quibble: +- at the end.

[EDITED to be less spoilery.]

Used rot13 to avoid spoilers:

K unf qrafvgl N * rkc(-k^2 / 32) jurer N = 1/(4 fdeg(2cv))

L unf qrafvgl O * rkc(-l^2 / 2) jurer O = 1/fdeg(2*cv)

Fvapr gurl'er vaqrcraqrag gur wbvag qrafvgl vf gur cebqhpg bs gur vaqvivqhny qrafvgvrf, anzryl NO * rkc(-k^2 / 32 - l^2 / 2). Urapr, gur pbagbhe yvarf fngvfsl -k^2 / 32 - l^2 / 2 = pbafgnag. Nofbeovat gur artngvir vagb gur pbafgnag, jr trg k^2 / 32 + l^2 / 2 = pbafgnag, juvpu vf na ryyvcfr jvgu nkrf cnenyyry gb gur pbbeqvangr nkrf.

Guvf vf gnatrag gb gur yvar K = 4 ng gur cbvag (4,0). Fhofgvghgvat vagb gur rdhngvba sbe gur ryyvcfr, jr svaq gung gur pbafgnag vf 1/2, fb k^2 / 32 + l^2 / 2 = 1/2. Frggvat k = 0 naq fbyivat sbe l, jr svaq gung l = 1.

By "naive" I just mean calorie restriction without any other consideration.

Well, of course. I never said or implied calories were the whole ball game. You're conflating weight loss and nutrition throughout.

A low-carb diet is not just a matter of eating what you normally eat, minus the carbohydrates.

No, but you'd be hard pressed to make up those calories by eating proteins. That is quite the point.

It's an empirical fact that some foods are more filling than others and keep you feeling full for a longer period of time, even if the number of calories consumed is the same.

I've mentioned satiation as a real issue that ought to be addressed by any rational diet plan.

But, again, it isn't the aim that a diet should involve no hunger when compared to your current meal plan. That is just plain silly and irrational.

Losing weight is like any other pursuit—it requires the expenditure of resources: Will power, focus, effort, energy, discipline. It may diminish your capacity to pursue other things for a time. It doesn't mean you have to be bedridden or incapacitated. Again, any other pursuit is like this: Working long days on a big project at work, training for a taxing athletic event, studying for difficult classes and exams, etc. Dieting is a significant project to take on.

There seems to be this idea floating around that you can diet, lose lots of weight, and not have it consume some bandwidth in your life. BS. There are some great, rational hacks available, but it takes some sustained work to lose weight. There isn't anyway around that.