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Comment author: Epictetus 19 September 2015 08:00:30PM 2 points [-]

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.

Comment author: Houshalter 27 August 2015 02:04:40AM *  0 points [-]

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.

Comment author: Epictetus 27 August 2015 02:19:17AM *  0 points [-]

I did overlook the definition of H. Apologies.

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.

More precisely, H will encounter a proof that the question is undecidable. It then runs into the following two if statements:

if check_if_proof_proves_x_halts(proof, x, i)

if check_if_proof_proves_x_doesnt_halt(proof, x, i)

Both return "false", so H moves into the next iteration of the while loop. H will generate undecidability proofs, but as implemented it will merely discard them and continue searching. Since such proofs do not cause H to halt, and since there are no proofs that the program halts or does not, then H will run forever.

Comment author: [deleted] 25 August 2015 11:40:54AM *  2 points [-]

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.

In response to comment by [deleted] on Open Thread - Aug 24 - Aug 30
Comment author: Epictetus 27 August 2015 02:04:28AM *  1 point [-]

Why can't I be unsure about the truth value of something just because it's a logical impossibility?

If you're using logic to determine truth values, then a logical impossibility is false. The reason is that if something is logically impossible, then its existence would create a contradiction and so violate the Law of Noncontradiction.

Comment author: Houshalter 26 August 2015 06:31:34AM *  1 point [-]

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.

Comment author: Epictetus 27 August 2015 01:33:05AM 0 points [-]

From the link:

That means that we can’t actually prove that a proof doesn’t exist, or it creates a paradox. But we did prove it! And the reasoning is sound! Either H returns true, or false, or loops forever. The first two options can’t be true, on pain of paradox. Leaving only the last possibility. But if we can prove that, so can H. And that itself creates a paradox.

H proves that it can't decide the question one way or the other. The assumption that H can only return TRUE or FALSE is flawed: if a proof exists that something is undecidable, then H would need to be able to return "undecidable".

This example seems to verify the halting problem: you came up with an algorithm that tries to decide whether a program halts, and then came up with an input for which the algorithm can't decide one way or another.

Comment author: JEB_4_PREZ_2016 26 August 2015 10:51:57PM 0 points [-]

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.

Comment author: Epictetus 26 August 2015 11:57:49PM 0 points [-]

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?"

We don't have accurate predictions about what the next 1,000 years are going to look like. Any probability calculation we make will be mostly influenced by our priors; in other words, an optimist would compute a good expected utility while a pessimist would reach the opposite result.

Responses like yours confuse me because they seem to confidently imply that the future will be incredibly boring or something.

I'm saying that if there's nothing impressive about my life in the present or the past, then I'm not one to expect much more out of the future. Some people have a cause or goal and would like to live long enough to see it through--good for them, I say.

I harbor no such vision myself. It's possible that something comes up at a later time and, over the course of 1,000 years (say), it seems rather likely that at some point I'd encounter that feeling. It's equally likely that something unavoidably bad comes up. On balance, I'm indifferent.

Comment author: Epictetus 26 August 2015 08:06:49PM 1 point [-]

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.

Comment author: Epictetus 24 August 2015 12:10:02AM 2 points [-]

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.

In response to comment by Epictetus on 3AM stats quiz
Comment author: gjm 22 August 2015 12:52:46PM *  0 points [-]

Small quibble: +- at the end.

[EDITED to be less spoilery.]

In response to comment by gjm on 3AM stats quiz
Comment author: Epictetus 22 August 2015 12:56:06PM 0 points [-]

Of course. I seem to have overlooked that.

In response to 3AM stats quiz
Comment author: Epictetus 22 August 2015 12:03:07PM 0 points [-]

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.

Comment author: Brillyant 22 August 2015 02:45:11AM *  -1 points [-]

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.

Comment author: Epictetus 22 August 2015 03:55:06AM 0 points [-]

You're conflating weight loss and nutrition throughout.

Short term, the body is resilient enough that you can go on a crash diet to quickly drop a few pounds without worrying about nutrition. On the other hand, nutrition is an essential consideration in any weight-loss plan that's going to last many months. That's why I associate the two.

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.

Certain approaches purport to do this very thing by means of suppressing the appetite so that one naturally eats less. Consider, for example, the Shangri-La diet.

I will grant that if one wants to lose 2+ pounds a week over a long period of time, then the pangs of hunger are unavoidable.

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.

Agreed. This is especially true if there's a psychological component to the initial weight gain. For example, stress eaters will have to either avoid stress or figure out a new coping mechanism if they want to lose weight and maintain the weight loss.

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