Epictetus

Karma: 956

Epictetus 19 Sep 2015 20:00 UTC
3 points
on: Why Don’t Rationalists Win?
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.

Epictetus 27 Aug 2015 2:19 UTC
0 points
in reply to: Houshalter’s comment on: Open Thread—Aug 24 - Aug 30
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.

Epictetus 27 Aug 2015 2:04 UTC
1 point
in reply to: [deleted]’s comment on: Open Thread—Aug 24 - Aug 30

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.

Epictetus 27 Aug 2015 1:33 UTC
0 points
in reply to: Houshalter’s comment on: Open Thread—Aug 24 - Aug 30
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.

Epictetus 26 Aug 2015 23:57 UTC
0 points
in reply to: JEB_4_PREZ_2016’s comment on: Why people want to die

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.

Epictetus 26 Aug 2015 20:06 UTC
1 point
on: Why people want to die
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.

Epictetus 24 Aug 2015 0:10 UTC
3 points
on: Self-confidence and status
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.

Epictetus 22 Aug 2015 12:56 UTC
0 points
in reply to: gjm’s comment on: 3AM stats quiz
Of course. I seem to have overlooked that.

Epictetus 22 Aug 2015 12:03 UTC
0 points
on: 3AM stats quiz
Used rot13 to avoid spoilers:

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

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

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.

Epictetus 22 Aug 2015 3:55 UTC
0 points
in reply to: Brillyant’s comment on: Open thread, Aug. 17 - Aug. 23, 2015

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.

Epictetus 22 Aug 2015 1:22 UTC
4 points
in reply to: Brillyant’s comment on: Open thread, Aug. 17 - Aug. 23, 2015

Naive calorie restriction is just regular calorie restriction with a negative name. Good eating habits entail calorie control. That’s not naive. It’s basic.

By “naive” I just mean calorie restriction without any other consideration. For example, a diet where one replaces a large pizza, a 2-Liter bottle of Coca-Cola, and a slice of chocolate cake with half a large pizza,1 Liter of Coca-Cola, and a smaller slice of chocolate cake is what I’d consider naive calorie restriction. I don’t know that anyone would seriously argue that the restricted version even remotely resembles good eating habits.

Lest you accuse me of straw-manning, let it be noted that many obese people subsist on a diet consisting of fast food and junk food. In fact, malnutrition is a very real problem among the obese. That’s right: you can eat 5k+ Calories a day and still exhibit signs of malnutrition if all you eat is junk. When I speak of instilling good eating habits, I have in mind people who exhibit severe ignorance or misconception of basic nutrition.

Avoiding carbs is a good one becuase it will autmotically eliminate 25-60% of an individual’s daily calorie consumption. That’s all it will do.

A low-carb diet is not just a matter of eating what you normally eat, minus the carbohydrates. That’s going to end about as well as a vegetarian diet where you simply cut out the meat from your normal diet. You run into a micronutrient deficiency that can end up causing problems if the new diet is sustained for several months.

Yeah, but strawman. Dieting involves some hunger. It’s not going to kill you. It’s just part of the adjustment to a more healthy level of consumption.

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. That’s why people care about the glycemic index. I have tried losing weight several times over the last seven years or so. There are diets where you feel satisfied most of the time, then there are diets where you finish a meal feeling as hungry as you did when you started. The psychological difference between the two is quite profound and hardly warrants the charge of “strawman”.

Epictetus 21 Aug 2015 14:01 UTC
1 point
in reply to: Regex’s comment on: 0 And 1 Are Not Probabilities

The very idea that 1 may be not-quite-certain is more than a little baffling, and I suspect is the heart of the issue.

If 1 isn’t quite certain then neither is 0 (if something happens with probability 1, then the probability of it not happening is 0). It’s one of those things that pops up when dealing with infinity.

It’s best illustrated with an example. Let’s say we play a game where we flip a coin and I pay you $1 if it’s heads and you pay me $1 if it’s tails. With probability 1, one of us will eventually go broke (see Gambler’s ruin). It’s easy think of a sequence of coin flips where this never happens; for example, if heads and tails alternated. The theory holds that such a sequence occurs with probability 0. Yet this does not make it impossible.

It can be thought of as the result of a limiting process. If I looked at sequences of N of coin flips, counted the ones where no one went broke and divided this by the total number of possible sequences, then as I let N go to infinity this ratio would go to zero. This event occupies an region with area 0 in the sample space.

Epictetus 21 Aug 2015 7:23 UTC
3 points
in reply to: Brillyant’s comment on: Open thread, Aug. 17 - Aug. 23, 2015

The reason low carb diets lead to weight loss is because they restrict calories. I’m aware of many dieting tricks that can assist, but a calorie deficit must be created in order for weight to be lost.

No one in this thread is disputing that you need a calorie deficit to lose weight. My contention is that this is merely the beginning, not the end. Let’s refer to the following passage from the linked article:

Translation of our results to real-world weight-loss diets for treatment of obesity is limited since the experimental design and model simulations relied on strict control of food intake, which is unrealistic in free-living individuals.

A diet should be realistic for free-living individuals. An obese person who wants to lose 50+ lb. could expect to be at it for the better part of a year. A diet that leaves you hungry all day is doomed to fail: it’s unrealistic to expect pure willpower to last that long. That is the point of my post about hunger control. Disregarding it or dismissing it as a mere trick is to ignore that a very important part of dieting is making sure the dieter sticks to the diet.

My point was to specifically disparage diets like the Atkins Diet. It does nothing apart from restricting calories, yet libraries have been written about the magic of how and why it works. It’s all just noise aimed at selling books, etc. to people who are looking for help.

Quite the contrary. The Atkins Diet is not just about losing the weight. It also includes a plan to keep it off. Maintaining weight loss is generally harder than losing the weight in the first place. Yo-yo dieting) is a very real problem. The problem with naive calorie restriction is that it doesn’t instill good eating habits that can be maintained once the weight-loss period ends. The Atkins Diet addresses this and is designed to ease one into eating habits that will maintain the weight loss.

Epictetus 20 Aug 2015 17:14 UTC
1 point
in reply to: Brillyant’s comment on: Open thread, Aug. 17 - Aug. 23, 2015
Hunger is the big diet killer. It’s very hard to maintain a diet if you walk around hungry all day and eat meals that fail to sate your appetite. Losing weight is a lot easier once you find a way to manage your hunger. One of the strengths of the low-carb diet is that fat and protein are a lot better than carbs at curbing hunger.

Epictetus 20 Aug 2015 16:28 UTC
4 points
on: How to fix academia?

So how to solve the problem of scientific misconduct? I don’t have any good answers. I can think of things like “Stop awarding people for mere number of publications” and “Gauge the actual impact of science rather than empty metrics like number of citations or impact factor.” But I can’t think of any good way to do these things. Some alternatives—like using, for instance, social media to gauge the importance of a scientific discovery—would almost certainly lead to a worse situation than we have now.

If you go up the administration, at some point you reach someone who simply isn’t equipped to evaluate a scientist’s work. This may even just be the department head not being familiar with some subfield. Or it might be the Dean, trying to evaluate the relative merits of a physicist and a chemist. It’s the rare person who knows enough about both fields to render good judgment. That’s where metrics come in. It’s a lot easier if you can point to some number as the basis for a decision. Even if it’s agreed that number of publications or impact factor aren’t good numbers to use, they’re still convenient.

Epictetus 20 Aug 2015 14:30 UTC
1 point
in reply to: Regex’s comment on: 0 And 1 Are Not Probabilities

Situations where an event will definitely or definitely not occur doesn’t seem to be consistent with the idea of randomness which I’ve understood probability to revolve around.

“Event” is a very broad notion. Let’s say, for example, that I roll two dice. The sample space is just a collection of pairs (a, b) where “a” is what die 1 shows and “b” is what die 2 shows. An event is any sub-collection of the sample space. So, the event that the numbers sum to 7 is the collection of all such pairs where a + b = 7. The probability of this event is simply the fraction of the sample space it occupies.

If I rolled eight dice, then they’ll never sum to seven and I say that that event occurs with probability 0. If I secretly rolled an unknown number of dice, you could reasonably ask me the probability that they sum to seven. If I answer “0”, that just means that I rolled more than one and fewer than eight dice. It doesn’t make the process less random nor the question less reasonable.

If you treat an event as some question you can ask about the result of a random process, then 1 and 0 make a lot more sense as probabilities.

For the mathematical theory of probability, there are plenty of technical reasons why you want to retain 1 and 0 as probabilities (and once you get into continuous distributions, it turns out that probability 1 just means “almost certain”).

Epictetus 18 Aug 2015 14:30 UTC
3 points
on: The Allais Paradox
Would I pay $24k to play a game where I had a ³³⁄₃₄ probability of winning an extra $3k? Let’s consult our good friend the Kelly Criterion.

We have a bet that pays 1/8:1 with a ³³⁄₃₄ probability of winning, so Kelly suggests staking ~73.5% of my bankroll on the bet. This means I’d have to have an extra ~$8.7k I’m willing to gamble with in order to choose 1b. If I’m risk-averse and prefer a fractional Kelly scheme, I’d need to start with ~$20k for a three-fourths Kelly bet and ~$41k for a one-half Kelly bet. Since I don’t have that kind of money lying around, I choose 1a.

In case 2, we come across the interesting question of how to analyze the costs and benefits of trading 2a for 2b. In other words, if I had a voucher to play 2a, when would I be willing to trade it for a voucher to play 2b? Unfortunately, I’m not experienced with such analyses. Qualitatively, it appears that if money is tight then one would prefer 2a for the greater chance of winning, while someone with a bigger bankroll would want the better returns on 2b. So, there’s some amount of wealth where you begin to prefer 2b over 2a. I don’t find it obvious that this should be the same as the boundary between 1a and 1b.

This is a problem because the 2s are equal to a one-third chance of playing the 1s. That is, 2A is equivalent to playing gamble 1A with 34% probability, and 2B is equivalent to playing 1B with 34% probability.

Equivalence is tricky business. If we look at the winnings distribution over several trials, the 1s look very different from the 2s and it’s not just a matter of scale. The distributions corresponding to the 2s are much more diffuse.

Surely, the certainty of having $24,000 should count for something. You can feel the difference, right? The solid reassurance?

A certain bet has zero volatility. Since much of the theory of gambling has to do with managing volatility, I’d say certainty counts for a lot.

Epictetus 8 Jul 2015 23:46 UTC
1 point
in reply to: gjm’s comment on: Two Cult Koans

(3) Having agreed to do something silly (like wearing a uniform) may put you in a frame of mind where you’re more likely to agree to other silly things the leader of the group asks you to do later.

Why are uniforms necessarily silly? Let’s take military dress uniforms. In the US, you can tell a military member’s rank and branch of service, and even get an idea of their service record, just by looking at their dress uniform. To insiders, this can be rapidly gleaned looking at someone from across a room. With millions of members, individuals cannot possibly be expected to know everybody else and so the uniform serves a useful function.

Epictetus 7 Jul 2015 6:09 UTC
6 points
on: Open Thread, Jul. 6 - Jul. 12, 2015
Recently came across Valiant’s A Theory of the Learnable. Basically, it covers a method of machine learning in the following way: if there’s a collection of objects which either possess some property P or do not, then you can teach a machine to recognize this with arbitrarily small error simply by presenting it with randomly selected objects and saying whether they possess P. The learner may give false positives, but will not give a false negative. Perhaps the following passage best illustrates the concept:

Consider a world containing robots and elephants. Suppose that one of the robots has discovered a recognition algorithm for elephants that can be meaningfully expressed in k-conjunctive normal form. Our Theorem A implies that this robot can communicate its algorithm to the rest of the robot population by simply exclaiming “elephant” whenever one appears.

The mathematics are done in terms of Boolean functions and “k-conjunctive normal form” is a certain technical condition.

What struck me was that the learning could take place without the learner knowing the definition of the concept to be learned. That a thing could be identified with probability arbitrarily close to 1 without the learner necessarily being able to formulate a definition. I was reminded of the judge who said that he could not define pornography, but he knew it when he saw it. There are plenty of other concepts I can think of where identification is easy (most of the time at least) but which defy precise definition.

I’m usually wary of applying scientific results to philosophy, especially where I’m not an expert. Any expert input on whether this is a fair interpretation of the subject would be appreciated.

Epictetus 2 Jul 2015 21:10 UTC
3 points
in reply to: gwern’s comment on: Rationality Quotes Thread June 2015
High fructose corn syrup and its ilk have been rather devastating.