Doublethink (Choosing to be Biased)
An oblong slip of newspaper had appeared between O'Brien's fingers. For perhaps five seconds it was within the angle of Winston's vision. It was a photograph, and there was no question of its identity. It was the photograph. It was another copy of the photograph of Jones, Aaronson, and Rutherford at the party function in New York, which he had chanced upon eleven years ago and promptly destroyed. For only an instant it was before his eyes, then it was out of sight again. But he had seen it, unquestionably he had seen it! He made a desperate, agonizing effort to wrench the top half of his body free. It was impossible to move so much as a centimetre in any direction. For the moment he had even forgotten the dial. All he wanted was to hold the photograph in his fingers again, or at least to see it.
'It exists!' he cried.
'No,' said O'Brien.
He stepped across the room.
There was a memory hole in the opposite wall. O'Brien lifted the grating. Unseen, the frail slip of paper was whirling away on the current of warm air; it was vanishing in a flash of flame. O'Brien turned away from the wall.
'Ashes,' he said. 'Not even identifiable ashes. Dust. It does not exist. It never existed.'
'But it did exist! It does exist! It exists in memory. I remember it. You remember it.'
'I do not remember it,' said O'Brien.
Winston's heart sank. That was doublethink. He had a feeling of deadly helplessness. If he could have been certain that O'Brien was lying, it would not have seemed to matter. But it was perfectly possible that O'Brien had really forgotten the photograph. And if so, then already he would have forgotten his denial of remembering it, and forgotten the act of forgetting. How could one be sure that it was simple trickery? Perhaps that lunatic dislocation in the mind could really happen: that was the thought that defeated him.
-- George Orwell, 1984
What if self-deception helps us be happy? What if just running out and overcoming bias will make us - gasp! - unhappy? Surely, true wisdom would be second-order rationality, choosing when to be rational. That way you can decide which cognitive biases should govern you, to maximize your happiness.
Leaving the morality aside, I doubt such a lunatic dislocation in the mind could really happen.
Second-order rationality implies that at some point, you will think to yourself, "And now, I will irrationally believe that I will win the lottery, in order to make myself happy." But we do not have such direct control over our beliefs. You cannot make yourself believe the sky is green by an act of will. You might be able to believe you believed it - though I have just made that more difficult for you by pointing out the difference. (You're welcome!) You might even believe you were happy and self-deceived; but you would not in fact be happy and self-deceived.
For second-order rationality to be genuinely rational, you would first need a good model of reality, to extrapolate the consequences of rationality and irrationality. If you then chose to be first-order irrational, you would need to forget this accurate view. And then forget the act of forgetting. I don't mean to commit the logical fallacy of generalizing from fictional evidence, but I think Orwell did a good job of extrapolating where this path leads.
You can't know the consequences of being biased, until you have already debiased yourself. And then it is too late for self-deception.
The other alternative is to choose blindly to remain biased, without any clear idea of the consequences. This is not second-order rationality. It is willful stupidity.
Be irrationally optimistic about your driving skills, and you will be happily unconcerned where others sweat and fear. You won't have to put up with the inconvenience of a seatbelt. You will be happily unconcerned for a day, a week, a year. Then CRASH, and spend the rest of your life wishing you could scratch the itch in your phantom limb. Or paralyzed from the neck down. Or dead. It's not inevitable, but it's possible; how probable is it? You can't make that tradeoff rationally unless you know your real driving skills, so you can figure out how much danger you're placing yourself in. You can't make that tradeoff rationally unless you know about biases like neglect of probability.
No matter how many days go by in blissful ignorance, it only takes a single mistake to undo a human life, to outweigh every penny you picked up from the railroad tracks of stupidity.
One of chief pieces of advice I give to aspiring rationalists is "Don't try to be clever." And, "Listen to those quiet, nagging doubts." If you don't know, you don't know what you don't know, you don't know how much you don't know, and you don't know how much you needed to know.
There is no second-order rationality. There is only a blind leap into what may or may not be a flaming lava pit. Once you know, it will be too late for blindness.
But people neglect this, because they do not know what they do not know. Unknown unknowns are not available. They do not focus on the blank area on the map, but treat it as if it corresponded to a blank territory. When they consider leaping blindly, they check their memory for dangers, and find no flaming lava pits in the blank map. Why not leap?
Been there. Tried that. Got burned. Don't try to be clever.
I once said to a friend that I suspected the happiness of stupidity was greatly overrated. And she shook her head seriously, and said, "No, it's not; it's really not."
Maybe there are stupid happy people out there. Maybe they are happier than you are. And life isn't fair, and you won't become happier by being jealous of what you can't have. I suspect the vast majority of Overcoming Bias readers could not achieve the "happiness of stupidity" if they tried. That way is closed to you. You can never achieve that degree of ignorance, you cannot forget what you know, you cannot unsee what you see.
The happiness of stupidity is closed to you. You will never have it short of actual brain damage, and maybe not even then. You should wonder, I think, whether the happiness of stupidity is optimal - if it is the most happiness that a human can aspire to - but it matters not. That way is closed to you, if it was ever open.
All that is left to you now, is to aspire to such happiness as a rationalist can achieve. I think it may prove greater, in the end. There are bounded paths and open-ended paths; plateaus on which to laze, and mountains to climb; and if climbing takes more effort, still the mountain rises higher in the end.
Also there is more to life than happiness; and other happinesses than your own may be at stake in your decisions.
But that is moot. By the time you realize you have a choice, there is no choice. You cannot unsee what you see. The other way is closed.
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Comments (38)
PS: See also Scott Aaronson's classic On Self-Delusion and Bounded Rationality.
I am not an island. There are a few good ways to set up a life of bounded bias or a rational decision about whether or not to engage in bias. I am a social creature and as such am acutely aware that most of my decisions are made as a mix of peer pressure, groupthink, discussions with friends, unconscious reasoning and whatever media I may have managed to digest in the past few hours. I have several friends, one of whom is a dedicated rationalist but a genuinely kind person, his name is Steve I have given him these instructions..::please give me unsolicited advice and interrupt me if you see me doing something stupid or immoral but only if you think I could emotionally cope with the reasons why my action was immoral:: I have another friend he's something of a spiritualist and currently some form of wiccan something or other. His name is Dave, also a kind person and he has explicit instructions. ::Please give me unsolicited advice and help me out if I seem to be unhappy Give me the course of action you think would make me happiest so long as it doesn't conflict with what Steve has told me to do. When I have to get a good think on about something I call steve and dave separately, then call them both together, and compare the three suggestions. What is interesting is I have done this often enough that I can often predict what each will say in a sort of mental role taking that is much easier if you imagine it not being you that has such thoughts. As such I have achieved some bounded bias, that is I am biogted enough to not be a social pariah in America (one must be somewhat prejudiced against someone to survive socially even if its only prejudiced against bigots and republicans) But rational enough not to fall for gambler's fallacies and at least bright enough to nod along when a modus ponens is explained to me using small words for the fourteenth time. Its not perfect, but its mine, Most people outsource their morality anyway., from what would jesus do, to local faith leaders to calling their parents for advice. I'm just a little more structured and deliberate. Through this system I can have someone have an unbiased view and speak to someone with a biased view and make a decision as to which is a better view to have without having to unsee everything. Yes I realize steve won't be perfectly unbiased every time or perfectly rational or make the right choices but then again, neither would I and there's nothing special about me making my mistakes.
"believing you're happy" and "in fact happy" strike me as distinctions without distinction. How are they falsifiable?
What if self-deception helps us be happy? What if just running out and overcoming bias will make us - gasp! - unhappy?
You are aware, I'm sure, of studies that connect depression and freedom from bias, notably overconfidence in one's ability to control outcome.
You've already given one answer: to deliberately choose to believe what our best judgement tells us isn't so would be lunacy. Many people are psychologically able to fool themselves subtly, but fewer are able to deliberately, knowingly fool themselves.
Another answer is that even though depression leads to freedom from some biases and illusions, the converse doesn't seem to apply. Overcoming bias doesn't seem to lead to depression. I don't get the impression that a disproportionate number of people on this list are depressed. In my own experience, losing illusions doesn't make me feel depressed. Even if the illusion promised something desirable, I think what I have usually felt was more like intellectual relief, "So that's why (whatever was promised) never seemed to work."
Depression is specifically linked to reducing overconfidence. People more accurately assess their own abilities (and perhaps others' abilities as well). I'm not aware that it's linked to decreasing other biases.
"How happy is the moron: / He doesn't give a damn. / I wish I were a moron. / -- My God, perhaps I am!"
Or, in other words, wanting to be stupid is itself a form of stupidity.
I'm pleased to say that, through a great deal of study and practice, I *have* learned how to unlearn things that I know. This is called skepticism. A key to it is the ability to imagine plausible alternatives to whatever is believed. Descartes is famous for developing this idea, although he was constrained by his society from completely embracing it. Pyrrho and Sextus Empiricus developed this idea, but their community was persecuted and destroyed by the Christians, too.
Skepticism is not opposed to rationality, but neither does it accept that a rationally derived solution to a problem is *necessarily* the best solution (unless you define rationality as whatever leads to the best solution, in which case you have to abandon the notion of a rational methodology).
My wife is an ongoing experiment and example for me, because she seems to live her life almost entirely without rationality and critical thinking as I recognize it. She lives instead by pattern matching and by the process of comparing real and anticipated feelings. You feel superior to her. Well, she feels superior to you. Is there a non-biased process that can decide who is right? Sure there is: mutation and natural selection. My wife is the product of billions of years of evolution, as are you. So, it seems to be a tie...
I like being "smart" and "analytical". It's my kind of game. I find symbolic logic fascinating. I write software using my logical mind. I enjoyed reading your wonderful tutorial on Bayesian reasoning, though I already knew the material, having read the Cartoon Guide to Statistics and the works of Tversky and Kahneman, years ago. But not since 1920 or so has it been possible to make a fully rational case for living a fully rational life. To do that you have to base your reasoning on premises, and that leads to the infinite regress problem. You have to map your premises to reality, but you don't have direct access to reality.
I'm not attacking rationality. I love it. But why be biased in favor of it? Why not just do what works for you and leave it at that?
This thing about depressed people being unbiased makes no sense to me. Maybe they're not overconfident, but aren't they underconfident instead? I'd find it pretty surprising if a mental illness was correlated with common sense.
Anyway, perhaps the key to being rational and happy is suppressing not facts, but fear of them. No, you can't have a pony. Get over it.
Tiiba: "makes no sense" and "would be surprising" are very different things, and the former is excessive for the claim about depressed people. The level of confidence that's optimal for making correct predictions about the world could be much lower than the level that's optimal for living a happy life. Do you have some way of knowing that it isn't?
(Let me forestall one argument against by remarking that evolution is not in the business of maximizing our happiness.)
This post strikes me as being pretty arrogant. Actually the whole blog tends in that direction, but this post especially, where the author finally makes clear the dichotomy between the readers of this blog (the uber-rationalists) and everyone else (the stupid).
When your world view causes you to believe that everyone who is not single-mindedly pursuing your worldview is stupid, I think you should treat that as a warning sign of bias. Even if your world view is about overcoming bias.
Um, there are readers of this blog, and there are people who enjoy the "happiness of stupidity" (which is not the same as just having a low IQ; it involves other personality traits as well). I don't think there's much overlap between those two groups. But they are far from being the only two groups in the world, and there is no dichotomy between them.
My understanding is that happiness is a product of biochemistry and neuroanatomy, and doesn't have to inherently correlate with any knowledge, experience, or heuristic.
Does having an explanatory style personality (ie delusional optimism) lead to reduced rates of depression and increased happiness?
http://www.psych.nyu.edu/oettingen/OETTINGEN1995EXPLANATORY.PDF
"Leaving the morality aside, I doubt such a lunatic dislocation in the mind could really happen."
Have you talked to any religious people lately? "Oh, the tornado ripped my neighbors house off the foundations, but we were spared. I guess God was looking out for us!"
Could anyone say that without willfully blinding themselves? Do they really think they are better people than their neighbors, and that God moved the tornado away from their house? Yet you hear stuff like this all the time. And I think they really believe it.
The ability to delude ourselves seems to be one of our main survival traits. Rational people would never take the stupid chances that result in progress. Evolution has favored a species that buys lottery tickets.
Surely, true wisdom would be second-order rationality, choosing when to be rational. ... You can't know the consequences of being biased, until you have already debiased yourself. And then it is too late for self-deception. The other alternative is to choose blindly to remain biased, without any clear idea of the consequences. This is ... willful stupidity.
This isn't quite fair. While it is true that you couldn't know the detailed consequences of being biased, you could make a rational judgment under uncertainty, given what you do know. And it should be possible to for your best judgment in this situation to be that you are better off biased. Of course this mere possibility does not mean that you are in fact better of being biased.
While it is true that you couldn't know the detailed consequences of being biased, you could make a rational judgment under uncertainty, given what you do know.
Yes, but for it to be a rational judgment under uncertainty, you would have to take into account the unknown unknowns, some of which may be Black Swans (where rare events accounts for a significant fraction of the total weight), plus such well-known biases as overconfidence and optimism. Think of all that worrying you'll have to do... maybe you should just relax...
My own life experience suggests that any black box should be assumed to contain a Black Swan. (Or to be precise, a substantial probability of such, rather than probability 1.0.)
State legitimacy is similarly based on such self deception, whether it uses the traditional "'cos God says so" approach, or the more modern, "'cos we won a popularity contest." idea: in neither circumstance is there any real reason why people in general should act as if the state has the right to make laws and manage people, and yet it does, apparently to the general good unless you happen to be a radical libertarian.
Surely this is the same as the happiness case: by having most people in a nation sharing the delusional belief in the legitimacy of the state, the nation as a whole benefits.
Eliezer, we are in essence talking about a value of info calculation. Yes, such a calculated info value rises with rare important things you might know if you had the info. But even so it is not guaranteed that info will be worth the cost. Similarly, it is not guaranteed that our choosing to avoid bias will be worth the costs.
It seems to me simpler to just say that given our purposes we judge better overcoming our biases to in fact be cost-effective on the topics we emphasize here. The strongest argument for that seems to me that we emphasize topics where our evolved judgments about when we can safely be biased are the least likely to be reliable guides to social, as opposed to personal, value.
...you will think to yourself, "And now, I will irrationally believe that I will win the lottery, in order to make myself happy." But we do not have such direct control over our beliefs. You cannot make yourself believe the sky is green by an act of will.
In my experience, this is not true.
My father was a dentist, and when I was 7 he learned hypnosis to use to anesthetise his patients. Of course he practiced on me while he was learning. (As it turned out, he did successful anesthesia with it for a few years before people started spreading stories that hypnosis was dangerous mind-control and he quit.)
With posthypnotic suggestion people can easily believe things that they have no reason to believe, remember things they did not experience, and ignore their senses up to a point. I've done it. It all feels real.
I learned to hypnotise people a little, and I learned how to do it on myself. It certainly can be done. You do have that control over your beliefs, if you're willing to use it.
Which is not to say it's a good idea. IME the main time it's useful to make yourself believe something is when you have nothing to lose by burning your bridges, when you lose everything anyway if the belief is wrong. Then you might as well believe it wholeheartedly.
I've read that interest in hypnosis has something like an eleven year cycle. People start to think there's something interesting there. They start studying it, and get some fascinating results that look some ways powerful. Then as they keep studying they find that all the unexpected things people can do under hypnosis they can also do without hypnosis. And then they start to see that a lot of people are basicly walking around hypnotised a lot of the time. They start to wonder what exactly they're studying, and they quit, and after the subject lies fallow awhile more people get interested and it starts again.
Basicly all it takes for hypnosis is that the person relax and listen uncritically. If they're willing to believe what they're told, they're hypnotised. All the peculiar abilities people sometimes display when told to under hypnosis, are things they could do but normally don't believe they can do. When they give up their scepticism they go ahead and do their best instead of doubting themselves and hesitating. They're willing to believe delusions for somebody they trust, and when the limits of the trust show up or they get emphatic evidence against the delusion, then they rethink.
You really can deceive yourself. You can build false memories and believe them. You can make the sky look a little green, particularly on a cloudy day, and you can build on that until it looks pretty green -- provided the idea of a green sky doesn't offend you too much. If you believe it's impossible you can't see it. If it's "I didn't know that was even possible, I wonder why it's happening now?" then you can.
These are things that anybody can learn to do. But I mostly agree with your arguments that it is not generally a useful skill. If I get a toothache I don't anesthetise it until after I get my dentist appointment, and if I miss the appointment the pain comes back. Pain is your signal that something is going wrong with your body, and in general it's a bad idea to ignore that.
"Evolution has favored a species that buys lottery tickets."
It's (statistically) bad for the individual but good for the species. Although even buying lottery tickets -or the other natural equivalents is probably deoptimized behavior. I imagine there's some bayesian optimized approach for a species and the spectrum of risk taking its members would engage in. In contrast I suspect our species performs functionally rather than optimally.
Forgive me, Master Eliezer, for I have sinned.
I have come to realize that inside my mind is not merely self-delusion, but a full-blown case of doublethink. There are two mutually exclusive statements that I simutaneously hold to be unquestionably true. Here they are:
1) I should not cause suffering to others. 2) Only my own happiness really matters.
I can even explain this doublethink. I am naturally selfish, but society makes me be good. I could try to believe that only I matter, and do good things only for the show, but that strategy doesn't work for most people. Being good is too complex.
This doublethink creates intresting effects. When I read about context insensitivity, I wondered if that's really a bias, or just apathy masquerading as concern. I'd probably give the same amount to save five birds as I would to save Atlantis from sinking. Both are social acts.
I also wonder about coherent extrapolated volition. What will it find when it extrapolates us? That we all want the whole pie? That we would gladly exterminate everyone else if we could get away with it?
"Evolution has favored a species that buys lottery tickets."
It's (statistically) bad for the individual but good for the species.
This is a group selection argument. (If you don't know what that means, it's something that biologists use to scare their children.) Evolution does not operate on species. It operates on individuals. Genes that are statistically bad for individuals drop out of the gene pool no matter what they do for the species.
This is an ancient and thoroughly discredited idea. See George Williams's "Adaptation and Natural Selection."
Actually, there can be multi-level selection (MLS theory; cf. http://en.wikipedia.org/wiki/Group_selection#Multilevel_selection_theory) when there is competition between groups. In the same sense there is selection between individuals when there is competition between individuals, or the competition between genes popularized by Richard Dawkins.
http://www.americanscientist.org/my_amsci/restricted.aspx?act=pdf&id=16386020847008http://www.americanscientist.org/my_amsci/restricted.aspx?act=pdf&id=16386020847008 is a good primer.
This is the best solution for Darwin's problem of ant colonies, even better than haplodiploidy. I thought I would come out of lurking while reading through the sequences to mention this, since multi-level selection was demonized during the 70s under the name "group selection" due to some overzealous proponents. So, while we would not say "evolution has favored a species that buys lottery tickets", we might hypothesize evolution favors human societies that buy lottery tickets when under competition with other societies that do not (as an example).
Eliezer, I mentioned behaviors/biases that are statistically bad for the individual, not genes. Also, I'm interested in your take on the idea that the existence of humans with a range of different biases can be good for other humans, even if it's not optimal from the perspective of the person with the bias.
"When I read about context insensitivity, I wondered if that's really a bias, or just apathy masquerading as concern. I'd probably give the same amount to save five birds as I would to save Atlantis from sinking. Both are social acts."
I want to clarify. I do believe in context insensitivity, but think indifference was also a factor in the donation case.
Genes that are bad for many of the individuals that carry them but that have large jackpots can be selected. As for how you tell whether the occasional large jackpot makes up for the common failure, it takes a long time to tell.
With lotteries you can judge by the house. They're in business to make money, they have wealth that they got from previous lotteries, it makes sense the odds are against you in the longterm. But that reasoning doesn't work in general.
Human beings who see jackpot events happen will sometimes gamble for long times without winning a jackpot. If they didn't they couldn't win. They lose cumulatively while they wait. It takes as long time to find out by trial and error whether they win on average or not, and if they don't try long enough they don't find out what the odds really are.
Eliezer, do you concede that there is no difference between "believing you're happy" and "really being happy"?
HA, I was surprised you stumbled into that one. A good introductory example of how evolution does not optimize at the species but at the gene-level can be found here. It is by Richard Dawkins, who is also known for the term "meme", which is an idea that can be analyzed like a gene. Unless the meme that buying lottery tickets is a good idea is beneficial for those that hold it, we should not expect it to become prevalent even it if benefits the species. You can find other good posts from Razib on "group selection" if you look for them.
Eliezer, do you concede that there is no difference between "believing you're happy" and "really being happy"?
No. There is a difference between believing you love your stepchildren and loving your stepchildren, between believing you're deeply upset about rainforests and being deeply upset about rainforests, and between believing you're happy and being happy.
As soon as you turn happiness into an obligatory sign of spiritual health, a sign of virtue, people will naturally tend to overestimate their happiness.
Falsifiable difference? Put 'em in an fMRI or use other physiological indicators.
Unless the meme that {buying lottery tickets is a good idea} is beneficial for those that hold it, we should not expect it to become prevalent even it if benefits the species.
But it is prevalent. And on average people lose money at it, while the occasionaly winners tend not to do well.
So it's natural to suppose that the meme for buying lottery tickets is a perversion of some other functional meme.
Here's a way that lotteries could be functional after all for people in extended families. If you sacrifice and save and start to build up a little capital, you may be accosted by distant relatives in need who have the right to your assistance, and it all drains away. But when you win the lottery you can go live in some distant place and only share enough to stay in distant good standing. When building up savings is considered immoral, paying 40% on average might not seem so bad for a chance to get some capital anyway.
"Evolution does not operate on species. It operates on individuals. Genes that are statistically bad for individuals drop out of the gene pool no matter what they do for the species."
Imagine a gene that caused 9/10 of the humans who have it to be twice as fertility and attractiveness as the population that did not have it, while 1/10 of the humans who have it can't reproduce at all. This would be a gene that would serve the species (i.e. the portion of the species that had it), even though it would harm some individuals. Notice that the inability of the 10% to procreate would not harm the prospects of such a gene for the species as a whole. Soon, the whole of the species would have this gene.
Isn't there some theorizing that suggests that homosexuality may be an example of something like this? Perhaps the phenomenon of homosexuality is linked to some wonderful benefit that increases the viability of heterosexuals. Otherwise, wouldn't homosexuals have been "selected out" long ago?
Imagine a gene that caused 9/10 of the humans who have it to be twice as fertility and attractiveness as the population that did not have it, while 1/10 of the humans who have it can't reproduce at all.
this is means that the allele (genetic variant) increase fitness by a factor of 1.8. this is not a "species level" benefit in anything but a tautological way. higher levels of selection or dynamic processes are only interesting if they can not be reduced down to a lower level. e.g., you can increase the fitness of the group by simply increasing the fitness of individuals which compose the group. this increases the fitness of the group, but it is easily reduced toward increasing the fitness of individuals. in other cases you can not decompose the group fitness to individuals and so there is grounds for saying that the excess fitness which is gained by having a group, or evaluating a group, is something that is "for the good of the group."
to use a sports analogy, if you brought together an all-star team you'd get a better team, not because of the team dynamics but because the individual players are so much better. in contrast, ther are teams which are very good because of group dynamics where utility players can specialize in their roles and synergistically perform far better than they might as individuals.
This is an ancient and thoroughly discredited idea. See George Williams's "Adaptation and Natural Selection."
i am generally skeptical of group selectionist arguments, but we are probably on the cusp of a renaissance in this area. it will be spearheaded by e.o. wilson, who has always been a "believer," but who now believes that group selection (or at least multi-level selection) has the empirical and analytical firepower to make a comeback. i am cautiously skeptical, but in the interests of honesty i think that "ancient and thoroughly discredited" is probably a better description for group selection circa 1995 than 2007. most evolutionary biologists are probably pretty skeptical of group selectionist arguments, but in large part it is because the models presented (which tend to avoid the pitfalls of the earlier arguments) are hard to test and seem analytically intractable beyond the simplest formulations.
Imagine a gene that caused 9/10 of the humans who have it to be twice as fertility and attractiveness as the population that did not have it, while 1/10 of the humans who have it can't reproduce at all.
btw. you don't have to imagine. sickle cell is like this. a proportion of the population gets increased benefit from having the gene, and a proportion gets decreased benefit, in the ratio of heterozygotes (those who carry one sickle cell allele and one normal) and homozogytes (those who carry two alleles), i.e., 2pq:q^2. that's not species selection, it's standard balancing selection upon one gene.
What's wrong with group selection? All you need is for the benefit to the individual of being in a group in which trait X is sufficiently common to be sufficiently bigger than the benefit of not having trait X in the individual... or am I confused?
You know, self-deception has attracted some inquiry already.
Doug, what's wrong with group selection is mostly that selection at the individual level works so much faster. If something's harmful to individuals, it's likely to have been wiped out by individual-level selection before it gets the chance to help the group.
It's possible to concoct scenarios where group-level effects win. For instance: some allele has no effect at all when heterozygous, but when homozygous it causes its bearer to become astonishingly altruistic. By the time there's much incidence of homozygosity in any given community, the chances are that the allele is (heterozygously) quite common, and then it's possible that the individual's altruism does more net good than harm to bearers of the allele. This is kin selection rather than group selection really, but on a different scale from the usual.
Or: some allele has a *very slight* deleterious effect on individual fitness in general-- slight enough that it typically takes, say, 100 generations before natural selection becomes visible over genetic drift. If it then has some group-level effect that prevents rare but group-destroying incidents (say, once every 100 generations someone without it will go nuts and kill everyone around them) then it could be selected for on balance simply because groups where it doesn't happen to get fixed in the population tend to die. Note that making this work is rather dependent on group size.
But it's pretty hard to concoct such scenarios that are actually *plausible*, and pretty hard to argue that anything in the real world looks much like them.
Doug S, G has given a good explanation (except possibly the last sentence which is debatable.) I'll explain again: Selection happens when genes increase in frequency compared to other genes. Since genes always happen inside individuals, a gene that causes its individuals to leave fewer offspring in the population will be selected *against*, regardless of what it does for the population as a whole.
A gene that results in good stuff for the population but that doesn't result in its own carriers increasing *more* than others won't increase in the population even though all the individuals in the population would be better off.
You can get by this a little by assuming a population split into breeding groups with limited outbreeding, where a gene that improves the group enough can take over in a small group, and then when the group gets bigger it splits and both groups increase compared to other groups, etc. But too much outbreeding would stop it. Something like this may happen in rats and fruit flies etc, too soon to be sure.
There could be specific genetic mechanisms that provide a system to to create group selection. Diploidy is a peculiar genetic mechanism, as are sexuality and dominance. There could be others that are less obvious, that benefit the populations that let them operate, and group selection is one of the things they might promote. But that's entirely speculative at this point.
James Bach, if something has a frequency above 1% and has high fitness costs to those that hold it, it is probably pathogenic rather than genetic. You can find more on that from Greg Cochran at the bottom of this page.