Less Wrong is a community blog devoted to refining the art of human rationality. Please visit our About page for more information.

Comment author: James_Miller 31 March 2015 12:47:10AM 2 points [-]

Yes, knowing just a little about Bayesianism can make you less rational.

Comment author: private_messaging 31 March 2015 01:39:29AM *  1 point [-]

It seems to me that knowing only a little (and/or being bad at applied math) is kind of a pre-requisite for the level of enthusiasm involved in the use of it as a movement name. It's exciting to see all those bits of evidence and see yourself one-upping all those classy educated people that are dead set against use of those bits of evidence, or who even seen to use them in the completely wrong way. It's even more fun to do that with friends.

You know about little math, and it makes a huge difference to everything, that's exciting.

Or you spent years studying and/or working and all that math almost never matters - almost any evidence that's not overwhelmingly strong is extremely confounded with what's already been considered and/or with the chain of events bringing something to your attention.

Comment author: James_Miller 30 March 2015 11:29:02PM 2 points [-]

Without looking at evidence I would guess disproportionately so.

Comment author: private_messaging 31 March 2015 12:08:12AM 2 points [-]

Same here. The reason I think so low of the self proclaimed Bayesianism is the sort of thinking where someone sees someone ugly accused and they're like, ha, I am going to be more rational than everyone else today, by ticking my estimate of the guilt up because they're ugly. Completely ignorant that it even makes a difference to the way you should apply Bayes rule that the police and the witnesses and the like had already picked the suspect with this sort of prejudice.

In response to comment by [deleted] on Torture vs. Dust Specks
Comment author: SimonJester23 30 March 2015 10:33:41PM 2 points [-]

It occurred to me to add something to my previous comments about the idea of harm being nonlinear, or something that we compute in multiple dimensions that are not commensurate.

One is that any deontological system of ethics automatically has at least two dimensions. One for general-purpose "utilons," and one for... call them "red flags." As soon as you accumulate even one red flag you are doing something capital-w Wrong in that system of ethics, regardless of the number of utilons you've accumulated.

The main argument justifying this is, of course, that you may think you have found a clever way to accumulate 3^^^3 utilons in exchange for a trivial amount of harm (torture ONLY one scapegoat!)... but the overall weighted average of all human moral reasoning suggests that people who think they've done this are usually wrong. Therefore, best to red-flag such methods, because they usually only sound clever.

Obviously, one may need to take this argument with a grain of salt, or 3^^^3 grains of salt. It depends on how strongly you feel bound to honor conclusions drawn by looking at the weighted average of past human decision-making.


The other observation that occurred to me is unrelated. It is about the idea of harm being nonlinear, which as I noted above is just plain not enough to invalidate the torture/specks argument by itself due to the ability to keep thwacking a nonlinear relationship with bigger numbers until it collapses.

Take as a thought-experiment an alternate Earth where, in the year 1000, population growth has stabilized at an equilibrium level, and will rise back to that equilibrium level in response to sudden population decrease. The equilibrium level is assumed to be stable in and of itself.

Imagine aliens arriving and killing 50% of all humans, chosen apparently at random. Then they wait until the population has returned to equilibrium (say, 150 years) and do it again. Then they repeat the process twice more.

The world population circa 1000 was about 300 million (roughly,) so we estimate that this process would kill 600 million people.

Now consider as an alternative, said aliens simply killing everyone, all at once. 300 million dead.

Which outcome is worse?

If harm is strictly linear, we would expect that one death plus one death is exactly as bad as two deaths. By the same logic, 300 megadeaths is only half as bad as 600 megadeaths, and if we inoculate ourselves against hyperbolic discounting...

Well, the "linear harm" theory smacks into a wall. Because it is very credible to claim that the extinction of the human species is much worse than merely twice as bad as the extinction of exactly half the human species. Many arguments can be presented, and no doubt have been presented on this very site. The first that comes to mind is that human extinction means the loss of all potential future value associated with humans, not just the loss of present value, or even the loss of some portion of the potential future.

We are forced to conclude that there is a "total extinction" term in our calculation of harm, one that rises very rapidly in an 'inflationary' way. And it would do this as the destruction wrought upon humanity reaches and passes a level beyond which the species could not recover- the aliens killing all humans except one is not noticeably better than killing all of them, nor is sparing any population less than a complete breeding population, but once a breeding population is spared, there is a fairly sudden drop in the total quantity of harm.

Now, again, in itself this does not strictly invalidate the Torture/Specks argument. Assuming that the harm associated with human extinction (or torturing one person) is any finite amount that could conceivably be equalled by adding up a finite number of specks in eyes, then by definition there is some "big enough" number of specks that the aliens would rationally decide to wipe out humanity rather than accept that many specks in that many eyes.

But I can't recall a similar argument for nonlinear harm measurement being presented in any of the comments I've sampled, so I wanted to mention it.

But I thought it was interesting and couldn't recall seeing it elsewhere.

Comment author: private_messaging 30 March 2015 11:32:54PM 0 points [-]

I mentioned duplication. That in 3^^^3 people, most have to be exact duplicates of one another birth to death.

In your extinction example, once you have substantially more than the breeding population, extra people duplicate some aspects of your population (ability to breed) which causes you to find it less bad.

The other observation that occurred to me is unrelated. It is about the idea of harm being nonlinear, which as I noted above is just plain not enough to invalidate the torture/specks argument by itself due to the ability to keep thwacking a nonlinear relationship with bigger numbers until it collapses.

Not every non-linear relationship can be thwacked with bigger and bigger numbers...

Comment author: James_Miller 29 March 2015 06:50:08PM 5 points [-]

Working Paper Ugly Criminals "Using data from three waves of Add Health we find that being very attractive reduces a young adult's (ages 18-26) propensity for criminal activity and being unattractive increases it for a number of crimes, ranging from burglary to selling drugs. A variety of tests demonstrate that this result is not because beauty is acting as a proxy for socio-economic status. Being very attractive is also positively associated adult vocabulary test scores, which suggests the possibility that beauty may have an impact on human capital formation. We demonstrate that, especially for females, holding constant current beauty, high school beauty (pre-labor market beauty) has a separate impact on crime, and that high school beauty is correlated with variables that gauge various aspects of high school experience, such as GPA, suspension or having being expelled from school, and problems with teachers."

More generally: Good human traits are almost always positively correlated with most other good human traits.

Comment author: private_messaging 30 March 2015 11:07:27PM *  1 point [-]

But does beauty influence our judgement in accordance with the correlation, or disproportionally so? It may be for example that ugly people are 10% more likely to commit crimes, 200% more likely to be villains in the movies, and 100% more likely to get flagged as suspects by the prosecutor, or get other massive penalty before you even think consciously about it.

Comment author: gwern 30 March 2015 12:09:53AM *  1 point [-]

For someone murdered at home in the dead of night, the dominant probabilities are that either the murderer was invited in or lived there. Roommates merit investigation. If the evidence clears spouses/lovers and close family, then the probability of it being a roommate goes up considerably. Being female is not going to lower the probability enough to eschew a thorough investigation.

You're not disagreeing, but you're failing to consider the numbers here. If, say, a quarter of people are murdered by their roommates, and males are 10x more likely to be killers than females, what's the odds of a female roommate doing it?

Being female is not going to lower the probability enough to eschew a thorough investigation.

A probability like 2.5% is worth following up on if police have no better leads to focus on, but they visibly focused on it way more, and in fact people focused on it way more; consider how many expressed probabilities were higher than that in the LW survey. And consider the implicit probabilities in the faction of the public and the Kirchers baying for Knox's blood.

All consistent with base-rate neglect (of being female).

Comment author: private_messaging 30 March 2015 10:16:34PM *  -1 points [-]

Okay, let's go with your number... let's suppose hypothetically that you aren't beating or otherwise unduly coercing cute girls into saying what you want, and you started with the probability of 2.5%. Then your suspect tells you they were at the house covering their ears not to hear the screams as their big black boss murdered the victim. Now what happens to 2.5%? After you clear the big black boss, what happens?

I don't think you can claim base rate neglect without also claiming police brutality, coercion, and leading the witness (which would be a much bigger problem)

Comment author: ChristianKl 30 March 2015 09:17:29PM 0 points [-]

Well it's a fairly specific type of breaking down, to be accusing other people. There's other ways of breaking down, you know.

Yes, signing a confession would be another typical one. In that case she would have it even worse.

Her being psychopathic would have likely lead to other facts that a well funded persecution could uncover.

Comment author: private_messaging 30 March 2015 10:03:57PM *  1 point [-]

I think it'd be quite strange to claim that confessions don't ever correlate with guilt.

By the way what she did was she claimed she was at the scene of the crime covering her ears as Lumumba murdered Kercher (and no she didn't call the 112 about it or anything). If she as she says was coerced into making such a statement, yeah, that's not evidence of guilt. But if it is as police says it is, do you still think it's not evidence of guilt?

Picture an alternative universe. Bob, an exchange student from Australia, is being questioned as a witness. There's a minor discrepancy: Jake, his friend, withdrew his alibi for the night. Those things happen, you don't really think too much of it, but you have to question Bob. You're somewhat suspicious but not highly so. Without much of a prompt, Bob tells a story of how he was covering his ears as Peter, his boss, was murdering the victim.

Now what do you do with Bob, exactly? Let him go once you clear Peter? Keep him because he's not a cute girl?

Now, we aren't sure that this is how it went. Police claims that this is how it went and Knox claims that she got pretty much beaten into that statement, and it's one word against the other.

Her being psychopathic would have likely lead to other facts that a well funded persecution could uncover.

She's a foreigner, there's no budget for transatlantic flights to figure out if she had been cruel to animals as a child or the like, there's no jurisdiction, and you can't use that sort of stuff in a court anyway.

Comment author: ChristianKl 30 March 2015 09:54:32AM 0 points [-]

Keep in mind also that there's evidence available to prosecution but unavailable to you. Knox claiming that she got slapped during interrogation, and other claims that those present at the interrogation know for certain to be true or not.

Even if the lied that she was slapped, that doesn't suggest that she's guilty. It rather shows that she was under a lot of pressure which is expected. It doesn't make someone a psychopath to break under strong pressure and being accused of murdering your roommate is strong pressure.

Comment author: private_messaging 30 March 2015 09:00:19PM *  1 point [-]

Well it's a fairly specific type of breaking down, to be accusing other people. There's other ways of breaking down, you know. And if her account of interrogation is false, and the police's account is true, that goes well beyond the lie about slapping. She said she was at the scene of the crime covering her ears as black owner of the bar she works at was murdering the victim, and if you know you didn't coerce the witness into making such a statement, that's very different from coercing a witness into such a statement.

While perhaps insufficient evidence in the court of law, the prosecutor is not the court of law, the prosecutor merely needs a strong suspicion for it to be their job to try to convict.

Ultimately we have Knox's words against the police's, and both sides have a coherent story that makes either side right.

Comment author: Vive-ut-Vivas 30 March 2015 04:19:45PM 2 points [-]

If she only did that once in many hundred days, on that night in particular, then that could be a very huge amount of evidence.

....No. Not even slightly. This line of questioning MIGHT be relevant if you didn't already have the killer identified, with overwhelming physical evidence pointing towards them. You don't need to explain why Knox turned her phone off, because you already have the killer and every single piece of physical evidence at the crime scene accounted for.

Comment author: private_messaging 30 March 2015 08:21:14PM 0 points [-]

Well, for what it's worth their wounds and bruises guy didn't think it was a single killer. And when someone's murdered at their own place in the dead middle of the night, often the cohabitants are involved.

Comment author: private_messaging 30 March 2015 07:42:51AM *  0 points [-]

An interesting piece of easily quantifiable Bayesian evidence could be phones being switched off overnight (dropping off the network) - how often did Knox do that? If she only did that once in many hundred days, on that night in particular, then that could be a very huge amount of evidence. Or she may have done that few times a week, in which case it's irrelevant.

Comment author: komponisto 29 March 2015 07:56:20PM 8 points [-]

The thing that puzzles me here is why Knox was ever prosecuted at all. The prosecution had Guede.

The answer is simple and banal: they didn't get Guede until after they had already decided Knox and Sollecito were guilty. Not prosecuting Knox and Sollecito would have required them not only revise to previous beliefs in which they had become psychologically invested, but also to retract previous public pronouncements -- in short, to admit they had been wrong.

From the inside of their minds, no doubt, Knox and Sollecito just felt so suspicious, in the early days of the case before the physical evidence came in and they were relying on behavior to form hypotheses . It's also likely that they were irrationally angry at Knox because of the false implication of Patrick Lumumba that they coerced out of her, and that this anger and frustration at the failure of their own hypothesis morphed into a sense that Knox was an evil vixen.

Comment author: private_messaging 30 March 2015 05:22:19AM *  -2 points [-]

I think you skip some details. Sollecito withdrew his alibi for Knox. Then Knox implicated Lumumba. And they really go after the guy. Interestingly they fail to railroad Lumumba in the way in which you think they railroaded Knox. Which to me is really interesting because it doesn't fit the 'evil police' story.

Knox of course claims it was extremely coercive, took hours, and some physical abuse from the police. Police denies abuse. We can't really tell either way, but prosecution ought to know how coercive they were. So that's another opportunity to really piss prosecution off.

edit: another thing, wounds and bruises on the body were interpreted as Kercher having been held by one person and stabbed by another. This is the reason why prosecution got so completely sure that more than one person was involved. Yeah, it's rather subjective and unreliable but people can be very sure in that sort of stuff.

There's all sorts of complicated details that are completely missing from the US coverage of the trials, which make the prosecution's position much more understandable. Perhaps the prosecution did not have sufficient evidence, but neither did the prosecution come up with some batshit insane theory out of the blue for no reason when they had everything explained with Guede.

edit: also, Guede was not some random robber, he knew people downstairs and met Knox before at least briefly. If he was random robber who never set his foot on the premises, then Bayesian wise it would have been a no-brainer: it's just unlikely that two independent groups of people who had no chance to pick eachother would be on board with murdering.

View more: Next