I agree with previous comments about publishing in journals being an important status issue, but I think there is other value as well which is being ignored. For all of its annoyances and flaws, one good thing about peer review is that it really makes your paper better. When you submit a pretty good paper to a journal and get back the "revise and resubmit" along with the detailed list of criticisms and suggestions, then by the time the paper actually makes it into the journal, chances are that it will have become a really good paper.

But to return to the issue of papers being taken more seriously when published in a journal, I think that this view is actually quite justified. For researchers who are not already very knowledgeable in the precise area that is the topic for a given paper, whether or not the paper has withstood peer review is a very useful heuristic cue toward how much weight you should place on it. Basically, peer review keeps the author honest. An author posting a paper on his website can say pretty much whatever he wants. One of the purposes of peer reviewers is to make sure that the author isn't making unreasonable claims, mischaracterizing theoretical positions, "reviewing" the relevant previous literature in a grossly selective way, etc. Like I said, if someone is already very familiar with the area, then they can evaluate these aspects of the paper for themselves. But if you'd like to communicate your position to a wider academic audience, peer review can help carry your paper a longer way.

I got to shadow some breast physicians last month, and although it's sort of off topic I think I gained some insight as to why so many doctors get this question wrong.

Which is because it's very different from any situation they ever come across in clinical practice. Guidelines are to screen people with mammography and examination; anyone who comes up as suspicious on those two tests then gets a biopsy. No one gets diagnosed with breast cancer from a mammogram alone, the progression from mammogram on to the next step is hard-coded into a pre-determined algorithm, and so the question of "This woman got a positive on the mammogram; does she have cancer?" never comes up. A question that does come up a lot is a woman panicking because she got a positive mammogram and demanding to know whether she has breast cancer, and the inevitable answer is "We'll need to do more tests, but don't worry too much yet because most of these things are false positives."

So the doctors involved know that most real mammogram results are false positives, they know how to diagnose breast cancer based on the combination of tests they actually do, they just can't do Bayesian math problems when given probabilities. This is kind of interesting if you're curious about their intelligence but as far as I know doesn't really affect clinical care.

Yes, we will have gotten somewhere. This issue is my primary criticism of Popperian epistemology.

OK then :-) Should we go somewhere else to discuss, rather than heavily nested comments? Would a new discussion topic page be the right place?

Is that basically right?

That is the general idea (but incomplete).

The reason we behave as if it's true is that it's the best option available. All the other theories are criticized (= we have an explanation of what we think is a mistake/flaw in them). We wouldn't want to act on an idea that we (thought we) saw a mistake in, over one we don't think we see any mistake with -- we should use what (fallible) knowledge we have.

A justification is a reason a conjecture is good. Popperian epistemology basically has no such thing. There are no positive arguments, only negative. What we have instead of positive arguments is explanations. These are to help people understand an idea (what it says, what problem it is intended to solve, how it solves it, why they might like it, etc...), but they do not justify the theory, they play an advisory role (also note: they pretty much are the theory, they are the content that we care about in general).

One reason that not being criticized isn't a justification is that saying it is gets you a regress problem. So let's not say that! The other reason is: what would that be adding as compared with not saying it? It's not helpful (and if you give specific details/claims of how it is helpful, which are in line with the justificationist tradition, then I can give you specific criticisms of those).

Terminology isn't terribly important. David Deutsch used the word justification in his explanation of this in the dialog chapter of The Fabric of Reality (highly recommended). I don't like to use it. But the important thing is not to mean anything that causes a regress problem, or to expect justification to come from authority, or various other mistakes. If you want to take the Popperian conception of a good theory and label it "justified" it doesn't matter so much.

When you have exactly one non-refuted theory, you go with that.

The other cases are more complicated and difficult to understand.

Suppose I gave you the answer to the other cases, and we talked about it enough for you to understand it. What would you change your mind about? What would you concede?

If i convinced you of this one single issue (that there is a method for making the decision), would you follow up with a thousand other objections to Popperian epistemology, or would we have gotten somewhere?

If you have lots of other objections you are interested in, I would suggest you just accept for now that we have a method and focus on the other issues first.

[option 1] since there is no such thing as confirmation, it turns out that no conjecture is better or worse than any other.

But some are criticized and some aren't.

[option 2] conjecture that best weathered the criticisms you were able to muster

But how is that to be judged?

No, we always go with uncriticized ideas (which may be close variants of ideas that were criticized). Even the terminology is very tricky here -- the English language is not well adapted to expressing these ideas. (In particular, the concept "uncriticized" is a very substantive one with a lot of meaning, and the word for it may be misleading, but other words are even worse. And the straightforward meaning is OK for present purposes, but may be problematic in future discussion.).

Or is it something radically different from these two altogether?

Yes, different. Both of these are justificationist ways of thinking. They consider how much justification each theory has. The first one rejects a standard source of justification, does not replace it, and ends up stuck. The second one replaces it, and ends up, as you say, reasonably similar to Bayesianism. It still uses the same basic method of tallying up how much of some good thing (which we call justification) each theory has, and then judging by what has the most.

Popperian epistemology does not justify. It uses criticism for a different purpose: a criticism is an explanation of a mistake. By finding mistakes, and explaining what the mistakes are, and conjecturing better ideas which we think won't have those mistakes, we learn and improve our knowledge.

Could you explain how a Popperian disputes such an assertion? [(50% probability of humanity surviving the next century)]

e.g. by pointing out that whether we do or don't survive depends on human choices, which in turn depends on human knowledge. And the growth of knowledge is not predictable (exactly or probabilistically). If we knew its contents and effects now, we would already have that knowledge. So this is not prediction but prophecy. And prophecy has build in bias towards pessimism: because we can't make predictions about future knowledge, prophets in general make predictions that disregard future knowledge. These are explanatory, philosophical arguments which do not rely on evidence (that is appropriate because it is not a scientific or empirical mistake being criticized). No corresponding calculation is made at all.

You ask about how Popperians make decisions if not with such calculations. Well, say we want to decide if we should build a lot more nuclear power plants. This could be taken as gambling with a lot of lives, and maybe even all of them. Of course, not doing it could also be taken as a way of gambling with lives. There's no way to never face any potential dangers. So, how do Popperians decide? They conjecture an answer, e.g. "yes". Actually, they make many conjectures, e.g. also "no". Then they criticize the conjectures, and make more conjectures. So for example I would criticize "yes" for not providing enough explanatory detail about why it's a good idea. Thus "yes" would be rejected, but a variant of it like "yes, because nuclear power plants are safe, clean, and efficient, and all the criticisms of them are from silly luddites" would be better. If I didn't understand all the references to longer arguments being made there, I would criticize it and ask for the details. Meanwhile the "no" answer and its variants will get refuted by criticism. Sometimes entire infinite categories of conjectures will be refuted by a criticism, e.g. the anti-nuclear people might start arguing with conspiracy theories. By providing a general purpose argument against all conspiracy theories, I could deal with all their arguments of that type. Does this illustrate the general idea for you?

You seem to be arguing that Bayesianism is wrong, which is a very different thing.

I think it's wrong as an epistemology. For example because induction is wrong, and the notion of positive support is wrong. Of course Bayes' theorem is correct, and various math you guys have done is correct. I keep getting conflicting statements from people about whether Bayesianism conflicts with Popperism or not, and I don't want to speak for you guys, nor do I want to discourage anyone from finding the shared ideas or discourage them from learning from both.

Would you never take a bet?

Bets are made on events, like which team wins a sports game. Probabilities are fine for events. Probabilities of the truth of theories is problematic (b/c e.g. there is no way to make them non-arbitrary). And it's not something a fallibilist can bet on because he accepts we never know the final truth for sure, so how are we to set up a decision procedure that decides who won the bet?

Would never take an action that could possibly be bad and could possibly be good, which requires weighing two uncertain outcomes?

We are not afraid of uncertainty. Popperian epistemology is fallibilist. It rejects certainty. Life is always uncertain. That does not imply probability is the right way to approach all types of uncertainty.

This brings me back to my initial query: give a specific case where Popperian reasoning diverges from Bayesian reasoning, explain why they diverge, and explain why Bayesianism is wrong. Explain why Bayesian's willingness to bet does harm. Explain why Bayesians are slower than Popperians at coming to the same conclusion. Whatever you want.

Bayesian reasoning diverges when it says that ideas can be positively supported. We diverge because Popper questioned the concept of positive support, as I posted in the original text on this page, and which no one has answered yet. The criticism of positive support begins by considering what it is (you tell me) and how it differs from consistency (you tell me).

I think this has at least some truth to it. Keep in mind that there is an IRC channel, though I am not sure how much it gets used. I would endorse the creation of subreddit for rationalists (which would encourage all manner of offtopic discussions) as opposed to a subreddit for discussion of rationality.

Two corrections: I think you mean 'bonding' in the title, and I think you mean 'price' not 'prise' in the 2nd to last paragraph.

we hate not having outgroups because they serve so well to help reassure us in our ingroup values.

This hypothesis would explain outgroup/ingroup activity only in contexts where there are associated values. That doesn't fit in the example in question.

If our situation controls our behavior (let's try to bracket "to what extent" and "how" it does so), then wouldn't it also control what kind of situation we will go for?

Here's an example from an Orwell essay: "A man may take to drink because he feels himself to be a failure, and then fail all the more completely because he drinks."

And then I've always wondered about the following: If situationism is true, why do the folk have such a robust theory of character traits? Can we provide an error theory for why people have such a theory?

Note that the folk do seem to allow for some 'situationism' - for example, when someone gets drunk, we admit they'll have a different persona and some more than others.

Wikipedia has a page on Just-world phenomenon which lists the following references:

Lerner, M, & Simmons, CH. (1966). Observer reaction to the 'innocent victim': Compassion or rejection? Journal of Personality and Social Psychology 4 (2): 203–210.

Carli, L.L. (1999). Cognitive reconstruction, hindsight, and reactions to victims and perpetrators. Personality and Social Psychology Bulletin, 25, 966-979.

Lerner, M.J. & Miller, D.T. (1978). Just world research and the attribution process: Looking back and ahead. Psychological Bulletin, 85, 1030-1051.

I bet that a "related articles" search on ISI Web of Science for the Carli 1999 article will turn up some additional relevant, and hopefully more recent, papers.

Edit: Some additional references from Wiki page on Victim blaming

Janoffbulman, R. (1985). Cognitive biases in blaming the victim. Journal of Experimental Social Psychology 21: 161–178.

Maes, Jürgen (1994). Blaming the victim: Belief in control or belief in justice? Social Justice Research 7: 69–90.

McCaul, K. D.; Veltum, L. G.; Boyechko, V.; Crawford, J. J. (1990). Understanding Attributions of Victim Blame for Rape: Sex, Violence, and Foreseeability. Journal of Applied Social Psychology 20: 1–26.

I don't want to address the introductory scenario much, but there's debate about what the IAT actually predicts.