I would expect the result to be a more accurate estimation of the success, combined with more sign-ups . 2 is an example of this if, in fact, the more accurate assessment is lower than the assessment of someone with a different level of information.

I don't it's true that everyone starts from "that won't ever work" - we know some people think it might work, and we may be inclined to some wishful thinking or susceptability to hype to inflate our likelihood above the conclusion we'd reach if we invest the time to consider the issue in more depth, It's also worth noting that we're not comparing the general public to those who've seriously considered signing up, but the lesswrong population, who are probably a lot more exposed to the idea of cryonics.

I'd agree that it's not what I would have predicted in advance (having no more expectation for the likelihood assigned to go up as down with more research), but it would be predictable for someone proceeding from the premise that the lesswrong community overestimates the likelihood of cryonics success compared to those who have done more research.

The Humans are Special trope here gives a lot of examples of this. Reputedly, it was a premise that John Campbell, editor of Amazing Stories, was very fond of, accounting for its prevalence.

and as such makes bullets an appropriate response to such acts, whereas they were not before.

Ah, I think I've misunderstood you - I thought you were talking about the initiating act (ie. that it was as appropriate to initiate shooting someone as to insult them), whereas you're talking about the response to the act: that bullets are an appropriate response to bullets, therefore if interchangable, they're an appropriate response to speech too. However, I don't think you can take the first part of that as given - many (including me) would disagree that bullets are an appropriate response to bullets, but rather that they're only an appropriate response to the specific case of averting an immediate threat (ie. shoot if it prevents killing, but oppose applying the death penalty once out of danger), and some pacifists may disagree even with violence to prevent other violence.

However, it seems that it's the initiating act that's the issue here: is it any more justified to causing offence as to shoot someone. I think it could be argued that they are equivalent issues, though of lesser intensity (ie. back to continuums, not bright lines).

If they are interchangeable it follows that answering an argument with a bullet may be the efficient solution.

That's clearly not the case. If they're interchangable, it merely means they'd be equally appropriate, but that doesn't say anything about their absolute appropriateness level. If neither are appropriate responses, that's just as interchangable as both being appropriate - and it's clearly that more restrictive route being advocated here (ie. moving such speech into the bullet category, rather than moving the bullet category into the region of such speech).

The brits are feeling the pain of a real physical assault, under the skin.

So what distinguishes that from emotional pain? It's all electrochemistry in the end after all. Would things change if it were extreme emotional torment being inflicted by pictures of salmon, rather than pain receptors being stimulated? Eg. inducing an state equivalent to clinical depression, or the feeling of having been dumped by a loved-one. I don't see an inherent reason to treat these differently - there are occassions where I'd gladly have traded such feelings for a kick in the nuts, so from a utlitarian perspective they seem to be at least as bad.

The intensity in this case is obviously different - offence vs depression is obviously a big difference, so it may be fine to say that one's OK and the other not because it falls into a tolerable level - but that certainly moves away from the notion of a bright line towards a grey continuum.

A crucial difference is that we can change our minds about what offends us but we cannot choose not to respond to electrodes

This is a better argument (indeed it's one brought up by the post). I'm not sure it's entirely valid though, for the reasons Yvain gave there. We can't entirely choose what hurts us without a much better control over our emotional state than I, at least, posess. If I were brought up in a society where this was the ultimate taboo, I don't think I could simply choose not to be, anymore than I could choose to be offended by them now. You say "It is within my power to feel zero pain from anything you might say", but I'll tell you, it's not within mine. That may be a failing, but it's one shared by billions. Further, I'm not sure it would be justified to go around insulting random strangers on the grounds that they can choose to take no harm, which suggests to me that offending is certainly not morally neutral.

Personally, I think one answer we could give to why the situations are different is a more pragmatic one. Accept that causing offence is indeed a bad action, but that it's justified collateral damage in support of a more important goal. Ie. free speech is important enough that we need to establish that even trying to prevent it will be met by an indescriminate backlash doing the exact opposite. (Though there are also pragmatic grounds to oppose this, such that it's manipulable by rabble-rousers for political ends).

Is that justified though? Suppose a subset of British go about demanding restriction on salmon image production. Would that justify you going out of your way to promote the production of such images, making them more likely to be seen by the subset not making such demands?

But the argument here is going the other way - less permissive, not more. The equivalent analogy would be:

To hold that speech is interchangeable with violence is to hold that certain forms of speech are no more an appropriate answer than a bullet.

The issue at stake is why. Why is speech OK, but a punch not? Presumably because one causes physical pain and the other not. So, in Yvain's salmon situation, when such speech does now cause pain should we treat it the same or different from violence? Why or why not? What then about other forms of mental torment, such as emotional pain, hurt feelings or offence? There are times I've had my feelings hurt by mere words that frankly, I'd have gladly exchanged for a kicking, so mere intensity doesn't seem the relevant criteria. So what is, and why is it justified?

To just repeat "violence is different from speech" is to duck the issue, because you haven't answered this why question, which was the whole point of bringing it up.

Newcomb's scenario has the added wrinkle that event B also causes event A

I don't see how. Omega doesn't make the prediction because you made the action - he makes it because he can predict that a person of a particular mental configuration at time T will make decision A at time T+1. If I were to play the part of Omega, I couldn't achieve perfect prediction, but might be able to achieve, say, 90% by studying what people say they will do on blogs about Newcombe's paradox, and performing observation as to what such people actually do (so long as my decision criteria weren't known to the person I was testing).

Am I violating causality by doing this? Clearly not - my prediction is caused by the blog post and my observations, not by the action. The same thing that causes you to say you'd decide one way is also what causes you to act one way. As I get better and better, nothing changes, nor do I see why something would if I am able to simulate you perfectly, achieving 100% accuracy (some degree of determinism is assumed there, but then it's already in the original thought experiment if we assume literally 100% accuracy).

Assuming I'm understanding it correctly, the same would be true for a manipulationist definition. If we can manipulate your mental state, we'd change both the prediction (assuming Omega factors in this manipulation) and the decision, thus your mental state is a cause of both. However if we could manipulate your action without changing the state that causes it in a way that would affect Omega's prediction, our actions would not change the prediction. In practice, this may be impossible (it requires Omega not to factor in our manipulation, which is contradicted by assuming he is a perfect predictor), but in principle it seems valid.

I don't see why Newcombe's paradox breaks causality - it seems more accurate to say that both events are caused by an earlier cause: your predisposition to choose a particular way. Both Omega's prediction and your action are caused by this predisposition, meaning Omega's prediction is merely correlated with, not a cause of, your choice.

It's not actually putting it forth as a conclusion though - it's just a flaw in our wetware that makes us interpret it as such. We could imagine a perfectly rational being who could accurately work out the probability of a particular person having done it, then randomly sample the population (or even work through each one in turn) looking for the killer. Our problem as humans is that once the idea is planted, we overreact to confirming evidence.

Thinking this through a bit more, you're right - this really makes no difference. (And in fact, re-reading my post, my reasoning is rather confused - I think I ended up agreeing with the conclusion while also (incorrectly) disagreeing with the argument.)