My folks raised us in borderline-fundamentalist Christianity, which made the Santa myth nearly as much of a non-starter as I expect it was for those commenters who were raised Orthodox Jewish.

If and when I have children of my own, I intend to use the Santa myth as an exercise in invisible-dragon baiting, nothing more.

I don't think that argument is even valid. After all, I have the option of putting a human in a box. If I do, one hypothesis states that the human will be tortured and then killed. The other hypothesis states that the human will "vanish"; it's not precisely clear what "vanish" means here, but I'm going to assume that since this state is supposed to be identical in my experience to the state in the first hypothesis, the human will no longer exist. (Alternative explanations, such as the human being transported to another universe which I can never reach, are even more outlandish.)

In either case, I am permanently removing a human from our society. On that basis alone, in the absence of more specific information, I choose not to take this option.

I think you will have to come up with a scenario where 'the action coupled with the more complicated explanation' is more attractive than both 'the action with the simpler explanation' and 'no action' in order to make this argument.

Inklesspen, I also believe in respecting the guy's autonomy. But it sounds like he might be willing to listen to someone who accepts the possible validity of his negative feelings and treats those feelings with respect.

The best reason for going on living is simply to see what happens next. Tell your friend to find and watch the video "Little Miss Sunshine". Suggest that suicide might make sense, but then so might taking anti-depressant medication. But if he wants to try both, he has to do it in the right order. Shift him from talking about suicide to joking about suicide.

But, as I've already said, there are people who can give better advice than mine. Find out what they say.

I have a friend who suffers from severe depression. He has stated on many occasions that he hates himself and wants to commit suicide, but he can't go through with it because even that would be accomplishing something and he can't accomplish anything. [...] To the best of my knowledge he has been seeing therapists and psychologists and they have been unable to help him. How should a rationalist deal with such a situation?

That is very serious business, and it is not likely that you can handle it yourself. The first thing to do is make sure he's seeing a competent therapist. If he's lapsed, or his therapist is actually a quack, or his therapist for some reason doesn't know what's going on, that could be very dangerous. So get a name, contact him or her, and pass along what you just said. In writing. That is the most important thing.

(EDIT: Actually, this is probably too slow; the time it'd take to do what the previous paragraph describes is a substantial unnecessary risk. Contact a suicide prevention hotline first, as Perplexed says.)

He has a firm delusion that he cannot do anything worthwhile, that the world is going to hell in a handbasket and nothing can possibly be done by anyone about it, and everyone else feels the same way he does, but is repressing it.

The cause of this is probably biochemical, and must be addressed at that level. Unfortunately, identifying the cause of this sort of thing is hard, and there are no good tools for it. I would start by checking the basics of his therapists' work - diet (especially micronutrients; ask if he takes a multivitamin), a minimum amount of regular exercise (pressure him into playing a sport with you if necessary), and a minimum amount of recurring social contact (weekly events that happen automatically without him having to do anything to arrange them).

After that, start looking at pharmaceutical solutions. Don't encourage him to change anything without the approval of a licensed professional, since if he's already borderline suicidal then the wrong change could tip him over the edge; but do find out what he's taking, look it up on PubMed, and ask a psychologist other than the one he's currently seeing whether his regimen is reasonable. Whatever it is, your description suggests that either he's not taking it, it's not working, or it's making things worse. You can probably distinguish between the first and the other two possibilities, but not between the second and third. That information would be useful to his therapist; but beware that it could be both that he's not taking it and that it doesn't work, in which case letting his therapist blame the problem on non-compliance could be a problem.

he has been seeing therapists and psychologists and they have been unable to help him.

As you probably already know, therapists and psychologists generally cannot prescribe anti-depressants - that takes an MD (psychiatrist). I am not a psychiatrist, nor do I play one on the internet. I have no idea whether the cause of your friend's depression is biological or purely psychological. I have no idea whether his therapists have advised him to see a psychiatrist, or whether they are the kind of quacks who "don't buy into the biological model". So I don't have the information I think I need, and I don't even know enough about depression to know what information I do need to help you and your friend.

How should a rationalist deal with such a situation?

If I were in your shoes, I would call the local suicide prevention hotline. Tell them the story. They can give you good advice, which may include referring you to even better resources. Do it now. Those hotlines are open 24hrs, and the people (volunteers) who man them know what they are doing much more than I do.

Are we talking about nihilism here or depression?

Nihilism is a philosophical position.

Depression is a mood - a physiological state which causes a psychological state.

Nihilism is sometimes offered by depressed people as a rationalization/justification of their behavior. It is an effect, not a cause.

Chronic depression can be treated pharmaceutically. Episodes of depression often respond to physical activity. Running is a good suggestion for some people.

Nihilism, as a philosophical position, can be treated by reading better philosophy. However, treating nihilism does nothing to cure depression.

Interesting, but the pessimist in me is noting "even a stopped clock is right twice a day".

For every one study like this, there's hundreds of parents yelling that they noticed their kids developed autism right after getting vaccinated, or that they're sure the power lines near their house are affecting their kids' growth, or some other such nonsense.

I think you need to be far less general; not every parent is an expert on their child's behavior, let alone their child's health.

I think the best definition of consciousness I've come across is Hofstadter's, which is something like "when you are thinking, you can think about the fact that you're thinking, and incorporate that into your conclusions. You can dive down the rabbit hole of meta-thinking as many times as you like." Even there, though, it's hard to tell if it's a verb, a noun, or something else.

If we want to talk about it in computing terms, you can look at the stored-program architecture we use today. Software is data, but it's also data that can direct the hardware to 'do something' in a way that most data cannot. There is software that can introspect itself and modify its own code (this is used both for clever performance hacks and for obfuscation).

My view is that consciousness is a property of my thought processes — not every thought will have the same level of introspection, or even introspection at all. It's something that my mind is doing (or isn't doing, depending on what I'm thinking about). The property we ascribe to entities that we call 'consciousness' I would instead term 'the ability to think consciously' or 'the ability to have consciousness'. It seems to me that my thought processes are software running on the hardware that is the human brain. If my mind were uploaded, and its software state written to permanent storage and then stopped running, I would say that this recorded state still has the ability to think consciously, but it is not doing so, since it's not thinking at all, so at that time it is not conscious. (But of course it could be, if started back up.)

"Leadership skills"?

As you mention in your second footnote, the idea of a 'pickup artist' carries unfortunate connotations. I'd suggest you change your headline to something that you won't have to explain "it's not really what you thought when you first heard it".

Perhaps "Optimizing interaction techniques for social enjoyment"? This has the benefit that while the pickup artist is perceived as interested in social engagement as a means to orgasm, practitioners of the techniques you discuss would be perceived as interested in social engagement as an end in itself.