Imagine a life graphed according to utility over time. In the stock market analogy, utility is a function of the price at a particular point (y value at a particular x) whereas in the life graph, utility is the area under the curve.
If the life has negative expected utility beyond a given point, total utility is greater if it's cut off at that point. The ability to cut it off at a later point doesn't change the calculation, because what matters is area under the curve; it doesn't matter if the variance is high and the temporary utility sometimes hits positive values if the average is still negative.
If you're being genuinely rational, and you expect that your future has a negative average utility, then you must either expect that you will also expect in the future that your future has negative average utility, or you must expect that the near future negative utility is greater than the far future positive utility, or you must expect that the far future negative utility outweighs the near future positive utility.
In the last case, it would be rational to continue living until you reach the point of negative expected utility, but you almost certainly aren't contemplating suicide yet in any case. In the first two, expected utility is lower if you postpone suicide than if you do not.
The key problem with suicidal individuals attempting to follow this model is that people contemplating suicide are almost invariably biased with regards to their predictions of future utility.
The ability to cut it off at a later point doesn't change the calculation
Consider two people identical in every respect except that starting tomorrow the first person will always be watched and will never be capable of committing suicide whereas the second will always be capable of committing suicide. Do you contend that their rational calculation for whether they should commit suicide today is the same?
Or, are you saying that a person should kill himself if and only if doing so would increase his expected utility? I don't think, however, this was implied by khafra's post
I was saddened to learn of the recent death by suicide of Chris Capel, known here as pdf23ds. I didn't know him personally, but I was an occasional reader of his blog. In retrospect, I regret not having ever gotten into contact with him. Obviously, I don't know that I could have prevented his death, but, as one with mental-health issues myself, at least I could have made a friend, and been one to him. Now I feel a sense of disappointment that I'll never get that chance.
Having said that, I must say that I take his arguments here very seriously. I do not consider it to be automatic that every suicide is the "wrong" decision. We can all imagine circumstances under which we would prefer to die than live; and given this, we should also be able to imagine that these kinds of circumstances may vary for different people. And if one is already accepting of euthanasia for incurable physical suffering, it should not be that much of a leap to accept it for incurable psychological suffering as well.
Of course, as Chris acknowledges, this doesn't imply that everyone who is contemplating suicide is actually being rational. People may for instance be severely mistaken about their prospects for improvement, especially while in the midst of acute crisis.(Conceivably, that could even have been his own situation.) Nonetheless, I think many of the usual arguments that people use to show that suicide is "wrong" are bad arguments. For example, consider what is probably the most common argument: that committing suicide will inflict pain upon friends and family. It frankly strikes me as absurd (and grotesquely unempathetic) to suppose that someone for whom life is so painful that they would rather die somehow has an obligation to continue enduring it just in order to spare other people the emotion of grief (which they are inevitably going to have to confront at some point anyway, at least until we conquer all death).
Ironically, society's demonization of suicide and suicidal people has negative consequences even from the standpoint of preventing suicide itself, as Chris points out:
It seems to me very possible that our society's fervor to prevent suicide may result in denying severely depressed people the compassion they need. This could theoretically be worth it if it prevented enough suicides that turned out to be worth preventing, but cases like Chris's raise doubt about this, in my mind. (From both angles: if Chris's decision was the right one for him, then the system is saving people it shouldn't be saving; if on the other hand it was the wrong decision, then we clearly see how the system failed him.)
Although I'm inclined to be sympathetic to Chris's view -- perhaps because I haven't always been maximally enthusiastic about my own existence myself -- there are some arguments that do worry me. Such as: if you think of future versions of yourself as separate agents, then suicide is a form of homicide. However, usually suicide is carried out on the belief that the future selves would approve of their nonexistence; and all of our decisions have consequences (often irreversible) for our future selves, so this is a general ethical problem that transcends the specific issue of suicide.
This post is a place to rationally discuss the ethics and rationality of suicide, as well as our attitudes (on an individual level, and as reflected in our institutions) toward suicidal people and, more generally, those suffering from psychological conditions such as depression.
I'm sad that Chris won't be able to participate.