First, I would like to demonstrate that it is sometimes permissible to stop a person from killing himself. The example I find most persuasive is that of a person in an acute confusional state (delirium) secondary to a physical illness, such as diabetes. If a person in an acute confusional state walks out into traffic or engages in other self-harming behaviors, I would feel completely justified in intervening and basically forcing the person to stay alive. But why?
In previous posts, I've examined a non-paternalistic explanation of how the right to die might be said to harm some people (though, as I pointed out, this only applies to suicide rights for the terminally ill or catastrophically disabled). It is my view that stopping a person in an acute confusional state from harming himself is also allowed on non-paternalistic grounds, whereas stopping the suicide of a non-delirious person has only paternalistic justifications.
Paternalism obtains when individuals or the state wish to substitute their judgment for that of another, on the grounds that the affected person will make a poor decision. There is a real risk that paternalistic interventions will prevent people from being best off according to their own values. But guiding the deranged diabetic out of traffic is, I argue, not paternalistic, because the action of walking out into traffic, in this limited case, is not based on judgment at all. Put another way, the "person" deciding to walk out into traffic is not really a person at all - the circumstance is not attributable to anyone's will or decision, so intervening with our own will or decision is not paternalistic. George didn't decide to walk out into traffic - his delirium "made" him, and when George gets his insulin shot and comes back to us, "he" will be grateful to us for saving "him" from his illness.
The problem, of course, is how far to apply this idea of a suicide being the result of circumstance, delirium, and illness, rather than the result of a choice by the suicide. Many people seem willing to take the incident of a suicide attempt itself as probative evidence that the person is not in his right mind, that is, acting under something other than his will. The extreme medicalization of depression has allowed society, including the mental health industry, to take the view that suicide is always a sign of illness. (Revealingly, a suicide attempt, in and of itself, is not valid diagnostic criteria even for a major depressive episode under the DSM-IV, though of course, in practice, the elastic criteria for diagnosing depression are often fudged.) These people argue that intervening in an attempted suicide is always permissible - and, perhaps, never paternalistic - because suicide, in this view, is never truly a willed act, and always the result of something outside the person, such as (vaguely defined) illness.
We have to draw a line as to when it's morally permissible to intervene in a suicide attempt, or to withhold the means for suicide from a person. Some, as I have explained, would draw the line at "always." Hopefully my writings of the past two months might give a tiny bit of pause to those folks. At any rate, I don't think the line should be drawn at "always," which leaves me the task of explaining where the line should be drawn.
I am comfortable with preventing suicide in the case that it is attributable to a circumstance that is clearly outside the suicide's will - such as an attack of delirium, or an accident. But in any case where the suicide's will is invoked - where, we might say, the suicide is acting on reasons for ending his life - I am much less open to intervention. This is true even if the suicidal person is culturally defined as having a medical illness, such as depression, and even including many cases where the suicide has a thought disorder or otherwise may be thought to be "incompetent." A person with a mental illness may make a will, for example, as long as he understands the extent of his property, knows who his relatives are, and understands that he is making a will. I am comfortable allowing suicide in situations where a person understands what death is, can articulate his desire for death, and can give non-delusional reasons for his desire. Intervening in a case like this must be seen as at least paternalistic, and must require a much greater justification than intervening in the case of the delirious diabetic. The more an illness is short-term, well understood to be biological in nature, and seems to obliterate the person's will, the more comfortable I am with intervention against suicide. The more an "illness" is long-term, poorly understood, and leaves the person's will apparently intact, the more justification I would require for an intervention.
An interesting point is that many people, under our current system, might attempt suicide as a "cry for help" without actually desiring to die. The data indicates that women in particular are much more likely to make an unsuccessful suicide attempt; many authors infer that women have motivations other than dying when attempting suicide, such as getting more attention or support from those around them. Dena S. Davis responds, in her essay "Why Suicide is Like Contraception," that this is not much of an objection to legalizing suicide, and that the legalization of suicide might encourage people to act authentically:
. . . if assisted suicide became open and legal, perhaps women who otherwise would use a suicide attempt as a "cry for help," will be forced to confront and articulate their real needs. To continue to play a societal game in which women "attempt" suicides they don't really intend, perpetuates a situation in which women are rewarded for communicating one thing and meaning another. This makes it more difficult for women to command respect for their real beliefs and wishes . . . . I make a similar argument with respect to Jehovah's Witnesses and refusal of life-saving treatment in "Does 'No' Mean 'Yes'? The Continuing Problem of Jehovah's Witnesses and Refusal of Blood Products," Second Opinion 19: 35-43 (1994).