Corky - too long to quote the whole thing in full
http://plato.stanford.edu/entries/suicide/#MorRatSui3.6 Autonomy, Rationality, and Responsibility
A more restricted version of the claim that we have a right to noninterference regarding suicide holds that suicide is permitted so long as—leaving aside questions of duties to others—it is rationally chosen, or to put it in a Kantian vernacular, if it is undertaken autonomously. This position is narrower than the libertarian view, in that it permits suicide only when performed on a rational basis and permits others to interfere when it is not performed on that basis.
This approach has given rise to a rich philosophical literature concerning the conditions for rational suicide. For the most part, this literature divides the conditions for rational suicide into cognitive conditions, conditions ensuring that individuals' appraisals of their situation are rational and well-informed, and interest conditions, conditions ensuring that suicide in fact accords with individuals' considered interests. Richard Brandt captures the spirit of this approach:
The person who is contemplating suicide is obviously making a choice between future world-courses: the world-course that includes his demise, say, an hour from now, and several possible ones that contain his demise at a later point… The basic question a person must answer in order to determine which world-course is best or rational for him to choose, is which he would choose under conditions of optimal use of information, when all of his desires are taken into account. It is not just a question of what we prefer now, with some clarification of all the possibilities being considered. Our preferences change, and the preferences of tomorrow are just as legitimately taken into account in deciding what to do now as the preferences of today (Brandt 1975).
Other examples of this approach include Glenn Graber, who states that a suicide is rationally justified “if a reasonable appraisal of the situation reveals that one is better off dead.” (Graber 1981, 65). An appraisal is reasonable, according to Graber, if one judges rationally about the likelihood of her present and probable future values and preferences being satisfied. On Graber's view, a suicide is rational if it results from a clearheaded assessment of how suicide would further or impede one's overall interests. Margaret Battin identifies three cognitive conditions for rational suicide (a facility for causal and inferential reasoning, possession of a realistic world view, and adequacy of information relevant to one's decision), along with two interest conditions (that dying enables one to avoid future harms, and that dying accords with one's most fundamental interests and commitments) (Pabst Battin 1996, 115).
For the most part, suicidal individuals do not manifest signs of systemic irrationality, much the less the signs of legally definable insanity, (Radden 1982) and with the exception of severe psychopaths, engage in suicidal conduct voluntarily. However, these facts are consistent with the choice to engage in suicidal behavior being irrational, and serious questions can be raised about just how often the conditions for rational suicide are met in actual cases of self-inflicted death. Indeed, the possibility of rational suicide requires that certain assumptions about suicidal individuals' rational autonomy be true which may not be in many cases. A person's choice to undertake suicidal behavior may not be a reflection of her true self and her self-inflicted death could be an act that she would, in calmer and clearer moments, recoil at. In other words, even if there is a right to self-determination which in turn implies a right to suicide, it seems to imply a right to commit suicide only when one's true self is making that determination, and there are numerous factors that may compromise a person's rational autonomy and hence make the decision to engage in suicidal behavior not a reflection of one's considered values or aims. Some of these factors cognitively distort agents' deliberation about whether to commit suicide. The act of suicide is often impulsive and poorly thought out, reflecting the intense psychological vulnerability of suicidal persons and their proclivity toward volatility and agitation (Cholbi 2002). Suicidal persons can also have difficulty fully acknowledging the finality of their death, believing that (assuming there is no afterlife) they will continue to be subjects of conscious experience after they die. In what are known as dyadic suicides, the suicidal individual actually looks forward to the moment when she will (posthumously) enjoy having insulted or having exacted revenge upon another person.
Particularly worrisome is the evident link between suicidal thoughts and mental illnesses such as depression. While disagreement continues about the strength of this link (Pabst Battin 1996, 5) little doubt exists that the presence of depression or other mood disorders greatly increases the likelihood of suicidal behavior. Some studies of suicide indicate that over 90% of suicidal persons displayed symptoms of depression before death, while others estimate that suicide is at least 20 times more common among those with clinical depression than in the general population. In cases of suicide linked with depression, individuals' attitudes toward their own death are colored by strongly negative and occasionally distorted beliefs about their life situations (career prospects, relationships, etc.). As Brandt (Brandt 1975) observed, depression can “primitivize one's intellectual processes,” leading to poor estimation of probabilities and an irrational focus on present suffering rather than on possible good future states of affairs. The suicidally depressed also exhibit romanticized and grandiose beliefs about the likely effects of their deaths (delusions of martyrdom, revenge, etc.) Furthermore, suicidal persons are often hesitant about their own actions, hoping that others will intervene and signaling to others the hope that they will intervene (Shneidman 1985). Finally, although repeated suicide attempts by the same individual are common, the impulse to suicidal behavior is often transient and dissipates of its own accord (Blauner 2003). Taken together, these considerations indicate that, even if there is a right of self-determination, the scope of suicidal conduct that genuinely manifests fully informed and rational self-evaluation may be rare and so only occasionally will suicide be rational or morally permissible, even when excusable because irrational. (Philip Devine has even argued that suicide is necessarily irrational: Because no one has experience of death, a suicidal individual lacks the knowledge needed to judge continued life with its alternative (Devine 1978). See also Cowley 2006.) Moreover, if suicide is frequently not an expression of individuals' rational self-determination about their well-being, that suggests that others may have a prima facie reason to interfere with suicidal behavior and so is there is no general right to noninterference. (See section 3.7)
