The one main point of Emile Durkheim's seminal "Suicide" (1987) is that suicide, or any other personal act for that matter, is never a purely individual act bur rather one that incorporates social conditions. Thus suicide for Durkheim is the result of a certain type of relationship between an individual and society. "Suicide" is Durkheim's attempt to create a model case study that deals with what he calls "social fact" (see our summaries of Durkheim's What is Social Fact? or "The Rules of Sociological Method" for more details). These social facts work to determine an individual's life, and in some cases, his death by his own hands.
In "Suicide" Durkheim compares suicide rates of Protestants and Catholics, holding that Catholics kill themselves less. His explanation was that Catholicism offers its followers a stronger sense of social cohesion and a feeling of belongingness when compares with the more individualistic Protestants.
When studying the family Durkheim noted that men commit more suicide than women and that singles kill themselves more than people in relationships, people with children present even smaller rates of suicide. Durkheim also found that soldiers kill themselves more than civilians and that they do so more in peacetime than during war.
These findings lead Durkheim to argue that suicide is prompted by social factors, and not only psychological ones. The relationship one has with his social world is determinative of his inner experience, and should these ties become problematic people might be driven to suicide. Durkheim feels that social integration and cohesion are important here, holding that the more you are comfortably bound with your social surrounding the less you are likely to kill yourself. One the other hand, being too close to society to the point of losing the self can also lead one to commit suicide.
Durkheim lists four types of suicide (see link for a detailed summary):
Anomic suicide (see Anomie) is the result of the destabilization and ultimate breakdown of ties to social reality, like in times of rapid change.
Egoistic suicide happens due to the loss of social ties and isolation from society, like in the case of old age.
Altruistic suicide is when someone willingly gives his life to society with which he indentifies completely. Soldiers dying for their country is an example.
Fatalist suicide for Durkheim is when someone is erased by society, losing all sense of self and agency. A prisoner killing himself is an example.
See also: Suicide as a Social Phenomenon