His findings can be summarized in one word: constraints. No matter how he parsed the data, people who had fewer social constraints, bonds, and obligations were more likely to kill themselves. Durkheim looked at the “degree of integration of religious society” and found that Protestants, who lived the least demanding religious lives at the time, had higher suicide rates than did Catholics; Jews, with the densest network of social and religious obligations, had the lowest. He examined the “degree of integration of domestic society”—the family—and found the same thing: People living alone were most likely to kill themselves; married people, less; married people with children, still less. Durkheim concluded that people need obligations and constraints to provide structure and meaning to their lives: “The more weakened the groups to which [a man] belongs, the less he depends on them, the more he consequently depends only on himself and recognizes no other rules of conduct than what are founded on his private interests.”
Jonathan Haidt – The Happiness Hypothesis: Finding Modern Truth in Ancient Wisdom p.133
The Sea Is Not Full 