Mechanical solidarity is characterised in traditional societies with simple division of labour. Individuals are highly constrained by the values, norms and regulation of the society. When member deviates from this norms he might be most probably rejected by the group. Individualism is not supported ad degrees of freedom are few. Organic solidarity is common for contemporary societies where there is higher differentiation of labour. Differentiation of labour is happening in relation to population density.
More and more people are living in same area with similar activities. Tension is rising, and the only way to overcome these tensions is to have more specialised activities. Division of labour develops in relation to population density. Individuals are having their own specialities and are mutually dependent. Differentiated societies are creating unique individual. Individual has personal opinion, religion, freedom.... and there is clear line between them and society (private problems and public concerns).
The division of labour is not making only marked exchange relationship but the feeling of solidarity. Social solidarity consists of integration of individuals and regulation. Social solidarity is social fact that can be observed only by external indicators, like the law. Law tends to be repressive and restitutive. Conformity in mechanic society is held by repressive system, while conformity in organic societies is held by restituitive force. Two abnormal situations in organic societies is anomie and egoism.
Suicide He explained suicide in terms of the degree to which a person is joined into social life. At the low end of social unity, there is anomic suicide, in which people destroy themselves because social bonds die and life becomes meaningless to them. Then when people are tightly integrated and there is a threat to the social group, people may sacrifice themselves in order to protect the group. Anomic suicide also proved that suicide increases as society falls apart.