Durkheim turned Comte's program into a working science by establishing what its object was and how it could be studied without collapsing into psychology.
His founding rule is that social facts must be treated as things: they exist outside any particular individual, they exercise constraint on him, and they are to be explained by other social facts rather than by the intentions of the people who bear them. Language, law, currency and religion are not the sum of individual choices; they precede each individual and shape what he can choose.
The Division of Labour in Society (1893) argued that solidarity itself changes form as societies grow more differentiated — from a mechanical likeness in which people are bound by shared belief, to an organic interdependence in which they are bound by needing one another. Suicide (1897) is the demonstration piece: the most private imaginable act shows stable rates that vary by confession, marital status and political circumstance, and therefore belongs to the group rather than the person. It also gave the discipline anomie — the condition in which the norms regulating desire have broken down, which he thought the characteristic pathology of rapid modernisation.
The politics is liberal but not individualist. Durkheim held that the state exists to free the individual from the local groups that would otherwise dominate him, but that a society of individuals facing an unmediated state is unstable; his proposed remedy was occupational corporations standing between the two. That argument runs directly into twentieth-century pluralism and the corporatist strands of both social democracy and Catholic social teaching.