Durkheim considered society as sui-generis and a reality in itself and whole is greater than its parts- individual. Similarly social facts could not be reduced to individual facts.Social facts are defined as ways of acting thinking and feeling which are exterior to an individual and hence endowed with a power of coercion over them. The four main characteristics of social facts are their generality, externality and constraints or coercive power. They have distinctive social characteristic which are not amenable to explanation on either biological or psychological level e.g. social facts are suicide, fashion etc.
Since it is not dependent on one individual but is concerning everybody in society. It is a general phenomenon is an external observable phenomenon and has certain control over individual. Hence Durkheim considered that social facts should be treated as things. They should be observed objectively and not treated as concepts. Social facts are seen as effective guides and controls of conduct only to the extent that they become internalised in the consciousness of individuals while continuing to exist independently of individual.