Emile Durkheim (1858-1917) largely contributed to the field of sociology, to the point of being deemed as one of the most important forefathers in the field.
The reason is that Durkheim is one of the few sociologists who viewed this field as something unique that had elements of psychology as well as elements of science but that it does not necessarily means that is one or the other.
In Durkeim's dissertation The Division of Labor in Society Durkheim focuses on the term "solidarity" as one of the most important social elements. Individuals find solidarity either mechanically, or impulsively. This solidarity is ultimately what divides society into clusters. For this reason, it is not correct to suppose that solidarity could be explained merely under psychological or scientific methods. Sociology, argues Durkheim, must be studied separately.
Having given sociology its own place, Durkheim basically made sociology a formal field of study that includes the application of the scientific process as well as the inclusion of psychological concepts. This combination helps to understand how individuals become a collective group, and to which extent solidarity affects all individuals.