In recent decades it has sought to lay the foundations for a social science no longer appealing to its similarity to the natural sciences, but rather looking for qualities of its object of study and the difference representing assumptions about social interactions and those at the level of physics or chemistry (Homans, 1970: 14). _ _ The aim and scope of work. The purpose pursued by this essay is to rescue those contributions made by classic authors in the social sciences, such as Montesquieu, Tocqueville, Comte that paid to the creation of the spirit of scientific rigour in social sciences. It is important to clarify that it is not intended to expose system-wide interpretive social of those authors, but that given the limited nature of this work, What is wanted is capture the way in which these authors faced the difficulties that accounted for their objects of study, methods and categories that were set to give strength to their theories. In the present essay will analyze the ideas of three of the most important social thinkers: Montesquieu, August Comte, Tocqueville. There will be an exposition of his ideas about scientific rationing, as well as a statement of the method used in his most important works. Special care to demonstrate the way in which these authors designed rational models to explain social phenomena will take. While in many cases such models were extrapolated from the natural sciences, with the passage of time is was looking, at least tacitly, new categories of analysis that would be most appropriate for an object of study more dynamic and changing as in the case of the society and the interaction of its members. The purpose of this work is documenting this process and demonstrate how the quest to lay the foundations of rationality in social thought is older than what is believed. There are contributions from classical thinkers that still nowadays continue illuminating and supporting research in the field of social sciences.