Philosophers usually seek for and justify moral and political orders by two methodologies. Rationalism claims that social organization of human beings should fit with human nature, and believes that a predefined conception of human nature, defined in terms of human capacities for the exercise of reason, can be established as the independent criterion for choosing and justifying the proper moral and political order. Institutionalism, on the other hand, believes that human nature is at least significantly shaped by the actual construction of moral and political orders by human beings, and by internalizing the social institutions in which they live, they create themselves. In this essay, I argue that rationalism is not a good methodology becau...