Medical geography begins with sickness and health. The policies addressing disease, and the causes promoting good health are, literally, vital. Here, as in social science as a whole, an historical perspective helps: Things could have been different and may yet be different again. Parallels between past and present propose lessons for today. This approach is well captured in Mitchell Dean’s summary of Michel Foucault’s project as the writing of critical and effective history. Critical history highlights the contingency of the present, and effective history gives us resources with which to consider alternatives. An important and contested area that is illuminated by such a “political historicism” is the nature of the social. This has both a material and a discursive context and both are essential for medical geographers. Its material setting includes the biological conditions of human existence. These conditions are resolutely social. Historians influenced by Foucault have described the emergence of the social as a distinct field of knowledge, expertise and government. There is now a corpus of important geographical works on the emergence of social policy in the areas of health, sickness, welfare, and urban planning. Public health is one area where this discovery and invention of the social occurs repeatedly. Far from being the individualistic Robinson Crusoe of liberal or bourgeois ideology, human beings require a social shell if they are to thrive.