If there is a single innovation that characterizes nineteenth-century social thought as a whole, it is the apparently simple idea that “society” is not the same thing as “the state.” That is, the practices and institutions that make up society are distinct in nature and function from those that define the political sphere. Although nineteenth-century thinkers disagree over both what society is and how it differs from the state, there is among them widespread (though not universal) consensus that a major shortcoming of their predecessors – Montesquieu and Rousseau are two of the more illustrious examples – was their failure to distinguish clearly between social and political forms of association. Once this distinction is made, however, a further issue arises: If society and the state are different subject matters, might they not also demand different methods of study? And if so, what is the study of society to look like? Impressed, no doubt, by the scientific advances of the previous two centuries, social philosophers of the nineteenth century generally agreed, in response to these questions, that their task was to found a science of society, and so thinking about what such a science would consist in became a second major preoccupation of social thought in this period. A third, somewhat independent concern of much of nineteenth-century social thought was the extent to which society is to be conceived on the model of a living organism. Even though all the thinkers to be examined here accepted some version of this analogy, they disagreed widely over precisely how societies were like organisms and, even more, over what those similarities implied.