This Element denaturalises political science, stressing the contestability and contingency of ideas, traditions, subfields, and even the discipline itself. The history of political science is less one of scholars testing and improving theories by reference to data than of their appropriating and transforming ideas, often obscuring or obliterating former meanings, to serve new purposes in shifting political contexts. Political science arose in the late nineteenth century as part of a wider modernism that replaced earlier developmental narratives with more formal explanations. It changed as some scholars yoked together behavioural topics, quantitative techniques, and positivist theory, and as other scholars rejected their doing so. Subfields such as International Relations remained semi-detached and focused on policy as much as theory. Furthermore, the shifting fashions within political science - modernism, behaviouralism, realism, neoliberalism, the new institutionalism - have informed the policies by which governments have tried to tame contingency and govern people.