Political realists complain that much contemporary political philosophy is insufficiently attentive to various facts about politics yet some political philosophers insist that any critique of normative claims on grounds of unrealism is misplaced. In this paper I focus on the methodological position G.A. Cohen champions in order assess the extent to which this retort succeeds in nullifying the realist critique of contemporary political philosophy. I argue that Cohen’s work does not succeed in doing so because the political principles that we (...) are prepared to endorse are hostage to various fact-sensitive judgements about how they apply to the political domain. I then argue that this discredits various philosophical approaches to political theorising which begin by utilising non-political thought-experiments, such as Cohen’s own Why Not Socialism? (shrink)