Suppose we have a persistent disagreement about a particular set of policy options, not because of an underlying moral disagreement, or a mere conflict of interest, but rather because we disagree about a crucial non-normative factual assumption underlying the justification of the policy choices. The main question in the paper is what political legitimacy requires in such cases, or indeed whether there are defensible answers to that question.
The problem of political legitimacy in fact-dependent policy disagreements has received almost no attention in political philosophy, which has focused mostly on value disagreements and proposed theories of legitimate coercive legislation in value-dependent disagreements. The paper presents an argument showing that under certain plausible assumptions regarding legitimacy, there are serious difficulties in identifying legitimate choices in fact-dependent policy disagreements. This may be unsurprising to political philosophers preoccupied with value-based disagreements, perhaps because it has been assumed that legitimacy-related concerns are irrelevant (or do not apply) to fact-dependent policy disagreements. The paper argues that this response is premature. If we should care about legitimacy at all, then it is by no means clear why we should ignore issues of legitimacy in policy-disputes that depend on factual disagreements. The paper ends by defining a set of possibilities that merit further exploration in search of a theory of legitimacy in fact-dependent policy disagreements.