Behavioural Evidence, Yes; Normative Behaviourism, No

Floyd defends normative behaviourism against ‘mentalism’. His characterization of political philosophy as mentalism is uncharitable, and it is not clear that normative behaviourism provides greater evidence of convergence that we find in liberal political philosophy. To interpret behaviour, one must theorize the effects of institutions on that behaviour, it is therefore problematic to defend institutions on behavioural grounds alone without ‘mentalistic’ theory. Normative behaviourism uses a ‘contingent imperative’; however, this leaves the behaviour normatively undefended. A potential response by Floyd to these criticisms depends upon misinterpreting Cohen’s argument that fact-free principles underlie all policy recommendations. Floyd’s own recommendations require at least one fact-free principle in Cohen’s sense. Floyd is correct that behavioural evidence is important to political philosophy.