Is liberalism adaptable enough to the ecological agenda to deal satisfactorily with the challenges of anthropogenic climate change while leaving its normative foundations intact? Compatibilists answer yes; incompatibilists say no. Comparing such answers, this article argues that it is not discrete liberal principles which impede adapatability, so much as the constructivist model (exemplified in Rawls) of what counts as a valid normative principle. Constructivism has both normative and ontological variants, each with a realist counterpart. I argue that normative constructivism in (...) the Rawlsian mode, whatever its strengths elsewhere, is markedly ill‐equipped to deal with the particular normative challenges posed by climate change – and that that these doubts holds regardless of which stance is adopted as its ontological corollary. (shrink)