One can find many proposals for policy responses to global environmental problems. Different disciplines - notably economics, geography, innovation studies, policy and political sciences, psychology and sociology - offer partly inconsistent advice. This undermines the social-political acceptance of policies as voters and politicians are likely to be left confused. To decide about an adequate sustainability policy mix we need to concur on the core problems such a mix has to tackle. I address four of these hereafter. Each one involves important issues of disagreement as well as unresolved questions.