Theoria, Issue 160, Vol. 66, No. 3 (September 2019): 27-52 © Berghahn Books doi:10.3167/th.2019.6616003฀•฀ISSN฀0040-5817฀(Print)฀•฀ISSN฀1558-5816฀(Online) Internal Reasons and the Problem of Climate Change David Hall Abstract: Climate action is conventionally framed in terms of overcom- ing epistemic and practical disagreement. An alternative view is to treat people’s understandings of climate change as fundamentally pluralistic and to conceive of climate action accordingly. This paper explores this latter perspective through a framework of philosophical psychology, in particular Bernard Williams’s distinction between internal and external reasons. This illuminates why the IPCC’s framework of ‘Reasons for Concern’ has an inefficacious relationship to people’s concerns and, hence, why additional reason giving is required. Accordingly, this paper recommends a model of truthful persuasion, which acknowledges the plurality of people’s motivations and sincerely strives to connect the facts of climate change to people’s subjective motivational sets. Keywords: Bernard Williams, climate change, climate communication, political philosophy, political psychology, political theory As far as public problems go, the problem of climate change is profound. The practical challenge can be stated generically; for instance, to act appropriately in light of knowledge of climate change. But acting appropriately has proven extraordinarily diffi- cult. Although the human species has possessed scientific evidence of carbon dioxide’s potential for radiative forcing since at least the late nineteenth century, global greenhouse gas emissions have con- tinued to rise. 1 The backdrop to this climate inaction is disagreement. People disagree over whether climate change is actually occurring or is