Abstract

We typically have to act under uncertainty. We can be uncertain about the relevant descriptive facts, but also about the relevant normative facts. However, the search for a theory of decision-making under normative uncertainty is doomed to failure. First, the most natural proposal for what to do given normative uncertainty faces two devastating problems. Second, the motivations for wanting a theory of what to do given descriptive uncertainty do not carry over to normative uncertainty. Descriptive facts may be inaccessible even in principle, and ignorance of them excuses one from blame, but normative facts are in principle accessible, and ignorance of them arguably is no excuse. Normative facts differ from descriptive facts: normative facts affect what we ought to do no matter what, while descriptive facts affect what we ought to do only insofar as we are aware of them.