Abstract

Decision theory cannot be a purely formal theory, free of all metaphysical assumptions and ascertainments. It must instead rely upon the end user for the wisdom it takes to prime the decision formalism – with principles and assumptions about the metaphysics of the application context – so that the formalism in its turn can generate good advice. Appreciating this idea is fundamental to understanding the true rivalry between evidential decision theory (EDT) and causal decision theory (CDT) in specific cases. I shall argue that no decision theory can deliver a verdict unless assumptions are made about the degrees of freedom in the context of decision, that EDT and CDT disagree fundamentally about how to diagnose the degrees of freedom in any given situation, and that from this fundamental disagreement flow their surface disagreements in iconic cases.