Reflection, Introspection, and Book

The much-debated Reflection principle states that a coherent agent’s credences must match their estimates for their future credences. Defenders claim that there are Dutch-book arguments in its favor, putting it on the same normative footing as probabilistic coherence. Critics claim that those arguments rely on the implicit, implausible assumption that the agent is introspective: that they are certain what their own credences are. In this paper, we clarify this debate by surveying several different conceptions of the book scenario. We show that the crucial disagreement hinges on whether agents who are not introspective are known to reliably act on their credences: if they are, then coherent Reflection failures are (at best) ephemeral; if they aren’t, then Reflection failures can be robust— and perhaps rational and coherent. We argue that the crucial question for future debates is which notion of coherence makes sense for such unreliable agents and sketch a few avenues to explore.