Garrett Cullity

This critical study of John Broome’s Rationality Through Reasoning raises some questions about the various requirements of rationality Broome formulates, pointing out some apparent gaps and counterexamples; proposes a general description of rationality that is broadly consistent with Broome’s requirements while providing them with a unifying justification, filling the gaps, and removing the counterexamples; and presents two objections to the book’s broader argument concerning the nature and importance of reasoning.

What is the significance of empirical work on moral judgement for moral philosophy? Although the more radical conclusions that some writers have attempted to draw from this work are overstated, few areas of moral philosophy can remain unaffected by it. The most important question it raises is in moral epistemology. Given the explanation of our moral experience, how far can we trust it? Responding to this, the view defended here emphasizes the interrelatedness of moral psychology and moral epistemology. On this view, the empirical study of moral judgement does have important implications for moral philosophy. But moral philosophy also has important implications for the empirical study of moral judgement.

Morality, it is commonly argued, cannot be extreme in the demands it makes of us, because “ought” implies “can”, and normal human psychology places limits on the extent to which most of us are capable of devoting our lives to the service of others. To evaluate this argument, we need to distinguish different uses of “ought” and “can”. Having distinguished these uses, we find that there is more than one defensible version of the principle that “ought” implies “can”. However, these distinctions can also be deployed to show that the attempt to argue from this principle to the conclusion that morality cannot be extremely demanding fails.