Abstract

The task of this dissertation is to solve a puzzle about morality and prudential rationality. The puzzle is that we want to always act both morally and rationally but sometimes we cannot. Many philosophers try to solve the puzzle by showing that morality and prudential rationality are always consistent or showing that one is always superior to the other, but, as I shall argue, this is impossible. I explore different theories of practical rationality under four major categories: agent-relative internalism and externalism, and agent-neutral internalism and externalism. I believe that moral reasons are identical to certain sorts of agent-neutral reasons. Therefore, it should always be rational to act morally, though in a sense of rationality different from that of prudential rationality. Thus, the puzzle becomes the puzzle about certain agent-neutral reasons and agent-relative reasons. In this dissertation, I try to show that the incommensurability between the grounds of moral reasons and agent-relative reasons makes comparison between the powers of the two kinds of reasons impossible. Therefore we cannot prove that morality and prudential rationality are always consistent or that one is always superior to the other. To remove the puzzle, we have to give up the desire to always act both morally and prudentially. If we still want to determine what the agent has most reason to do when the two sorts of reasons conflict in a particular situation, what we can do, at most, is to appeal to our normal sense or intuition, which can be defined as an ability or power to recognize some self-evident truths or statements. If there is no universal normal sense or intuition, what we can do is to vote or appeal to reflective public opinion, which is justified by intuitions of the majority of the rational people in a community who really understand the relevant situation. If voting and reflective public opinion still cannot determine what the agent has most reason to do, in that case we can only determine what the agent has reason, but not most reason, to do