Prudence and the Temporal Structure of Practical Reasons

I reject three theories of practical reason according to which a rational agent's ultimate reasons for acting must be unchanging: that one is rationally obliged in each choice (1) to be prudent--to advance all the desires one foresees ever having (the self-interest theory), rather than just those one has at the time of choice, or (2) to cause states of affairs that are good by some timeless, impersonal measure (Thomas Nagel), or (3) to obey permanent, universalizable deontic principles (Kant). Whether a rational agent's reasons consist in her desires, in the goodness of certain states, or in deontic principles, her reasons now can ask her to take different, conflicting things as reasons later; and contradiction results of rationally obliging her not to take the new things for reasons.