Abstract

I investigate the logical connections between two common kinds of object of desire used in decision theory and microeconomics, and arguments about the rationality of choosing time-preferentially. One kind of object of desire is atemporal and is common in philosophical discussions of time preference. An atemporal object is an action or physical object, such as a massage or a new car. The time of availability or consumption is not an individuating characteristic of atemporal objects. The other kind of object is dated, and is common in economists' discussions of time preference. A dated object is an action-at-a-time, or a physical-object-at-a-time, such as today's massage or next year's new car. The time of availability or consumption is an individuating characteristic of dated objects. Arguments about the rationality of time preference from philosophers Thomas Nagel, John Rawls and Henry Sidgwick are examined, along with arguments from economists F. A. Hayek, Ludwig von Mises and Murray Rothbard. It is observed that the philosophers assume that our objects of desire are atemporal while the economists assume that our objects of desire are dated. The effects which these assumptions have on the writers' arguments about the rationality of time preference are explored. It is found that under a set of ceteris paribus conditions, arguments assuming atemporal objects tend systematically to assert that time preference is irrational, while arguments assuming dated objects tend systematically to assert that time preference is rational--often through circularity. The logical connections are investigated between the two different objects of desire on one hand, and the premises of the arguments, the respective definitions of time preference, and standards of rationality on the other hand.