Eudaemonism is the common structure of the family of theories in which the central moral conception is eudaemonia , understood as "living well" or "having a good life." In its best form, the virtues are understood as constitutive and therefore essential means to achieving or having such a life. What I seek to do is to lay the groundwork for an approach to eudaemonism grounded in practical reason, and especially in instrumental reasoning, rather than in natural teleology. In the first (...) chapter, I argue that an approach based in natural teleology will not work. In the second, the claims of decision theory to be an adequate formal representation of instrumental reasoning are examined and found wanting. In the third, I develop an account of ordinary instrumental reasoning. In the fourth, I discuss the structure of eudaemonism, with the aim of showing that there is an intelligible and attractive doctrine that can be disentangled from the natural teleology. In the fifth, I sketch an argument showing that instrumental reasoning, as explicated in the third chapter, can bear on the selection of final and ultimate ends, and that it is plausible that the instrumental approach to moral theory that I am urging yields conclusions with a eudaemonistic structure. I also indicate directions for further development and exploration. (shrink)