Abstract

This dissertation primarily consists of three related, published articles on decision theory. All three articles are at least in part a response to various problems and issues raised by an approach known as "causal decision theory". But "Rationality, Group Choice and Expected Utility" goes beyond the issue of causal versus non-causal decision theory, and deals in general with the subject of analysing rational choice in terms of expected utility. I develop a new way of handling cases of rational cooperation within the framework of a straight-forward expected utility analysis. This new approach is employed to resolve The Prisoners' Dilemma and other paradoxical cases of group choice. Both "Counterfactuals and Newcomb's Paradox" and "Rationality Revisited" challenge the claim that causal decision theory adequately captures our notion of rational choice. In particular, both articles take issue with the causal theorist's approach to the infamous Newcomb's Paradox, since that is generally regarded as a pivotal case. It is important to note that the two articles individually provide quite independent arguments for the claim that non-causal decision theorists should not be persuaded by the causal theorist's account of Newcomb's Paradox. Both "Rationality, Group Choice and Expected Utility" and "Rationality Revisited" develop the surprising finding that there is a clear sense in which it is not necessarily true that rationality requires an agent to choose the option that he can determine to have the highest payoff. It is the failure to realize this that leads one astray in Newcomb's Paradox.