2 Grape decisions : decision theory and novel experience

New things happen to people all the time, and there is nothing surprising in that. But people also constantly make decisions about new things, and there is something strange about that. From tasting a novel dish to moving to an unknown city, from going on a date to going to war, how can people reasonably choose the unknown? A rational decision maker makes her choice by considering the costs and benefits of an outcome and weighing it against alternatives, and she can use simple probabilities to capture simple uncertainties. But what should she make of cases where she does not know the costs and benefits? And what should she do when the decision will alter her very core, the beliefs and desires she considers when making a decision? Philosophical investigations of how people change their self in light of new experiences are not themselves new (Locke, 1700). Some of the oldest philosophy centers on this theme, such as Heraclitus’ dictum: ‘No person ever steps in the same river twice, for it’s not the same river and they’re not the same man’ (Robinson, 1987). More recent philosophical work has explored both the di culty of rationally reasoning about the self (Jackson, 1986; Parfit, 1984), and the fundamental di culty of applying standard decision-making frameworks to big, self-altering decisions (L. A. Paul, 2014; Ullmann-Margalit, 2006). In this chapter, we consider the psychological architecture that supports decisions about novel and transformative experiences, in light of advances in the computational modeling of thought. The first half shows how people can make informed decisions about trying unfamiliar things, by using rational inductive inference to evaluate novel experiences. This inference integrates previous experience, current preferences, and an understanding of how the world is organized, using a non-parametric hierarchical Bayesian model (Gri ths, Kemp, & Tenenbaum, 2008; Tenenbaum, Kemp, Gri ths, & Goodman, 2011) to capture the structural uncertainty in such decisions. The model also accounts for higher-level decisions, by allowing for higher-order preference: people can decide to try something new because they like the novelty of it, regardless of the particular immediate sensation that experience brings. The second half of the chapter tackles decisions about transformative experiences, meaning choices that can a↵ect people’s self, including people’s decision-making faculty and the preferences it relies on. Reasoning about such choices requires that people have a theory-of-self, similar to the theory-of-mind they have of others. We present a formal framework for adjudicating between selves based on such a theory-of-self, and explore several alternative models within this general framework. We use both formal modeling techniques and empirical work to compare the di↵erent models within these framework, and end by considering what is still left out of a descriptive, computational account of making big decisions. While we regard the following work as an important contribution to the philosophical and psychological issues around transformative experience, we consider the empirical results as initial explorations, and setting up the edifice for future work into attitudes towards real-world transformative experience.