Richard Pettigrew

Leon Horsten

A single volume reference guide to the latest work and potential future directions in Philosophical Logic, written by an international team of leading scholars.

The Continuum Companion to Philosophical Logic

What we value, like, endorse, want, and prefer changes over the course of our lives, sometimes as a result of decisions we make—such as when we choose to become a parent or move to a new country—and sometimes as a result of forces beyond our control—such as when our political views change as we grow older. This poses a problem for any theory of how we ought to make decisions. Which values and preferences should we appeal to when we are making our decisions? Our current values? Our past ones? Our future ones? Or some amalgamation of all them? But if that, which amalgamation? In Choosing for Changing Selves, Richard Pettigrew presents a theory of rational decision making for agents who recognise that their values will change over time and whose decisions will affect those future times.

Choosing for Changing Selves

Our beliefs come in degrees. I'm 70% confident it will rain tomorrow, and 0.001% sure my lottery ticket will win. What's more, we think these degrees of belief should abide by certain principles if they are to be rational. For instance, you shouldn't believe that a person's taller than 6ft more strongly than you believe that they're taller than 5ft, since the former entails the latter. In Dutch Book arguments, we try to establish the principles of rationality for degrees of belief by appealing to their role in guiding decisions. In particular, we show that degrees of belief that don't satisfy the principles will always guide action in some way that is bad or undesirable. In this Element, we present Dutch Book arguments for the principles of Probabilism, Conditionalization, and the Reflection Principle, among others, and we formulate and consider the most serious objections to them.

Dutch Book Arguments

Richard Pettigrew offers an extended investigation into a particular way of justifying the rational principles that govern our credences (or degrees of belief). The main principles that he justifies are the central tenets of Bayesian epistemology, though many other related principles are discussed along the way. These are: Probabilism, the claims that credences should obey the laws of probability; the Principal Principle, which says how credences in hypotheses about the objective chances should relate to credences in other propositions; the Principle of Indifference, which says that, in the absence of evidence, we should distribute our credences equally over all possibilities we entertain; and Conditionalization, the Bayesian account of how we should plan to respond when we receive new evidence. Ultimately, then, this book is a study in the foundations of Bayesianism. To justify these principles, Pettigrew looks to decision theory. He treats an agent's credences as if they were a choice she makes between different options, gives an account of the purely epistemic utility enjoyed by different sets of credences, and then appeals to the principles of decision theory to show that, when epistemic utility is measured in this way, the credences that violate the principles listed above are ruled out as irrational. The account of epistemic utility set out here is the veritist's: the sole fundamental source of epistemic utility for credences is their accuracy. Thus, Pettigrew conducts an investigation in the version of Iepistemic utility theory known as accuracy-first epistemology. The book can also be read as an extended reply on behalf of the veritist to the evidentialist's objection that veritism cannot account for certain evidential principles of credal rationality, such as the Principal Principle, the Principle of Indifference, and Conditionalization.

Richard Pettigrew

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