Docenti: prof. Joe Roussos, Institute for Futures Studies, Stockholm

Periodo: I semestre a.a. 2025/26

Numero di ore: 12

Tipo di didattica: lezioni frontali e dibattito con gli alunni

Programma:
Philosophical decision theory is about how we ought to make rational decisions. This intensive course will introduce the core concepts of philosophical decision theory. We will start by examining what a “decision theory” is, and how decision theory fits into philosophy, economics and psychology. Then, we will discuss the logic of preferences and the logic of belief. These are two central inputs to a theory of decision. With this in place, we will look at three decision theories for situations of increasing uncertainty. Finally, we will introduce some contemporary issues in decision theory: risk aversion and ambiguity. The course requires some background in logic and analytic philosophy, but is otherwise self-contained. It will consist of lectures, discussion, and exercises.

1. What is decision theory
      - Introduce the concept of a decision theory. Situate decision theory in philosophy, economics, and psychology. Discuss the project of formally modelling decisions. Introduce core concepts: decision, decision table, desires and beliefs.
2. Logic of preferences
      - The link between preference and choice. What are the rational constraints on preferences? Transitivity, cycles of preference, and money pumps. Completeness of preference. Independence of irrelevant alternatives vs. context. 
3. Logic of beliefs
      - Introducing subjective confidence as an attitude. Rational constraints on confidence: transitivity, monotonicity over entailment. How much logical insight is reasonable to assume? Completeness of confidence.
4. Representations
      1. Certain preference -> utility. Choice in which there is no uncertainty and one simply chooses between alternatives. The representation of utility. Uniqueness up to positive affine transformations. Different scales of measurement: ordinal, ratio, cardinal. (Formal detail provided)
      2. Risky preference -> expected utility. Choice in which there are known probabilities, e.g., casino gambling. von Neumann-Morgenstern expected utility theory. Uniqueness conditions. (Moderate level of formal detail)
      3. Uncertain preference -> subjective expected utility. Choice in which there is uncertainty and no given probabilities. Subjective probability. Subjective expected utility theory. Uniqueness conditions. (Little formal detail)
5. Beyond Expected Utility
      1. Allais choices -> risk aversion. The Allais choice. Is risk aversion rational? The empirical data on risk attitudes. Difference ways to represent risk aversion in economics and philosophy. Maybe: Buchak’s theory of risk-weighted expected utility.
      2. Ellsberg choices -> non-probabilistic beliefs. The Ellsberg choice. Is ambiguity aversion rational? Moving away from probabilistic beliefs. The relationship between risk aversion and ambiguity aversion. 

Bibliography:
Bradley, Richard, “Decision Theory: A Formal Philosophical Introduction”, https://personal.lse.ac.uk/bradleyr/pdf/Handbook%20-%20Decision%20theory%20(revised).pdf
Hansson, Sven-Ove, “Decision Theory: A Brief Introduction”, https://people.kth.se/~soh/decisiontheory.pdf

Calendario:
Dal 22 al 23 novembre 2025:
sabato 22 dalle 9 alle 12 e dalle 14.30 alle 17.30
domenica 23 dalle 9 alle 12 e dalle 14.30 alle 17.30
Aula S. Bruni