Phil 663: Probability and Decision Theory

The manuscript workshopped in this seminar was published in 2026 as The Philosophical Foundations of Bayesianism: An Opinionated Introduction (Routledge).

Time: Monday/Wednesday, 3:30-4:45 pm

Location: YMCA 401

Instructor: Kenny Easwaran

Office: YMCA Building 314, 979-847-6128

Office Hours: Monday/Wednesday, 4:45-5:45, or by appointment.

Over the past century, a great number of philosophers (and psychologists, economics, computer scientists, and others) have become interested in using mathematical tools to help understand the concepts of epistemology. In this class we will learn the basics of using some of these tools (focusing on probability and decision theory, though with some mention also of epistemic logic), and discuss both the history of their use and current topics related to them. This will include why formal epistemologists have focused on a notion of belief that comes in degrees, the way that these graded beliefs and desires play a role in governing action, and the contrasting roles of truth, evidence, and practical success in guiding belief.

Students should have taken a logic class before, and should have some comfort with high school algebra, but all other mathematical material will be covered in the class.

Each week we will be reading and discussing some primary texts from the relatively recent philosophical literature, and drafts of a manuscript that I am writing. One thing that will be particularly helpful to me is if you can let me know any comments, questions, unclarities, typos, etc. that you find in reading my manuscripts! Some issues will be things I can fix quickly, while others will spark important and interesting class discussions that may lead me to rewrite relevant sections.

For disability accommodations, please contact Disability Services so they can let me know what sorts of accommodations are appropriate.

Remember, an Aggie does not lie, cheat, or steal, and does not tolerate those who do. For further information, see the Aggie Honor System Office.

Aug. 31, Sept. 2; Sept. 7, 9

Required reading:

• For Sept. 2 - Bruno de Finetti, (1931, translation 1989) “Probabilism” (original Italian)
• For Sept. 7 - Keith Frankish, (2009) “Partial Belief and Flat-Out Belief”
• For Sept. 9 (class starts at 4 pm) - My draft of Chapter 1

Supplementary reading:

• Richard Jeffrey, (1970) “Dracula Meets Wolfman: Acceptance vs. Partial Belief”
• Lina Eriksson and Alan Hájek, (2007) “What are Degrees of Belief?”

Sept. 14, 16; Sept. 21, 23

• For Sept. 14 - Frank Ramsey, (1926) “Truth and Probability”
• For Sept. 16 - David Christensen, (2001) “Preference-Based Arguments for Probabilism”
• For Sept. 21 - Lara Buchak, (2013) “Risk and Tradeoffs”
• For Sept. 23 - My draft of Chapter 2

Supplementary reading:

• Bruno de Finetti, (1937) “Foresight: Its Logical Laws, Its Subjective Sources” (esp. chapters 1, 2)
• Donald Davidson, (1974) “Belief and the Basis of Meaning”
• David Lewis, (1974) “Radical Interpretation”
• David Christensen, (1996) “Dutch Book Arguments Depragmatized”
• Lara Buchak, (2014) Risk and Rationality (esp. chapters 1, 2)
• Kenny Easwaran, (2014) “Decision Theory without Representation Theorems”

Sept. 28, 30; Oct. 5, 7

• For Sept. 28 - William James, (1896) “The Will to Believe” (here or here or here, e.g.)
• For Sept. 30 - James Joyce, (1998) “A Non-Pragmatic Vindication of Probabilism” (focus on the first half)
• For Oct. 5 - Hilary Greaves, (2013) “Epistemic Decision Theory”
• For Oct. 7 - My draft of Chapter 3

Supplementary reading:

• William Clifford, (1877) “The Ethics of Belief”
• Kenny Easwaran and Branden Fitelson, (2012) “An ‘Evidentialist’ Worry about Joyce’s Argument for Probabilism”
• Richard Pettigrew, (2013) “Accuracy and Evidence”
• Michael Caie, (2013) “Rational Probabilistic Incoherence”
• Kenny Easwaran, (2015) “Dr. Truthlove, or: How I Learned to Stop Worrying and Love Bayesian Probabilities”
• Kenny Easwaran and Branden Fitelson, (2015) “Accuracy, Coherence, and Evidence”
• Richard Pettigrew, (forthcoming) “An Improper Introduction to Epistemic Utility Theory”
• Ben Levinstein and Jason Konek, (forthcoming) “The Foundations of Epistemic Decision Theory”

Oct. 12, 14; Oct. 19, 21, 26

• For Oct. 12 - Maya Eddon, (2013) “Quantitative Properties”
• For Oct. 14, 19 - Luce, Krantz, Suppes, Tversky, (1971) Theory of Measurement, Chapter 1

This is very technical material - we will go over it paragraph by paragraph in class - For Oct. 21 - Lyle Zynda, (2000) “Representation Theorems and Realism about Degrees of Belief” - For Oct. 26 - My draft of Chapter 4

Supplementary reading:

• The Leibniz/Clarke Correspondence (1715) - translation
• Sections 2.5, 2.6 (pp. 76-98) of Fred Roberts, (1985) Measurement Theory
• John Bigelow and Robert Pargetter, (1988) “Quantities”
• Chris Meacham and Jonathan Weisberg, (2011) “Representation Theorems and the Foundations of Decision Theory”

Oct. 28

• For Oct. 28 - My draft of Chapter 5

Supplementary reading:

• Kenny Easwaran, (2014) “Regularity and Hyperreal Credences”

(Nov. 2, 4 - I will be out of town)

Nov. 9, 11; Nov. 16

• For Nov. 9 - David Christensen (1991) “Clever Bookies and Coherent Beliefs”
• For Nov. 11 - Bas van Fraassen, (1995) “Belief and the Problem of Ulysses and the Sirens”
• For Nov. 16 - My draft of Chapter 6

Supplementary reading:

• Paul Teller, (1973) “Conditionalization and Observation”
• Bas van Fraassen, (1984) “Belief and the Will”
• Hilary Greaves and David Wallace, (2006) “Justifying Conditionalization: Conditionalization Maximizes Expected Epistemic Utility”
• Sarah Moss, (2015) “Time Slice Epistemology and Action Under Indeterminacy”

Nov. 18; Nov. 23

• For Nov. 18 - Ian Hacking, (1967) “Slightly More Realistic Personal Probabilities”
• For Nov. 23 - My draft of Chapter 7

Nov. 30, Dec. 2; Dec. 9

• For Nov. 30 - Miriam Schoenfield, (2014) “Permission to Believe: Why Permissivism Is True and What It Tells Us About Irrelevant Influences on Belief”
• For Dec. 2 - Nicholas Tebben, (2013) “Peer Disagreement and the Limits of Coherent Error Attribution”
• For Dec. 9 - My draft of Chapter 8