Alexander Pruss's Blog

Consider a choice between two wagers on a fair coin: W 1 : on heads, you get $1 if you are perfectly rational and $3 if you are not W 2 :...

Recently, I found myself puzzled by the difficulty in applying “classical” evidential decision theory to a perfectly rational agent. The pr...

Good’s Theorem basically says that a utility-maximizing agent can expect to make decisions that are at least as good if they get more inform...

Suppose I am perfectly rational in the decision theoretic sense. A coin is about to be tossed, and I will get five dollars on heads ( H ) an...

Suppose there is an infinite set of people, all of them worth saving, and you can save some subset of them from drowning. Can you assign a u...

Suppose infinitely many people independently roll a fair die. Before they get to see the result, they will need to guess whether the die sho...

Warning: I worry there may be something wrong in the reasoning below. Causal Decision Theory (CDT) and Epistemic Decision Theory (EDT) tend...

Suppose there are two opaque boxes, A and B, of which I can choose one. A nearly perfect predictor of my actions put $100 in the box that th...

Here’s a plausible immediate regret principle: It is irrational to make a decision such that learning that you’ve made this decision immed...

Suppose I am choosing between options A and B . Evidential decision theory tells me to calculate the expected utility E ( U | A ) given th...

In my last couple of posts, starting here , I’ve been thinking about comparing the epistemic quality of experiments for a set of questions. ...

Suppose that there is a simple majority election, with two candidates, and there is a large odd number of voters. Suppose polling data makes...

A generous patron makes an offer to you. You are to pick out a positive integer n and you will get 2 n units of value. You have the abilit...

Suppose we have two infinite collections of items L n and R n indexed by integers n , and suppose we have a total preorder ≤ on all the it...

Alice is confused about the nature of practical rationality and asks wrong philosopher about it. She is given this advice: For each of you...

Once again let’s suppose that there are infinitely people on a line infinite in both directions, one meter apart, on positions numbered in m...

This is all largely well-known, but I wanted to write it down explicitly. The von Neumann–Morgenstern utility theorem says that if we have a...

Suppose we neglect events with probability less than ϵ for some small ϵ  > 0 . Let’s suppose two independent random things have happened...

Let B t be a one-dimensional Brownian motion, i.e., Wiener process , with B 0  = 0. Let’s say that time 0 you are offered, for free, a game...

I’ve recently been troubled by cases where you are sure to regret your decision, but the decision still seems reasonable. Some of these case...