The Smoking Lesion: A problem for evidential decision theory

This is part of a sequence titled "An introduction to decision theory". The previous post was Newcomb's Problem: A problem for Causal Decision Theories

For various reasons I've decided to finish this sequence on a seperate blog. This is principally because there were a large number of people who seemed to feel that this sequence either wasn't up to the Less Wrong standard or felt that it was simply covering ground that had already been covered on Less Wrong.

The decision to post it on another blog rather than simply discontinuing it came down to the fact that other people seemed to feel that the sequence had value. Those people can continue reading it at "The Smoking Lesion: A problem for evidential decision theory".

Alternatively, there is a sequence index available: Less Wrong and decision theory: sequence index

This is part of a sequence titled "An introduction to decision theory". The previous post was Newcomb's Problem: A problem for Causal Decision Theories

Alternatively, there is a sequence index available: Less Wrong and decision theory: sequence index

Do you see how this scenario rules out the possibility of me deciding rationally?

EDIT: In fact, let me explain now, before you answer, give me a sec and I'll re-edit

EDIT2: If the rational decision is to two-box, and Omega has set me to one-box, then I must not be deciding rationally. Correct?

If the rational decision is to one-box, and Omega has set me to two-box, then I must not be deciding rationally. Correct?

Now, assuming I will not decide rationally, as I know I will not, I need waste no time thinking. I'll do whichever I feel like.

You can substitute "the laws of physics" for "Omega" in your argument, and if it proves you will not decide rationally in the Omega situation, then it proves you will not decide --anything-- rationally in real life.

1thomblake16y

You left out some steps in your argument. It appears you were going for a disjunction elimination, but if so I'm not convinced of one premise. Let me lay out more explicitly what I think your argument is supposed to be, then I'll show where I think it's gone wrong. A = "The rational decision is to two-box" B = "Omega has set me to one-box" C = "The rational decision is to one-box" D = "Omega has set me to two-box" E = "I must not be deciding rationally" 1. (A∧B)→E 2. (C∧D)→E 3. (A∧B)∨(C∧D) 4. ∴ E I'll grant #1 and #2. This is a valid argument, but the dubious proposition is #3. It is entirely possible that (A∧D) or that (C∧B). And in those cases, E is not guaranteed. In short, you might decide rationally in cases where you're set to one-box and it's rational to one-box.