You're given the option to torture everyone in the universe, or inflict a dust speck on everyone in the universe. Either you are the only one in the universe, or there are 3^^^3 perfect copies of you (far enough apart that you will never meet.) In the latter case, all copies of you are chosen, and all make the same choice. (Edit: if they choose specks, each person gets one dust speck. This was not meant to be ambiguous.)
As it happens, a perfect and truthful predictor has declared that you will choose torture iff you are alone.
What do you do?
How does your answer change if the predictor made the copies of you conditional on their prediction?
How does your answer change if, in addition to that, you're told you are the original?
No it doesn't. It assumes a "perfect predictor" is what it is. I don't give a damn about evidence - we're specifying properties of a universe here.
CDT assumes causality makes sense in the universe. Your hypotheticals don't take place in a universe with the kind of causality causal decision theory depends upon.
In the case of a perfect predictor, yes, smoking specifies which gene you have. You don't get to say "Everybody who smokes has this gene" as a property of the universe, and then pretend to be an exception to a property of the universe because you have a bizarre and magical agency that gets to bypass properties of the universe. You're a part of the universe; if the universe has a law (which it does, in our hypotheticals), the law applies to you, too.
We have a perfect predictor. We do something the perfect predictor predicted we wouldn't. There is a contradiction there, in case you didn't notice; either it's not, in fact, the perfect predictor we specified, or we didn't do the thing. One or the other. And our hypothetical universe is constructed such that the perfect predictor is a perfect predictor; therefore, we don't get to violate its predictions.
You said "you shouldn't smoke", which is a decision-theoretical claim, not a specification. It's consistent with EDT, but not CDT.
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