If you follow the “genetic agent ontology”, and you grew up with a twin, and they (predictably) sometimes make a different decision than you, then you messed up. There is an objective sense in which the “genetic agent ontology” is incorrect, because de-facto you did not make the same decision, and treating the two of you as a single agent is therefore a wrong thing to do.
Yes, I agree. This is precisely my point; it’s a bad ontology. In the paragraph you quoted, I am not arguing against the algorithmic ontology (and obviously not for the “genetic ontology”), but against the claim that decision-theoretic performance is a reason to prefer one ontology over another. (The genetic ontology-analogy is supposed to be a reductio of that claim.) And I think the authors of the FDT papers are implicitly making this claim by e.g. comparing FDT to CDT in the Twin PD. Perhaps I should have made this clearer.
performance can be measured on
Yes, I think you can measure performance, but since every decision theory merely corresponds to a stipulation of what (expected) value is, there is no “objective” way of doing so. See The lack of performance metrics for CDT versus EDT, etc. by Caspar Oesterheld for more on this.
CDT in the classical Newcomb’s problem is delusional about it definitely not having copies of itself
(The CDTer could recognize that they have a literal copy inside Omega’s brain, but might just not care about that since they are causally isolated. So I would not say they are “delusional”.)
Yes, I agree. This is precisely my point; it’s a bad ontology. In the paragraph you quoted, I am not arguing against the algorithmic ontology (and obviously not for the “genetic ontology”), but against the claim that decision-theoretic performance is a reason to prefer one ontology over another. (The genetic ontology-analogy is supposed to be a reductio of that claim.) And I think the authors of the FDT papers are implicitly making this claim by e.g. comparing FDT to CDT in the Twin PD. Perhaps I should have made this clearer.
Yes, I think you can measure performance, but since every decision theory merely corresponds to a stipulation of what (expected) value is, there is no “objective” way of doing so. See The lack of performance metrics for CDT versus EDT, etc. by Caspar Oesterheld for more on this.
(The CDTer could recognize that they have a literal copy inside Omega’s brain, but might just not care about that since they are causally isolated. So I would not say they are “delusional”.)