One nice formulation of the reference class for the DA is "observer-moments that think about the DA". Maybe there are even better formulations.

And that might even concievably be a good formulation. That is NOT obviously a bad argument. It may or may not be a good argument, but it's not obviously bad. I can't just plug in a word-substitution and get the same argument to say something different without breaking the argument.

It's also not the argument you presented me with. You presented me with the argument formulated over humans. Which is obviously a bad argument.

About Bob: the question is whether the DA constitutes valid evidence, not whether it's complete evidence. Of course the gun is stronger. But if you were in a state of near-total ignorance, would the DA not sway you even a little bit?

No, because reference classes that are identical with regard to the present, ie. Humans and Cyborgs. Humans. Humans who live their entire life on Earth. Can be very different. And hypothetical ignorant me would be able to come up with such reference classes, unless hypothetical ignorant me lives in a very very simplified world.

In an extremely simplified world, with my only knowledge being that I am Mr. 989,954,292,132, I might buy into the doomsday argument as regards Mr.s

About Sean: most adults who consider Sean's "adult doomsday" variation will turn out to be right. You have simply cherry-picked a counterexample. If such tactics were valid for breaking the DA, they would also break all probabilistic reasoning, which isn't what we want.

True, my apologies, that was an obviously bad argument, and I missed it.