They’re not necessarily impossible. If you have genuine reason to believe you can outsmart Omega, or that you can outsmart the near-copy of yourself in PD, then you should two-box or defect.
But if the only information you have is that you’re playing against a near-copy of yourself in PD, then cooperating is probably the smart thing to do. I understand this kind of thing is still being figured out.
They’re not necessarily impossible. If you have genuine reason to believe you can outsmart Omega, or that you can outsmart the near-copy of yourself in PD, then you should two-box or defect.
But if the only information you have is that you’re playing against a near-copy of yourself in PD, then cooperating is probably the smart thing to do. I understand this kind of thing is still being figured out.