"And finally there's the question of why Tonia or Ione could be right in expecting themselves to Cooperate.  Why wouldn't they, when they got to the moment of finally writing the word Cooperate on paper, just throw away all the reasoning they did previously and write Defect instead?"

"Purely selfish agents, with nothing else in their utility functions, don't care about keeping promises they made to themselves."

"And finally there's the question of why Tonia or Ione could be right in expecting themselves to Cooperate.  Why wouldn't they, when they got to the moment of finally writing the word Cooperate on paper, just throw away all the reasoning they did previously and write Defect instead?  And wouldn't they know that, and be unable to say truthfully, to the other person reading them, that they'd Cooperate?"

"Purely selfish agents, with nothing else in their utility functions, don't care about keeping promises they made to themselves."