That's not really what I said, though. The point about an individually rational decision (where it does not align with the group rational decision) is that it

That's not really what I said, though. The point about an individually rational decision (where it does not align with the group rational decision) is that it is less good for the group than the group rational decision. So if all your individuals in the group make the individually rational decision, the group as a whole suffers (and indeed, each individual is overall worse off than if everyone had taken group rational decisions). We're not talking here about forcing people to do anything - we're saying what is noble, and what is not. My argument is that nobility is taking the group rational decision. This may sometimes mean sacrificing one's own immediate desires.