Full Idea
TIT FOR TAT threatens 'Do unto others as you would have them do unto you - or else!'.
Gist of Idea
Do unto others as you would have them do unto you - or else!
Source
William Poundstone (Prisoner's Dilemma [1992], 12 'TIT')
Book Reference
Poundstone,William: 'Prisoner's Dilemma' [OUP 1992], p.240
A Reaction
Essentially human happiness arises if we are all nice, but also stand up firmly for ourselves. 'Doormats' (nice all the time) get exploited. TIT FOR TAT is weak, because it doesn't exploit people who don't respond at all.