We don't want to get into a tit for tat with Iran,

If anyone offends you do not return tit for tat.

If you gaze long into an abyss, the abyss will gaze back into you.

We feel that these should not be tit-for-tat negotiations, this is something everyone should understand. Brazil and others are prepared to make some movement of our own and do everything that is necessary to move forward. This is an important step in the fight against poverty and I believe it is something that we must commit fully to achieving.

The danger is, if we're not very frank and strong about this, there will be tit-for-tat arrangements. You get into a situation where it becomes an epidemic.

What accounts for TIT fo TAT's roobust success is it's combination of being nice, retaliatory, forgiving and clear. It's niceness prevents it from getting into unnecessary trouble. It's retaliation discourages the other side from persisting whenever defection is tried. It's forgiveness helps retore mutual cooperation. And it's clarity makes it intelligible to th eother player, therby eliciting long-term cooperation. The Evolution of Cooperation, 1984