after cooperating tomorrow as being a promise,

彼此合作的前景是大好的
and the value of the relationship after cheating as being a threat,

而相互欺骗的后果是不堪设想的
we need these promises and threats to be credible.

那么我们需要前景和恶果是真实存在的
We need to actually believe that they're going to happen.

我们得相信这些确实是会发生的
And one very simple area where we saw that ran immediately into problems

而且有个很简单的道理如果这种关系
was if this repeated relationship, although repeated, had a known end.

有一个已知的终点就会产生问题的
Why did known ends cause problems for us?

为什么已知的终点会产生问题呢
Because in the last period,

因为在最后一次的时候
in the last period of the game we know that

在博弈的最后我们都知道
whatever we promise to do or whatever we threaten to do,

不管我们是信守承诺还是相互欺骗
in the last period, once we reached that last period,

一旦我们走到了博弈的最后
in that sub-game we're going to play a Nash equilibrium.

在那个子博弈中我们就要达成纳什均衡