Human beings have evolved to cooperate with each other which is why our dominant rule of thumb is the rule of tit for tat. We are wired to cooperate and help a fellow human being unless that other human being refuses to cooperate with us. In such a case, we retaliate. Tit for tat is a relatively good strategy and can be said to be optimal in some strategy games. But there is dark side to employing this strategy. We have developed a habit of saying "yes" to a request without really assessing the opportunity cost of agreeing to do something for someone else so much so that some people can spend their entire lives just trying to please other people. So Charlie Munger of the Berkshire Hathaway fame suggests giving the "five-second no". He would think about a random request for five seconds and then just say no. Some ......