Seeing the unseen

“A man has two siblings. I am not going to reveal their gender, but I will tell you that he has at least one sister. What is the probability that he also has a brother?”

If you intuitively answered 50% (or less) you are not seeing the entire picture. If you answered 2/3, then congratulations, you got it.

Easy explanation: The gender of two siblings has four possibilities or outcomes: (Big brother, little brother), (Big sister, little sister), (Big brother, little sister), (Big sister, little brother). Three of those outcomes (the last three) has 1 or more sisters. Out of those 3 outcomes, 2 includes a brother, hence the answer is 2 out of 3.

This kind of problem is what Schumacher refers to as a convergent problem. Convergent problems asymptotically converge towards a solution. This means that ultimately, there are no unknowns and it can be solved. Science has a long tradition of dealing with convergent problems. Real life, however, are full of divergent problems that have no closed solutions. Witness what happens when those two worlds collide (rocket scientists on Wall Street). Problems with unknown unknowns are problems that must be lived through. It is problems such as trying to arrange for optimal happiness by going from poor to rich with the self-defeating outcome that this strategy ultimately makes you rich and thus no longer a user of the happiness-strategy. It is problems such as trying to run a country, a company or even your life.

People can be given a strategy and they can implement such a strategy in their life. However, a strategy for a divergent problem is not a solution. It is just a suggestion of tactics.