Common sense is overrated (letter) |

Common sense is overrated (letter)

I see a lot of people talking about the importance of common sense. When people talk about commons sense, they mean intuition. Intuition is a technique that we humans have evolved over eons. When our ancestors roamed the plains of Africa hunting and gathering, intuition helped keep us alive by allowing us to quickly draw conclusions without having to analyze all the facts. Unfortunately, it can often lead to the wrong conclusions on everything from climate change to the safety of GMO foods. Our intuitions and common sense often tell us something that contradicts the evidence.

I was thinking about this the other day, when considering the Monty Hall Problem, a thought experiment in probability named after the host of the 1980's game show. The premise is pretty simple. A contestant chooses between three doors; one of which contains a valuable prize, and the other two contain worthless prizes such as a goat. What makes the problem interesting is that after the contestant chooses a door, the host will open one of the remaining two doors to reveal a goat, and then offer the contestant the chance to switch. The question is, should the contestant switch, and does it matter?

Common sense tells us that it doesn't matter. There are two remaining doors, and a prize is behind one of them. However, that is incorrect. In fact, the contest always has better odds of winning if they switch. The explanation is simple, yet many people still don't accept it. If the contestant doesn't switch, they have a 33% chance of winning the prize. A simple way of looking at it is, the contestant will only loose by switching if they picked the prize on the first try (33%.)

Unfortunately, common sense is a poor substitute for reason and evidence.

Timothy Faust