How to Make Good Decisions Fast

The fastest important decision that I ever made was to ask my present wife to marry me after I had known her for barely a week. She asked for 24 hours to think about it, and then said "Yes." Twenty years on, we are still happily married. Science is now producing reasons in support of our apparent impetuosity.

It is a science that was unknown in the days of Benjamin Franklin, who used "moral algebra" to make his decisions. "My way" he said "is to divide half a sheet of paper by a line into two columns; writing over on Pro, and over the other Con. Then, during three or four days consideration, I put down under the different heads short hints for the different motives. When I have thus got them all together, I endeavor to estimate their respective weights ... [and] I find at length where the balance lies."

The modern science of quick decision-making is called heuristics. It is concerned with finding simple rules for making good decisions in complex situations. One of its discoveries (proved in areas from weather forecasting to the prediction of high school dropout rates) is that there is often no need to assess the relative importance of different factors. Just drawing up lists of "for" and "against", and going with the longer list, can produce as good a result or better.

This is what Charles Darwin did when deciding whether to propose marry his cousin Emma. His original list is still on display at his home in the village of Down, England for all to see. The pros included companionship ("better than a dog, anyhow"), while the cons included the fact that he would have less money for books. The list of pros was longer than the list of cons, and Darwin duly proposed.

Darwin's procedure is now called "tallying." My wife Wendy and I each did our own mental tallying during that first frenetic week, and with the pros outweighing the cons and neither of us wanting to keep a dog. If we had followed Franklin's more complicated procedure we would probably still be trying to work out whether to get married or not.

"Tallying" allows quick decisions that can be surprisingly accurate. It can be used in many area of life (sometimes with caveats that I discuss in "The Perfect Swarm"), but it is not the only simple rule that the science of heuristics has come up with to help us steer our way through the complexities of life. There are nine others. Watch this space.