How old is too old to lead? How young is too young?
I have a simple heuristic. Competency is a function of 1) mental fitness and 2) experience, both of which have their own relationships to age. Using our intuition to map out roughly what each curve looks like, overlaying on a chart, and defining overall competence as the average, we end up with this simple but useful visual representation.
Fitness peaks around age 20-30, and although experience technically continuously increases, the practical utility of that experience peaks anyways around age 50-60. Afterall, what good is extra knowledge if you can’t readily remember and apply it?
As a result, competency steadily increases from birth right up until the sweet spot around age 40-50, at which point the minor degradation in fitness is more than made up for with increased experience. After 50, the continued degradation of fitness, less frequent new and useful experience, and declining memory all contribute towards a slow and steady decline in overall competence.
If it’s valid to have reservations about hiring 20-year-olds who lack experience and judgement, then it is just as valid to worry about hiring 70-year-olds in questionable states of mental fitness. It makes no sense to have a minimum age on the Presidency or any other role of importance without a corresponding maximum age. The average age of a US Senator is 64, with a range of 35-91. 91! Are you joking? The competency level of a 91-year-old simply cannot be argued to be beyond that of a teenager, at best. And nobody is talking about putting teenagers in the Senate…
Of course, this approach is an oversimplification. In some fields the ideal age is a bit younger or older, and the curves slope a bit less or more dramatically. And there will always be unique cases, those rare 75-year-olds who show no obvious signs of slowing down, and the occasional wise 35-year-old with experience beyond his years. But in general, the heuristic is very useful when we must make our decisions with imperfect information. I for one, only see doctors around the age of 40. That seems likely to me to be the peak of the competency curve in most medical fields. Why would I voluntarily choose otherwise?