The New York Times has an interesting piece on the variability of people’s personalities, tastes and opinions over time and how we tend to underestimate the amount we will change in the future:

when asked to predict what their personalities and tastes would be like in 10 years, people of all ages consistently played down the potential changes ahead. Thus, the typical 20-year-old woman’s predictions for her next decade were not nearly as radical as the typical 30-year-old woman’s recollection of how much she had changed in her 20s. This sort of discrepancy persisted among respondents all the way into their 60s. And the discrepancy did not seem to be because of faulty memories, because the personality changes recalled by people jibed quite well with independent research charting how personality traits shift with age. People seemed to be much better at recalling their former selves than at imagining how much they would change in the future.

This wouldn’t have come as any surprise to Montaigne, whose whole project was predicated on the idea of constant change in the self:

I am unable to stabilize my subject: it staggers confusedly along with a natural drunkenness. I grasp it as it is now, at this moment when I am lingering over it. I am not portraying being but becoming: not the passage from one age to another … but from day to day, from minute to minute. I must adapt this account of myself to the passing hour. (“On repenting”, Screech trans 908-9)

But how much this contradicts the central presupposition of much intellectual biography, which is to find as much consistency as possible among the attitudes and doctrines adopted by a person throughout their life.