If people were asked this question on a survey, I think the variations in responses would be significant and useful to know:
In general, people would give lower scores as they got older, but not always. The YouthBuild program (which we evaluated) serves disadvantaged adolescents and young adults. Before entering this 9-month program, participants predict that they will live to an average age of 40. Many believe that they already know the outlines of their lives. But upon completing the program, they think they will live to the age of 72: a 32-year increase (Hahn et al 2004). They now foresee decades of life that present unpredictable possibilities.
I agree with Kieran Setiya that “midlife” is best understood not as a span of years–say, ages 35-60–but as a subjective attitude to time that can occur at any age. Inspired by his book but departing a bit, I would measure midlife as a low score on the question shown above. By that definition, adolescents entering YouthBuild are already in midlife and even suffering from midlife crises. But for someone else, that state might never arise, or it might occur for the first time at age 90.
Is it good or bad to score high on this measure? That may depend on how well your life is going. If you expect to continue back-breaking labor for the rest of your life, still shackled to an uncaring partner, and suffering the regular deaths of loved-ones, you certainly would prefer not to be able to predict the rest of your life based on your story so far. But if you have retired in good health to a lovely seaside community, you may want nothing more than to run out the clock without seeing any unexpected changes to yourself or the people you care about. Priam had every reason to think that his life was a happy story until, as a very old man, he had to witness his hero son Hector being dragged dead around his besieged city.
I suspect we also vary in our subjective stances to change. For some people–almost regardless of their objective circumstances–predictability is comforting. But it is horrifying for others.
James Joyce published “The Dead” when he was 32. He had a long, dramatic, and hugely influential life ahead of him and surely couldn’t imagine that he’d become the Zurich-based author of Finnegans Wake by 1941. His protagonist, Gabriel, is also a “young man.” But I think “The Dead” is all about realizing that you know the whole course of your life. This is possible if you are a somewhat average bourgeois Dubliner, like Gabriel, or a budding international literary sensation, like James Joyce. Either way, to think you know your whole life-course is akin to being dead: you might as well just fast-forward to the end. That is the sense in which midlife is a depressing state rather than a comforting one.
I would predict that answers to this question would vary by age (but not in a lockstep correlation), by social circumstance (people with more opportunities will be less likely to think that they know their own futures) and by temperament.
Certain meditative experiences are intended to lower one’s score. For example, momento mori–meditating on death–is meant to remind you that you already know the important part of your story, how it ends. That is supposed to focus you on being pious. But Buddhism often reminds us that life is unpredictable, basically unstable, and that not being able to know the future should drive your attention to current experience. I vote for the latter although I am not very good at it.
Source: Hahn, A., Leavitt, T. D., Horvat, E. M., & Davis, J. E. (2004). Life after YouthBuild: 900 YouthBuild graduates react on their lives, dreams, and experiences. Somerville, MA: YouthBuild USA. See also Kieran Setiya on midlife: reviving philosophy as a way of life; nostalgia for now; rebirth without metaphysics.