But then just today I stumbled again, this time across the page in Wikipedia describing the Big 5 Personality Traits. I was surprised mainly because I'd never heard of them. I don't read a lot about psychology, but still, I do read a fair amount about a wide range of topics, and I'd have thought that a concept that's this fundamental and this well researched would have filtered down to me.
It describes five traits that can be used to measure the main aspects of a person's personality. I believe this scheme has validity because the article describes the way that it came about was through mathematical analysis (factor analysis) of empirical data. Factor analysis is an extremely powerful technique that can yank a small number of relevant variables (factors) out of a large pool of correlated data.
I'm guessing that this Big 5 theory, like IQ, is controversial, and for many of the same reasons. People hate to think that human beings are not "blank slates" -- that there are inherent things about us that make us different from one another. "All men are created equal" is a lovely sentiment, but for any particular trait, it's simply not true. It's obviously not true for any physical trait (height, shoe size, etc.). Why should it be true for psychological traits? It seems obvious to me, having lived as long as I have, that people really do have personalities that persist over their lives, and that are extremely resistant to change. I'm not saying I think people can never change, just that it's damn hard, and it's harder to change some aspects of oneself than others.
For what it's worth, here are the results of on online test that I just took. I was surprised (and oddly disappointed) by the results. I would have thought that I'd have scored higher on all of openness, conscientiousness, and agreeableness. The last trait is "neuroticism", and I scored about where I would have expected there.
Taking this test doesn't change a thing about me, of course, but somehow, it changes everything.