Yeah, it's odd that Keirsey is a behaviorist who claims to be only interested in observable behavior patterns, and yet, he does end up making quite a lot of assumptions about the reasons behind what people do, including what people are --or aren't-- supposedly thinking.
I've seen Fi
equated with the NF temperament more times than I can remember. Ditto with Ti and the Rational temperament. That's too bad, because understanding those functions
apart from temperament really helps explain why ISFPs and ISTPs are the way we are.
By the way, I know I criticize David Keirsey a lot, but on the other hand I respect him for what he says about intelligence being "doing things well under varying circumstances." I'm a big fan of Howard Gardner's theory of multiple intelligences, and I believe that everybody in this world is dumb in some ways and brilliant in other ways, and that the key to appreciating people is to find out what ways they're smart in. So kudos to him for that.