Intelligence comes in many forms. I am a huge fan of Thomas Gardener’s theory of Multiple Intelligences.
My ex-husband knows nothing about politics, never finished college, and hasn’t read a book in years, but that man is the most incredible design engineer around. He can come up with an idea for a process, design and build the machine to make the process happen, get it up and running and trouble shoot the entire thing by himself. He is amazingly intelligent, just not in the traditional ways. I have two brothers with PhD’s and I do not consider either of them more intelligent than my ex, their minds just work differently.
I think it is impossible to come up with a single definition of intelligence. It is different in different people and one type of intelligence can’t really be called better than any other type. I think an awful lot of really bright people get lost in the shuffle because they don’t learn well with the traditional “sit and get” methods of teaching.