Intelligence [...] is the ability to attain goals in the face of obstacles by means of decisions based on rational (truth-obeying) rules. (cited from HowTheMindWorks)
But most people know what intelligence is. And that's one of the problems. It is known by introspection and/or intuition. (I'm sorry, but do you mean "it is recognized by introspection etc." or "it is synonymous with introspection etc"?) It is usually hard for us to provide a definition, but easier to give examples. And then when we do start to pin it down we find that other people disagree with our definitions which we "know" to be correct. How can they be so stupid??
Then we try to work out what it means for a computer to be intelligent ...
I think that we will gradually find our way - with a bit of help from discussion about Artificial Intelligence - to a really good definition of intelligence.
And it will turn out that people aren't intelligent after all. -- DavidElsdon?
And so, we'll still be left with the same problem, but without a name to call it by.