Our minds contain processes that enable us to solve problems we consider difficult. “Intelligence” is our name for whichever of those processes we don’t yet understand.
Some people dislike this “definition” because its meaning is doomed to keep changing as we learn more about psychology. But in my view that’s exactly how it ought to be, because the very concept of intelligence is like a stage magician’s trick. Like the concept of “the unexplored regions of Africa,” it disappears as soon as we discover it.
-- Marvin Minsky, The Society of Mind