It's the Achilles Heel of human beings. Neurolinguistic programming is one way of studying it. Billions of taxpayer dollars have poured into government coffers to learn how to exploit it.
Basically, words represent concepts, and concepts have boundaries, and boundaries are always fuzzy at some level - which is why they have to be defended. Who controls the boundaries of concepts, controls the words of those concepts. Who controls the words of those concepts, controls the behavior connected to those words.
Political Correctness IS that battle.
So—for Kucinich, the word-concept boundaries are so fuzzy as to be nearly non-existent?
He really does have that clueless look about him.