When we hear or read a sentence, we are aware more or less instantaneously of what it means . Our minds compute the meaning somehow, on the basis of the words that comprise the sentence. But the words alone are not enough . The sentence meanings we establish are so precise that they could not be arrived at by just combining word meanings haphazardly . A haphazard word combiner could misunderstand (1) as meaning that all bears love; it could interpret (2) as meaning that pigs fly and rabbits can't .