 The grammatical distinction is robust. Almost all speakers of a language agree on which sentences are grammatical and which are not. But philosophers disagree about the extent to which count nouns match up with sortals. The sentences “There are three red things on the shelf” and “Two objects collided” are definitely grammatical, so “red thing” and “object” are count nouns, but most philosophers argue that they are not sortals. For example, Hirsch and Wiggins think not because they claim that you cannot count red things or objects, even though the request to do so is grammatical. Others think that we can count red things but that the only two possibly correct answers are “infinitely many” and “none”. If nothing red is present there are no red objects. But if some red thing is present then so are the top half of it, and also the bottom half, each of which are counted as a red thing, And the three thirds giving us three more red things, and so on ad infinitum. Whether this is the best understanding of “thing” is disputed. We won’t linger over that debate just now, but the issue recurs later when we discuss sortals and concept acquisition in children.