||The argument from vagueness is an argument for mereological universalism, the thesis that for any objects you like, there is an object which is the mereological fusion of those objects. Here is the main idea behind the argument: If we say that composition only sometimes occurs, then presumably there can be borderline cases of composition, that is, cases where it is vague whether the objects in question compose anything. But there can’t be borderline cases of composition. That’s because if it were vague whether some things composed something (say, a hammer head that is just beginning to be affixed to a handle) then it would be vague how many things there are (the handle, the head, and a hammer, or just the handle and head?). But we can make claims about how many things there are without using any vague language whatsoever. Consequently, those claims can’t be vague; they must have determinate truth values. So it can’t be vague how many things there are, in which case it can’t be vague whether composition occurs. So composition must be unrestricted.