 A related and much-discussed problem, the problem of the many, was raised by Peter Unger (1980) and Geach (1980). Basically, the idea is that with many, probably even most, physical objects, there are any number of equally compelling candidates for their borders, and hence their physical constitution. In the terms we’ve been dealing with here, there are any number of equally compelling candidates for being the referent of a singular referential term, like ‘that’, when that term is being used to target a physical object. Without some way of selecting one of these as somehow privileged, we might wonder whether we should really think of such terms as referring—unless,  that is, we are happy to accept that apparently-singular referential terms in fact refer to sets of objects, vague objects, or the  like.[16]