 Putnam’s Division of Linguistic Labor may be thought of as furnishing an epistemological argument. Putnam’s idea is that the referent of a term used by some individual may be fixed not by their own knowledge or beliefs, but rather by the knowledge of certain experts to whom that individual defers. Since aluminium and molybdenum are different kinds, then according to descriptivism there should be some a priori knowable features that will distinguish between them for anyone who is capable of using ‘aluminium’ to refer to the one kind and ‘molybdenum’ to the other kind. Likewise there should be some mental difference between a speaker in the actual world who uses ‘aluminium’ to refer to aluminium and a speaker in another world, where the instances of aluminium and molybdenum are swapped (pans and cans are made of molybdenum there), who uses ‘aluminium’ to refer to molybdenum. But, says, Putnam, no such difference need exist: ordinary speakers have these differentiated referring capacities without any difference in knowledge of the referents. That is because those referential capacities are parasitic on those of the experts who do have the required discriminating knowledge (Putnam, 1975b, 228). Their knowledge fixes the referents of their use of ‘aluminium’ and ‘molybdenum’. Our deference to them as those people who could tell us which things are aluminium and which are molybdenum, means that our referents of ‘aluminium’ and ‘molybdenum’ are the same as theirs.