Putnam on the Meaning of Natural Kind Terms

In "the meaning of 'meaning'," hilary putnam uses three "twin earth" examples to argue that natural kind terms do not have a sense. I argue that the first two only show that kind terms are like indexicals and that they are rigid designators but that this is compatible with having a sense. The third argument relies on a theory about the epistemological role of kind terms and the claim that there are no analytic truths about kinds that could arise from a sense