Your cat is a robot
Kripke’s claim is that if we discover some cat is a robot, we will not say “no cats exists.” We will in fact say, “Whoops. Looks like we were wrong about cats.” This is the epistemic sense in which it is “less necessary” than “bachelors are unmarried men.”
However, Kripke proposes “cats might turn out to be demons,” in the metaphysical sense. He puts “demon” and “animal” on the same ontological footing. He does this to say that if something is a demon, then it is not an animal. If something is an animal, then it is not a demon. But if these two kinds sit on the same level, when I propose that “cats might be demons” or “cats have always been demons,” suggesting that this paradigmatic instance is just “cat-like” or is a facade seems unfair. No, I mean to say “cats have always been demons and cats are a kind of demon–they have been all alone; they just gave the first blush of looking like animals.”
It seems like Kripke just stipulates the empirical matter but “animal” and “demon” would theoretically be contrasting classes. Kripke treats “demon” as if it were a something sitting on the same level as “cats” when he should be treating it as if it were contrasted against “animal.” There are many kinds of demon in various mythologies. Perhaps kinds of robots too: R2-D2, C-3PO, Data, the fancy ones of the future, etc.
Further, I do not see why Kripke admits talk of demons as if it were an empirical thing. He treatment of unicorns could be applied to demons. He’s argued that unicorns necessarily do not exist in the metaphysical sense. Thus, he’s argued that demons necessarily do not exist. To which mythology would we attribute our “demon” finding to? If we found cats-as-demons, we’d likely not even have a mythology because it’s likely non-existent that association of cat and demon (Ancient Egypt mythos?). But we have no way, in principle, to conclude that a cat is a demon. So it seems that, at best, Kripke’s conclusion is, given his treatment, that [if] cats are demons, then we could never find this out because we’d have no confirming evidence (epistemic sense). We might just be talking about fool’s demons, or the wrong story.
But the appeal to “myth,” an ancient story, is strong in Kripke. Unicorns, assumes Kripke, are mythical species. Further, so many stories are written about them. I fail to see how suggesting that the myths are wrong about the internal structure shows that no unicorns exist…it might simply show that unicorns in the way myth X, Y and Z conceive. But surely there’s a common attribute each unicorn of every myth shares. The “disparate descriptions” argument Kripke gives I think fails. Internal structure perhaps is a bit different.
I’m sure the argument is an easy one that follows that Aristotle wrote much of animals and surely they did exist, regardless of there being an account of their internal structure.