Moving right along, a couple of points about Laura Schroeter’s paper Gruesome Diagonals. I think this is what set of the nit-picking. I see people bashing 2Dism, I have to respond. And I respond in the best way I know how – by ignoring the substance of the argument and looking for the most trivial points to find. (It’s fun blogging some days.)

On page 14, Laura says that ‘renate’ and ‘cordate’ are co-extensive in all biologically similar worlds. I was trying to find a formal definition of these in order to see whether this is right, not realising that the terms are a philosopher’s invention. (Quine’s, to be precise.) Learn something new every day. Though I think they’re in wide enough use now that the OED should include them.

So I don’t know the formal definition, but I take it they are properties of animals, and they are defined such that for all x x is a cordate iff x has a heart, and x is a renate iff x has kidneys. (I think this is the definition.) Well those are clearly not co-extensive if we take the ‘s’ at the end seriously – I know some cordate with only one kidney, who are hence not renates. But that’s getting ridiculous.

Let’s imagine that I, in the interest of science, take a small defenceless rat, and pull out its heart. We’ll now have a dead rat, and a bit of a mess, but I think we’ll still have a renate. The dead rat still has kidneys, no? So there’s another counterexample to the co-extensiveness thesis.

Finally, and this one is meant a little more seriously than the previous two, some patients these days get fitted with artificial hearts. They are renates who are not cordates, are they not?

I can’t remember what point the cordate/renate example was meant to make anyway, so I can’t tell whether I’ve refuted it by these little games. Somehow I doubt that I have refuted anything here, but you never can tell.