Four striking things that McDowell says:
1. Cavell "concludes that the idea of seeing something as something is not helpful here because if we frame Diamond's thinking in terms of aspect seeing, we do not give proper weight to the fact that for her other animals simply are our fellows, not things we can see as our fellows if we can achieve an aspect switch" (pp. 127-128). But I suspect Diamond would accept the possibility that someone might fail to see an animal as a fellow being and then, perhaps quite suddenly, start to see it as one. And that the same thing could happen with a human being. Doesn't Scrooge come to see his employees differently, to see them as human beings? The duck-rabbit might not be helpful, because it seems too much like a toy or game, but I think aspect seeing is relevant (and I think Cavell recognizes this).
2. If "one views animals as Diamond does, one would have to see sending them to be turned into food, however friendly one's previous relations with them were, as a betrayal" (pp. 130-131). Maybe, but I wonder. Stephen Mulhall talks about the way animals are treated in the little house on the prairie stories. Must such farmers be regarded as betraying their animals if they take them to be slaughtered, or slaughter them themselves?
3. Costello's "response is over the top" (p. 134), and "does not give such questions [as in what sense factory farming is like the Holocaust] the care they need" (p. 131). This sounds a bit like saying that she needs to calm down. Which is understandable, but jars a little nevertheless.
4. A different poem would have been harder for Ted Hughes to write (p. 132). Would it? How easy or hard was the first one to write?