One thing I noticed about this example is that the claim "All cats are mammals. Garfield is a cat." doesn't appear on its surface to be a conditional relationship the way the second example with downtown restaurants does. Just a note for consistency since this example of "X is Y." has been used elsewhere to demonstrate when something ISN'T a conditional relationship. I guess that's the point J.Y. is trying to make here but it honestly just makes me more confused because intuitively you can tell these arguments are different in form.