The argument that non-human animals do not possess some vague set of traits that make humans the only species worthy of being classified as ‘people,’
Metacognition. It’s just metacognition. Not vague in the slightest. You can argue that it isn’t a good criterion, but it’s a very clear one.










Gravity is not a theory. It’s a law. We don’t know enough about gravity to make a theory for it.