> From that point you can go in at least two directions, one would be something like a Turing test of the fake cow... beyond a certain point it’s a matter of semantics as to whether it’s a real cow or not, or you could say that your “justified true belief” had to apply to the total state of the field. If you believed there was both a cow model and a cow behind it, that woukd be justified, but the existence of the cow behind the model would not justify incorrect belief that the model was a real cow, in the sense of not admitting uncertainty over the things you see.

You're replacing the model it was criticizing with a different model and then saying that it doesn't say anything interesting about your model, so it's not interesting. It's not an argument that knowledge isn't possible, it was an argument against the traditional definition of knowledge as it was almost universally understood at the time.