 The important point is that, even in the case where I am given that \(3^2 + 4^2 = 5^2\), I ought not to say ‘\((\exists x, y, z, n) (x^n + y^n = z^n)\)’, since taken extensionally that’s meaningless, and taken intensionally this doesn’t provide a proof of it. No, in this case I ought to express only the first equation. (PR §150)