I am studying Ramsey's 1925 paper Universals, and he states that "Socrates is wise", "Plato is wise", etc. are propositions of the form "x is wise", yet "Neither Socrates nor Plato is wise" is not. It is instead of the form "$\phi$ wise" where $\phi$ is a variable.
Why is this? I don't really understand it. Is it because "Neither Socrates nor Plato" is not of level 0 (like a single proper name) but level 1 (like the proposition "x is wise" itself) so cannot be "substituted into" a level 1 expression?
Thanks