In a recent post, a rule of thumb has been given to tell subject and predicative apart, which, initially, because of both being in nominative, I thought would impossible. Namely:
It seems legit. However, it strikes me that you have to appeal to sense-making, while the syntax should be able to detect the subject by itself, as is, for instance, in the following two sentences:
Gras isst der Hase.
Den Jäger isst der Hase.
In both sentences the noun Hase is the subject. That has nothing whatsoever to do with making sense.
Is there an alternative rule to (*) that is independent of semantics?