The study of being qua being; or science qua science; or mathematics qua mathematics; or X qua X for any X.

Metaphysics.

Or as it is commonly referred to in computer science: function self-application. One example of which being the Y combinator (as in the name of this very forum).

I am applying a tautology in exactly the mathematical sense of a tautology; and I understand my construction just fine.

Had you been more charitable you would’ve addressed my argument; not your strawman of my argument.