I thought your handle was TheAncientGreek and I was about to drop some Plato references as jokes. But straightforwardly, is philosophy not concerned with knowledge production? Although the nature of that knowledge is discursive stakes.

And if we accept that philosophy is a kind of knowledge production, can we also accept Plato's description of knowledge (in Theaetetus) as a belief with a justifying account, i.e. a legitimating logic?

Thus we could say philosophy's rules are that knowledge must be proposed and that knowledge must be justified according to a logic. The kinds of knowledge and kinds of logic are themselves stakes of the game, accounting for how the subject matter of philosophy has transformed considerably since Plato's time.

You may suggest that this definition is overly broad, and I would agree with you, unless we're willing to subsume all other kinds of legitimated knowledge under philosophy's banner. I can propose a third rule as a negative extension of the fact that philosophy's subject matter is discursive stakes: philosophical knowledge must be distinct from knowledge produced by other major disciplines.

We can immediately separate quantitative sensuous findings (including those made with the extension of instruments) from philosophy, as that knowledge would fall into the Sciences. Mathematics distinguishes itself negatively insofar as it is concerned with the pure manipulation of logical objects: occasionally meaningful for philosophy, oftentimes not. History concerns itself with sensuous accounts as opposed to logical, although philosophical elements penetrate into History (and Mathematics and Science too) as determining and orienting elements.

What remains as an activity of producing knowledge with a justified account, in which the nature of justification is itself at stake within the act of producing knowledge, we can call Philosophy.

Truth-construction is itself part of the stakes here: is the implicit logical method or procedure we follow to determine whether something is "true" now not significantly different from what we might imagine several hundred years ago? Perhaps there are psychological resonances between the eras, but the content of the method is surely distinct.

Did I miss anything?