Invert the question, if math is just another grammar, and all grammars adhere to

Invert the question, if math is just another grammar, and all grammars adhere to the universal grammar (language), then the unification of the grammars is possible if we universalize that grammar by reforming each discipline into one universal logic of universal commensurability. If so, then why should the mathematicians any more than the scientists of philosophers base their foundations on that which is false and produces externalities? So in other words, what does math as it is practiced have to do with everything else?

(And yes I realize that this is a subject that is difficult to grasp without rather exhaustive studying the consequences of ‘bad math’. I mean, Descartes restores the european tradition and Einstein and Bohr devolve it again? That’s only possible because the foundations are sets rather than grammars.)

Reply addressees: @matterasmachine @Plinz