When one thinks of a hard subject, often what comes to mind are ‘STEM’ subjects, (e.g. math and physics), not the humanities, which are assumed to be more subjective and less rigorous. But such impreciseness also makes the humanities harder in some ways. Objectivity creates boundaries and rules, which can be generalized and repeated. A hypothesis can be falsified. A conjecture can be disproven with a counterexample. As hard as calculus can be, there are immutable rules that underly it, which can be taught and reproduced. There is only a single ‘chain rule’; the concept is culturally invariant, even if the notation occasionally differs.
The rules-based nature of mathematics provides a more structured path to competency. Mastery of writing requires not only a lifetime’s worth of vocabulary acquisition and the ability to use it appropriately, but broader cultural literacy that simply can’t be taught.
I agree (the entire twitter-thread is excellent). Having done both, math is more rule-based, although it does require the occasional epiphany to clear an impasse.