² “Intuitively obvious” is among the most notorious weasel-phraess in mathematics; in some contexts, this has been called “proof by intimidation.” At its best, it means that the statement under discussion should, in fact, be seen to be true based on common sense. At its worst, it means that the writer thinks something is true, but has no idea how to show it and so is trying hard to pretend that the Emperor is well-dressed. We’ll use it (or something like it) ourselves from time to time; be sure to distrust us every time we do).