> If I manage to stay out of trouble, it’s rarely because of knowing that much, but more because I’m relatively good at 2 other things: knowing what I don’t kno

> If I manage to stay out of trouble, it’s rarely because of knowing that much, but more because I’m relatively good at 2 other things: knowing what I don’t know, and knowing what I shouldn’t know. > [...] > I don’t know how to generalize the principle to make it explicit and easy to follow. Coming from mathematics that is what I would call using the right level of abstraction. If you want to prove 0 + 0 = 0 and you're getting tied up with stuff like how the direct sum of two Cauchy sequences should converge to the sum of the two limits then you're not working in the right level of abstraction. You're not supposed to know about Cauchy sequences yet if all you're given is the neutral element for addition. In some rare cases it can help knowing about sublevels of abstraction. Such as the difference between a general linear space and one equipped with an inner product. Just because you can make an inner product doesn't mean you should, and if you don't you'll find some arguments a lot easier because you're not distracted by stuff like adjoints and orthonormal basis vectors etc. (one side effect is that gradient descent no longer works, and you really ought to know why). You can do similar things by refusing to decide on a coordinate system.