Concrete paths inherit from pure paths - this would be quite strange using antonyms. This isn't like an "abstract" base class. It's a full class on its own, which is extended by another.

Anyway, I think it's meant to be "pure" like pure functions, generally having no side effects or external inputs.

https://en.wikipedia.org/wiki/Pure_function

i think so too. like it says in the docs: "Regardless of the system you’re running on, you can instantiate all of these classes, since they don’t provide any operation that does system calls." http://docs.python.org/3.4/library/pathlib.html#pure-paths