Why is the answer e?

I would look to the end of the first paragraph to see what posners stated position is. The passage tells us that he is the most prominent critic of the movement offers some qualified support for it while still trying to refute the movement. So, we are looking for a case in which a critic offers qualified support for something that they still mostly oppose. This is exactly E, someone describes what is wrong with something while admitting it does have some positive aspects.