If this were true, how would it work?

wiseness is based on experience, so it is possible to be wiser than a younger generation, and simultaneously more intelligent than a previous one.

Nicely reasoned. However, I think Orwell's point was ironic. He isn't stating a fact beyond that each generation "imagines" it is a pinnacle of knowledge not by logic or imperial fact but simply out of PRIDE.

yeah, ego can be a doozie too

pride. so true, which explains a lot of the "back in my day" nonsense