He uses abstract arguments to make his point. He uses imagined cases to show us that what we think matters actually doesn't. We only think so because we're confused. He says personal identity doesn't matter. If you think persons are souls, you're wrong. And when we think of concepts like selfish v. self-less we're actually not making a coherent distinction because really there is no self.

This book is mind-blowing. I'm still trying to wrap my head around it. Parfit seems to have solid arguments. He just reaches a conclusion that most of us are hesitant to accept.