> Brains are not for rational thinking, linguistic communication, or perceiving the world.
Isn't this false?
Brains are for whatever brains are for, and if brains are thinking rationally (2+2 = 4), communicating linguistically (I'm typing this using language), and perceiving the world using senses than they are for those things just as much or as little as they are for or not for anything else. I suppose you can say something along the lines of "brains are for continuing survival and propagation of genes" as they author did which is fine, but it would make more sense to state that and try to prove it... Because how do we know that thinking rationally isn't what evolutionary drive is? How do we know that brains are evolved for survival? Survival for what? Gut bacteria? The earth (keep reproducing to keep organic material churning)? How do we know that the emergence of language and propagating that isn't what brains are for?
I think it's hard to really say what brains are for or not for. That's a deceptively difficult question and probably shouldn't casually throw out "brains are not for X".
-edit-
I also wouldn't take it for granted that brains or anything is for anything.
I do think we are "philosophical zombies" as someone else put it, but it's not a distinction that matters because whether we are or are not doesn't change anything. It's like accepting that you don't have free will - it doesn't change anything. You still go to jail if you rob someone (the interesting question comes from the morality of this actually IMO).
Consciousness is probably an evolutionary adaptation for increased cooperation - to that end it's a shared delusion (language allows us to become "more" conscious), but a useful one.
I'd posit that certainly all mammals are conscious (if they're not, then I'm not sure you can argue that anything is conscious besides yourself which is fine if you hold that view) and likely all animals are conscious, just a matter of degree of genetic expression. Panpsychism is tempting but if we wanted to say that rocks are conscious than I think we could set aside still different "levels" of conscious expression and draw meaningful distinctions - it's not a hill one has to die on.
Most of our work on consciousness that I've observed has historical religious baggage (not insulting religion here) with humans being at the center and "special" but if you strip that away I think it's pretty easy to see that we're not. Many scientists that I've seen or observed kind of have the God problem - which is that they're wrestling with a question or dilemma and supposing God is involved or exists and so it must be dealt with. Similarly in the study of consciousness it seems that we're supposing that humans are conscious to some special degree and trying to fit science to explain that - which is a faulty premise from the start.
/rant :)