We have met Leviathan, and he is us

Take opening of _Leviathan_ and point out that what Clark is saying is that
much of what Hobbes attributes to the artificial man is true of the natural
one, as we find him.  We are products of our own art; this used to be a Marxist
theme.  It is also, of course, not at all incompatible with their being a
common human nature.  (On which point, from within the Marxist tradition,
see Geras.)

What Clark calls "Ramachandran's principle" is in fact Helmholtz's (though
not, I think, earlier).  Similarly the extended self can be found in
William James, extending even to the bank account.

Linguistically incomplete reductionism: the social environment _is_ biological.
Indeed, one could put this all very nicely in terms of Dawkins's "extended
phenotype", and I'm a little surprised that Clark doesn't.

Striking lack of the social sciences, beyond a bit about anthropology and
sociotechnical work.  There is, astoundingly, no mention at all of the vast
literature on collective choice and decision-making, or any of the studies
on institutions and organizations which view them as contrivances for
processing information and making decisions...

Most valuable part of the book is driving home the point that we've always been
like this, that this is not something new and unprecedented.  It's not even
obvious that what will happen in the near future with the web represents a
bigger change than what we (or rather, some of us) went through with literacy
and the state.  But we can think about what we're doing now!