Yes, obviously the argument is worked through a bit better in his book. But regarding the social contract, I'm more with CdM, on the assumption that when he says "we agree" he's using it as shorthand for "we accept perforce as the collective behaviour of our species, appreciate the logic, whether we agree or not, and find a way of functioning within the social contract". As a bleeding-heart liberal, the trouble I always have with libertarian arguments (at least as I've heard them advanced) is they are fundamentally unempathetic and callous. They also tend to massively overestimate the effectiveness of individual choice compared to collective effort and, critically, most people's reasoning ability. I'm not being snobby here, I just mean that there isn't time in a human's life to individually negotiate the details of their relationship, financial or otherwise, to everyone they deal with: hence trade unions, hence law, hence social conventions, hence - in short - collectivisation. Libertarianism to me is fine in smaller, simple communities than our current ones, but personally I'd rather have electricity, free internet infrastructure, safe dwellings and (when necessary) unemployment benefit than a basket of berries and nowt else.