We really are creatures of a violent world, biologically speaking - watching violence and learning about it is one of our cognitive drives.

As individual people, embedded in our daily lives, of course we're interested in what makes one person different from another. We've got to hire one person and not another, marry one person and not another.

People have long assumed that violence is necessary for political change. Rulers never cede power voluntarily, the argument goes, so progressives have no choice but to contemplate the use of force to bring about a better world, mindful of the trade-off between a small amount of violence now and acceptance of an unjust status quo indefinitely.

Dominance in an adaptation to anarchy and it serves no purpose in a society that has undergone a civilising process or in an international system regulated by agreements and norms. Anything that deflates the concept of dominance is likely to drive down the frequency of fights between individuals and wars.

I think the reason that swearing is both so offensive and so attractive is that it is a way to push people's emotional buttons, and especially their negative emotional buttons. Because words soak up emotional connotations and are processed involuntarily by the listener, you can't will yourself not to treat the word in terms of what it means.

The connections I draw between human nature and political systems in my new book, for example, were prefigured in the debates during the Enlightenment and during the framing of the American Constitution.

A word is an arbitrary label - that's the foundation of linguistics. But many people think otherwise. They believe in word magic: that uttering a spell, incantation, curse, or prayer can change the world. Don't snicker: Would you ever say, 'Nothing has gone wrong yet' without looking for wood to knock?