What is distinctive about understanding and interacting with other people? Our social relations are diverse in nature; people are encountered as strangers, the holders of certain social roles and statuses, neighbours, competitors, lovers, friends or family. And we interact with each other in all sorts of ways. Negotiating one's way along a busy shopping street alongside several hundred others, with the occasional exchange of nods, smiles or frowns, is very different from a free-flowing conversation with a good friend about assorted trivia. Playing a well-matched and familiar opponent at chess is far removed from answering a request for directions from a stranger. And, despite the diversity of social life, it seems that all our relations with people are somehow different in character from our interactions with inanimate objects. We do not ordinarily experience, understand and interact with each other in the same way that we do rocks, artefacts or (most) non-human animals.¹