We are social primates, for whom language-mediated co-operative thinking (‘co-cognition’) is a central element of our shared life. Psychological concepts may be illuminated by appreciating their role in enriching and improving such co-cognition — a role which is importantly different from that of enabling detailed prediction and control of thoughts and behaviour. This account of the nature of psychological concepts (‘co-cognitivism’) has social anti-individualism about thought content as a natural corollary. The combination of co-cognitivism and anti-individualism further suggests that, in (...) addition to the familiar first person authority with which we ascribe thoughts to ourselves, there may also be something deserving the name ‘second person authority’. (shrink)