The nature of knowledge

Inhis latest book, When Everyone Knows That Everyone Knows, Harvard cognitive scientist and psychologist, Steven Pinker, takes us on another profound journey into the human mind, a subject that he has explored in other celebrated books, including How the Mind Works, The Lan- ‘guage Instinct and Rationality.

- SHYAM SARAN

The present work puts forward a framework for dissecting the nature of knowledge, from howits diffusion determines the choice a couple makes ofa rendezvous location to how it may trigger an overwhelming popular revolution. Dr Pinker makes a crucial distinction between private knowledge, say, X, which resides only in anindividual’s mind andcommon knowledge, where everyone knows X, and everyone knows that everyone knows X, and so on ad infinitum. Whatis significant here is that it is common knowledge that enables individuals to coordinate their actions and collaborate for mutual gains. Communities, from atribe toa nation and on toa multilateral institution, collaborate on the basis of common knowledge, which providesa consensual basis for collective action.

DrPinker introduces another important concept, conventions, in elaborating, how common knowledge works. Conventionsare arbitrary rules ofbehaviour that become widely accepted because they are common knowledge. They enable coordinated activity. For example, driving on the left side of the road is the convention in several countries including our own, but it is entirely arbitrary and could well have been the opposite. But since everyone in India knows that everyone knows that everyone knows which side to drive on, it serves as common knowledge and enables safe driving.