Steven Pinker, an experimental cognitive scientist and professor of psychology at Harvard. He has been named by Time Magazine as one of the 100 most influential people in the world today. 

He joins Krishnan to discuss his new book, ‘Rationality: What It Is, Why It Seems scarce, Why It Matters’ which is billed as a user's guide to rationality during an epidemic of unreason.

Producer: Nina Hodgson