Matt Ridley, author of The Rational Optimist, talks with EconTalk host Russ Roberts about why he is optimistic about the future and how trade and specialization explain the evolution of human development over the millennia. Ridley argues that life is getting better for most of the people on earth and that the underlying cause is trade and specialization. He discusses the differences between Smith's and Ricardo's insights into trade and growth and why despite what seems to be strong evidence, people are frequently pessimistic about the future. Ridley also addresses environmental issues.