Starting the session, former CIA operative Valerie Plame Wilson calls for the complete elimination of nuclear weapons. “It’s a wake-up call we need.”

Michael Sandel: “We need to rediscover the lost art of democratic argument.”

Christopher “m00t” Poole: “I asked 4chan what I should say at TED. And I got 12,000 responses in about 24 hrs. But I can’t read to you anything they said.”

Kevin Bales: Ask ourselves: Are we willing to live in a world of slavery? #TED

Chris Anderson introduces Steward Brand and Mark Z. Jacobson to debate on nuclear power. His rules for the audience? “Cheering, booing, hissing are allowed.” Before and after the debate, the audience votes: how many are for nuclear power? How many against?

All photos: TED / James Duncan Davidson