If we could explain everything happening in your brain, would there still be something left to explain about you? Physicist Avshalom Elitzur thinks so—and argues that accounting for consciousness may require changing the laws of physics. In this lively conversation, Michael Shermer challenges Elitzur on why subjective experience should be anything more than a product of the brain, whether an AI could be conscious, and what a hypothetical human without consciousness would have to say about any of this.

Avshalom Elitzur is an Affiliate Professor at the Institute for Quantum Studies, Chapman University, and a senior researcher at Iyar, the Israel Institute for Advanced Research. He works in the foundations of quantum mechanics and is best known for the Elitzur–Vaidman bomb-testing problem.

Would World War II have happened without Hitler? Would someone else have built Apple without Steve Jobs? Jared Diamond joins Michael Shermer to ask how much history depends on particular people.

From Darwin’s discoveries to the rise of Christianity, Diamond considers when someone is truly irreplaceable, when someone else would have done much the same thing, and how we can tell the difference.

Jared Diamond is the Pulitzer Prize-winning author of the seminal million-copy-bestseller Guns, Germs, and Steel, which was named one of Time magazine’s best non-fiction books of all time, Collapse, a No. 1 international bestseller, and The World Until Yesterday, among other books. A professor of geography at UCLA and noted polymath, Diamond’s work has been influential in the fields of anthropology, biology, ornithology, ecology and history, among others. His new book is Profits, Prophets, Coaches, and Kings: (When) Do Leaders Matter?

How did 19 hijackers evade the world’s most advanced intelligence apparatus despite years of warnings? Twenty-five years after 9/11, journalist Gerald Posner joins Michael Shermer to explain the security failures that left America vulnerable. Those failures, compounded by government secrecy, have helped sustain suspicions that officials orchestrated the attacks or deliberately allowed them to happen.

What does the evidence show, and have we learned the right lessons?