Imagine a coffee shop full of people who laugh, sip lattes and dodge traffic with absolutely no inner experience. That philosophical zombie thought experiment opens an episode on the hard problem of consciousness, the distinction David Chalmers drew at a 1994 Tucson conference between the mechanistic easy problems and the question of why brain processes feel like anything at all. The hosts use a stubbed toe and a television with an invisible audience to illustrate the explanatory gap.

They then walk through the classic arguments, Thomas Nagel’s bat, Frank Jackson’s Mary in her black-and-white room, and the zombie conceivability argument that threatens physicalism, before giving the opposition its turn: Daniel Dennett’s stage magic, change blindness, Massimo Pigliucci’s category mistake and the comparison to vitalism. Scientific efforts like Crick and Koch’s neural correlates, integrated information theory and global workspace theory are weighed against Scott Aaronson’s pretty hard problem, and the episode closes on panpsychism, Colin McGinn’s cognitive closure and Chalmers’s 2018 meta-problem.

• Why Steven Pinker says the easy problems are as easy as curing cancer
• Does Mary learn something new when she sees a red apple for the first time?
• Logical entailment versus emergence: why a replica clock tells time but a replica brain might not feel
• Phi, the dark theater of global workspace theory and what they leave unexplained
• New mysterianism and the golden retriever that will never understand algebra