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 ...