Philip Hoag examines doomsday scenarios and the various catastrophic events that could devastate civilization or cause human extinction. His analysis explores threats from nuclear war to asteroid impact and how multiple potential catastrophes could plausibly end civilization as we know it. Hoag discusses the probability of different doomsday scenarios and which threats present the most immediate dangers versus those that remain theoretical possibilities. The conversation covers how civilization's complexity and interdependence create vulnerability where failures in critical systems could cascade into societal collapse. He examines nuclear threats including accidental war, terrorism, and how proliferation increases the likelihood that nuclear weapons will eventually be used with catastrophic results. Hoag addresses natural catastrophes from supervolcano eruptions to pandemic disease and how such events have historically caused mass extinctions or civilization collapses. His presentation reveals how multiple threats exist simultaneously and how the cumulative risk across all potential catastrophes suggests civilization faces significant danger in coming decades. The discussion covers whether anything can be done to reduce doomsday risks or whether humanity's trajectory makes catastrophic outcomes increasingly probable. Hoag explores how to think about existential threats and whether awareness of dangers enables constructive preparation or merely increases anxiety about futures individuals cannot control. His analysis demonstrates how fragile modern civilization remains despite technological advancement and how multiple pathways could lead to catastrophic outcomes that few are adequately prepared to survive.