Catechism 101: The Argument from Motion

Catechism 101: The Argument from Motion

Author: Dr Caitlin West August 17, 2026 Duration: 13:15

In this episode, we explore St Thomas Aquinas’ First Way, also known as the Argument from Motion. This is one of the most influential philosophical arguments for the existence of God.

Building on our introduction to cosmological arguments, we unpack Aquinas’ reasoning step by step. What does he mean by “motion”? Why does every change require a cause? And how does observing change in the world lead Aquinas to conclude that there must be an Unmoved Mover upon whom everything else depends?

In this episode, we discuss:

  • What Thomas Aquinas means by “motion”
  • The difference between potentiality and actuality
  • Why nothing can move itself from potential to actual
  • How chains of simultaneous cause and effect differ from causes stretching through time
  • Aquinas’ distinction between primary and secondary causes
  • Why an infinite hierarchical series of causes cannot explain change
  • The meaning of the Unmoved Mover
  • Why Aquinas’ First Way is a philosophical argument for God’s existence, and not yet a complete proof of every Christian belief about God

This episode is part of our series on St Thomas Aquinas’ Five Ways and the classical arguments for the existence of God. Whether you’re interested in philosophy, Catholic theology, apologetics, metaphysics, or the relationship between faith and reason, I hope these episodes help make Aquinas’ thought more accessible and encourage you to explore his arguments for yourself.

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For anyone curious about the foundations, traditions, and everyday implications of the Catholic faith, Crash Course Catholicism offers a thoughtful and accessible entry point. Hosted by theologian Dr Caitlin West, this podcast breaks down complex theological concepts, historical context, and Church teachings into clear, manageable conversations. Each fortnightly episode focuses on a specific topic-from the sacraments and scripture to moral philosophy and liturgical practice-providing listeners with a structured yet engaging overview. Dr West’s approach is both scholarly and welcoming, making centuries of tradition feel relevant and comprehensible. Whether you're a lifelong parishioner seeking a refresher, someone exploring spirituality, or simply a person with questions about the world's largest Christian denomination, this series is designed to inform without overwhelming. Tune in for a calm, considered journey through the pillars of Catholic thought, all delivered in short, easy-to-digest segments perfect for a daily commute or quiet moment of reflection. You can find more from Dr Caitlin West and the podcast at her website.
Author: Language: en-gb Episodes: 50

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