History of Philosophy Without Any Gaps

Episode 482: Indivisible, Under God: the Revival of Atomism
Host: Peter Adamson
Date: December 14, 2025

Episode Overview

In this episode, Peter Adamson examines the 17th-century revival of atomism as an alternative to the declining Aristotelian worldview. He focuses on the competing atomistic theories of Sebastian Basso and Pierre Gassendi, contrasting their approaches both with each other and with Aristotelian and Cartesian theories of matter. Adamson explores how these atomistic philosophies interacted with religious concerns, including Protestant and Catholic views on the role of God in the natural world.

Key Discussion Points and Insights

1. From Aristotle’s Elements to Early Modern Atomism

• Adamson begins by playfully recalling the puzzlement of a child when a puddle evaporates, using it as an entryway to discuss Aristotle’s theory of the four elements (earth, water, air, fire) and their transformations through “substantial forms” and “prime matter.”
  • "The Aristotelian elemental theory assumes that earth, water, air, and fire have their qualitative features hot and cold, wet and dry because of their substantial forms." (02:10)
• The 17th-century scientific revolution brought skepticism towards these assumptions, most notably with Descartes but also with less well-known figures like Sebastian Basso.

2. Sebastian Basso’s Atomism

• Sebastian Basso, in his Natural Philosophy Against Aristotle (1621), offers a "relentless attack on Aristotelian science" (05:00), proposing a philosophy inspired by ancient atomism (Democritus, Plato’s Timaeus).
• Key Features:
  • Nature composed of "microscopically small atoms."
  • Elements made up of particles with different geometric properties determining element behavior, e.g., "fire atoms have sharp angles, which is why fire destroys things so readily." (06:20)
  • Evaporation explained through a mechanistic story: "When the sun shines on a puddle, the fiery particles that make up the sunlight enter into the water...the vapor that rises from the puddle consists of the resulting corpuscles, each droplet of vapor being a tiny little spark of fire encased in a watery sheath." (07:15)
• Basso remains close to the Aristotelian picture in some respects:
  • Maintains the four elements, rejects the existence of void, and posits a fifth "aether" as a medium that fills space.
  • Movement of atoms attributed directly to God: "It's God who is moving the ether, indeed moving it constantly." (12:25)

3. Pierre Gassendi’s Epicurean Revival

• Gassendi revives Epicurean atomism (unlike Basso, who is more Platonic).
• Key Differences:
  • Strong endorsement of the physical reality of the void: "His most important reason for this belief was taken straight from Epicurus. If there were no void, then space would be completely full and motion would be impossible." (11:20)
  • Initial motion of atoms given by God at creation; atoms retain this motion forever.
• The universe is infinite, not geocentric:
  • Gassendi subtly undermines geocentrism, cautiously leaving room for Copernicanism. He uses examples like tossing a stone from a moving ship and observing that it lands at the ship’s base: "the object will fall right to the base of the mast." (17:55)
• Natural phenomena such as evaporation, perception, gravity, and magnetism all explained by atomic motion and structure.

Notable Quote:

"Gassendi compares the production of our complex visible world out of its invisible atomic components to the way letters can come together to form words and sentences. He might have extended the metaphor to say that God is therefore like an author writing the book that is the Universe." (14:55)

• Gassendi makes distinctions between atomic (micro) and everyday (macro) worlds:
  • Atoms always move, macroscopic bodies can rest or slow down.
  • Gaps in explanation are bridged by hypothesizing "textures" and "seeds" at intermediate scales.

4. Religion and Atomism

• Both Basso and Gassendi rely on divine causality to explain the movement and interaction of atoms—Basso through constant divine intervention, Gassendi through initial divine motion followed by secondary causation.
• Atomism’s religious integration:
  • Atomism can support religious doctrines by making the world’s structure the result of divine providence, and atoms as God's mutable "letters."
  • Atomism appealed to Protestants by undermining the Catholic doctrine of the Eucharist’s transformation:

    "If sensible properties are just the result of atomic structure, then it makes no sense to suppose that the sensible features of bread and wine seem still to belong to substances that are no longer bread and wine..." (28:20)

  • Catholic atomists like Gassendi used atomism to show that God could fashion the world in any way, unconstrained by Aristotelian substantial forms.

Memorable Moments and Quotes

• Opening analogy:

  "One thing you need to learn as a baby is that physical objects don't just vanish into thin air. And one thing you need to learn when you get older is that sometimes they do." (00:15)

• On atomism’s religious appeal:

  "Atomism might seem dangerous from a religious point of view because it could so easily lead to materialism, but in fact, atomism seems to have appealed to many thinkers around this time precisely because it fits so well with their religious convictions." (27:26)

• Adamson’s playful personal aside:

  "In my kindergarten there was one Adam son, actually two, because my brother was there also. And our teacher would have agreed with Gassendi that we were restless, vibrating masses of particles." (22:35)

• Closing teaser:

  "We're going to tackle Blaise Pascal and Antoine Arnaud...before we get to Pascal's wager...we need to introduce the man himself. So join me next time for a true trailblazer. Blaise Pascal here on the history of philosophy, without any gaps." (31:50)

Important Timestamps

• 00:15 — Opening thought experiment: the vanishing puddle and Aristotelian explanations
• 05:00 — Sebastian Basso’s critique of Aristotle and proposal of atomism
• 07:15 — Basso's detailed atomistic account of evaporation
• 11:20 — Gassendi’s Epicurean atomism and the necessity of the void
• 14:55 — The analogy of atoms as letters and God as the universe’s author
• 17:55 — Gassendi’s experiments and support for non-geocentric cosmology
• 22:35 — Micro/macro distinction, metaphors, and Adamson’s anecdote
• 28:20 — Atomism, the Eucharist, and Protestant adoption
• 31:50 — Transition to upcoming episodes on Pascal and Arnaud

Structure and Flow

Adamson guides listeners from Aristotle’s dominance, through the atomistic alternatives of the early 17th century, to the intertwining of science and religion in atomist thought. With clear comparisons and engaging metaphors, he conveys the intellectual landscape of the time, highlighting how atomism became a tool for both scientific explanation and religious expression.

For Listeners

This episode offers:

• A deep, engaging exploration of how early modern atomists challenged old certainties
• Comparison of major figures and theoretical nuances (void, aether, initial motion, divine causality)
• Context on how philosophy and religion intersected in early modern science

Even without listening, this summary should provide a rich understanding of the era’s debates about the fundamental nature of matter and the ever-present influence of theological concerns.