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General Philosophy · Lecture 5 of 33 · 5:50

2.1 Recap of General Philosophy Lecture 1

2.1 Recap of General Philosophy Lecture 1 on YouTube

Study guide

What this lecture covers

This short lecture recaps the previous two and a half lectures before moving on to new material. It restates why the 17th and 18th centuries are pivotal for philosophy and why the problems from that period remain relevant today.

Millican summarizes how the medieval worldview, dominated by Aristotle and the Bible, explained physical behavior on the model of desire or striving, and how this broke down under pressure from Galileo's telescopic observations and from the emptiness of 'striving' as an explanation. He then recaps Descartes's mechanical alternative, in which matter's essence is extension and all motion takes the form of vortices, used to explain why the Moon and planets orbit rather than travel in straight lines.

Key ideas

  • Aristotle's two-tier physics: earthly bodies strive toward the center of the universe, while heavenly bodies made of ether strive to move in circles.
  • Empty explanations: appealing to desires or strivings explains nothing, since it can be used to justify any observed behavior after the fact.
  • Galileo's telescope: observations of lunar craters, Jupiter's moons, and the phases of Venus contradicted the Aristotelian theory of a perfect, unchanging heaven.
  • Mechanism: the 17th-century replacement theory, in which physical things act through contact, pressure and impact rather than desire.
  • The orbit problem: inertia implies bodies move in straight lines unless a force acts on them, leaving orbital motion unexplained.
  • Descartes's vortices: because matter is pure extension, empty space is impossible, so all motion takes the form of circulating vortices that carry planets and moons around.

Before you watch

  • This lecture assumes you have watched lectures 1.2, 1.3 and 1.4, which it summarizes.

Check your understanding

  1. Why is 'things strive to do X' considered an empty explanation?
  2. What did Galileo's telescope reveal that contradicted Aristotelian astronomy?
  3. How does Descartes use the idea that matter is extension to explain planetary orbits?

Vocabulary

recap (noun)
A short summary of what was already covered.
This lecture is a recap of the previous few lectures.
pivotal (adjective)
Extremely important because everything else depends on it.
The 17th and 18th centuries were pivotal for philosophy.
worldview (noun)
A person's or a period's overall way of understanding the world.
The medieval worldview was dominated by Aristotle and the Bible.
desire (as explanation) (noun)
The idea, used in older theories, that objects act because they want or aim for something.
Explaining motion through desire was later seen as empty.
striving (noun)
The act of aiming or reaching toward a goal.
Aristotle described falling objects as striving toward the center.
telescopic (adjective)
Made possible by, or seen through, a telescope.
Telescopic observations contradicted old astronomy.
crater (noun)
A bowl-shaped hollow on the surface of a planet or moon.
Galileo saw craters on the Moon's surface.
mechanism (noun)
The theory that natural events happen through physical contact and force, not purpose.
Mechanism replaced explanations based on desire.
orbital motion (noun)
The circular or curved movement of one body around another.
Inertia alone leaves orbital motion unexplained.
circulate (verb)
To move continuously in a circle or loop.
Matter was thought to circulate in vortices around the Sun.
two-tier (adjective)
Having two distinct levels or layers.
Aristotle's two-tier physics separated Earth from the heavens.
restate (verb)
To say something again, often more clearly or briefly.
The lecture restates why the 17th century matters.
summarize (verb)
To give a brief statement of the main points.
Millican summarizes the previous lectures' key claims.
justify (after the fact) (verb)
To defend or explain something only after it has already happened.
Striving could justify any observed behavior after the fact.
replacement (theory) (noun)
A new theory that takes the place of an older, rejected one.
Mechanism was the 17th-century replacement theory.
relevant (today) (adjective)
Still important or applicable in the present.
The problems from this period remain relevant today.
pressure (from evidence) (noun)
A strong influence pushing a theory toward change or collapse.
New evidence put pressure on Aristotelian physics.
short lecture (phrase)
A brief talk covering less material than usual.
This short lecture recaps the earlier material.
carry around (phrasal verb)
To move something along in a circular or repeated path.
Vortices carry planets around the Sun.
assume (a prior lecture) (verb)
To take for granted that something is already known.
This lecture assumes you've watched the earlier ones.

Chapters

From the YouTube description

A series of lectures delivered by Peter Millican to first-year philosophy students at the University of Oxford. The lectures comprise the 8-week General Philosophy course and were delivered in late 2009.

Slides for all his lectures can be found here:
http://podcasts.ox.ac.uk/people/peter-millican

Learn more about Oxford:
http://www.ox.ac.uk

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