Great IdeasNature and science
Cause and chance
Why things happen: causes, purposes and luck.
The question
Why do things happen? Do events have causes and purposes, or does chance play a part?
How the books answer
Oldest first. Each stop is our own short summary of what the author argued; follow the link to the rung for the whole lesson.
late 5th and 4th centuries BC
Hippocrates and his school, The Oath, On Ancient Medicine, On Airs, Waters, and Places, Aphorisms, The Sacred Disease, and other works
The Hippocratic doctors look for natural causes of disease: winds, water, seasons, diet. They reject explanations by the anger of gods. Finding the cause, they believed, is the first step toward a cure.
“Men regard its nature and cause as divine from ignorance and wonder, because it is not at all like to other diseases.”
c. 350–322 BC
Aristotle, Physics
Aristotle names four kinds of cause: what a thing is made of, its form, what started it, and what it is for. A statue's bronze, its shape, its sculptor and its purpose all help explain it. He thought nature too acts for ends, as an acorn grows toward an oak.
“Again (4) in the sense of end or 'that for the sake of which' a thing is done, e.g. health is the cause of walking about.”
c. 55 BC
Lucretius, On the Nature of Things (in the set: The Way Things Are)
Lucretius explains everything by atoms moving and colliding, with no purposes and no gods steering. To leave room for free will, he says atoms sometimes swerve slightly, by chance. Nature, for him, is cause and chance, not plan.
1265–1274 (unfinished)
Thomas Aquinas, Summa Theologica, First Part
Aquinas argues that a chain of causes can't go back forever without a first cause, and that things in nature act for ends as if directed. He calls the first cause and director God. He also holds that God works through natural causes, which science can study.
“Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.”
1677 (published after his death)
Baruch Spinoza, Ethics, Demonstrated in Geometrical Order
Spinoza holds that everything follows necessarily from the nature of God, or Nature, as a theorem follows from geometry. There is no chance and no purpose in the usual sense. Understanding the causes of things, he thinks, brings peace.
1748
David Hume, An Enquiry Concerning Human Understanding
Hume asks what we really see when one billiard ball strikes another. We see one motion followed by another, but never the power that links them. Our idea of cause, he argues, comes from habit after seeing the same thing happen again and again.
“May not the first ball return in a straight line, or leap off from the second in any line or direction?”
Go to the rung: Hume: An Enquiry Concerning Human Understanding
1759
Voltaire, Candide
Voltaire mocks Dr. Pangloss, who insists that everything happens for the best, no matter how terrible. Pangloss finds a purpose for everything, even noses made to hold spectacles. Voltaire's target was a kind of easy optimism about causes and purposes.
“Observe, that the nose has been formed to bear spectacles—thus we have spectacles."”
1865–1869
Leo Tolstoy, War and Peace
Tolstoy asks what caused Napoleon's invasion of Russia. Not Napoleon alone, he answers, but millions of causes in millions of people. Historians who name one cause are, in his view, fooling themselves.
1958
Werner Heisenberg, Physics and Philosophy
Heisenberg explains that in quantum physics, single events like an atom's decay can be predicted only as probabilities. Chance seems built into nature at the smallest scale. Physicists still debate what that means.
For young readers
A cause is what makes something happen. If you drop a glass, the glass breaks. The drop is the cause; the broken glass is the effect.
Aristotle asked four 'why' questions about a thing: What is it made of? What shape is it? Who or what made it? What is it for? Try them on your toothbrush!
Talk about it
- Ask Aristotle's four questions about a chair. What are the answers?
- Is anything really an accident, or does everything have a cause?
- Hume says we never see the cause itself, only one thing after another. Is he right?
- Pangloss thought everything happens for the best. What did Voltaire think of that?
- What caused something good that happened to you this week?
Where else on the site
- Reasoning about Causes
- False Cause
- Causes, Effects and Change Over Time
- Observational Studies and Experiments
- Wave Functions and Probability
Every rung tagged with this idea:
These pages are our own short synthesis, written for families. They were inspired by Mortimer J. Adler's Syntopicon, the index of great ideas in volumes 1 and 2 of Great Books of the Western World, but the questions, summaries and groupings are ours, not the Syntopicon's. Short excerpts come from public-domain translations, credited where they appear.