Galileo Galilei
Nature follows mathematical laws, and we discover them by measuring and experimenting rather than by trusting ancient authorities.
Placement
The book of nature is written in the language of mathematics (“The Assayer”, 1623): with telescope observations and experiments on motion he helped to found mathematical-experimental physics.
Key ideas
- Mathematization of nature
- Experiment
Influence
Influenced by 4
Plato
influenced by
Galileo’s Dialogo (1632) alludes to Plato’s doctrine of recollection; Koyré read his mathematical physics as Platonism, a thesis many historians qualify (‘Galileo and Plato’, 1943). Galileo, Dialogo sopra i due massimi sistemi del mondo (1632); A. Koyré, “Galileo and Plato”, Journal of the History of Ideas 4 (1943); SEP “Galileo Galilei”
Evidence: AI draft
Plato › 428–348 BCE
John Philoponus
influenced by
In his early De motu (c. 1590) Galileo cited Philoponus, whose objections to Aristotle’s dynamics of motion in a medium and in the void he partly shared. Galileo, De motu antiquiora (c. 1590); SEP “Philoponus”; R. Sorabji (ed.), Philoponus and the Rejection of Aristotelian Science (1987)
Evidence: AI draft
John Philoponus › c. 490–570
John Buridan
influenced by disputed
Galileo’s early De motu (c. 1590) used an impressed force close to Buridan’s impetus; whether Paris impetus theory led to his mechanics, as Duhem claimed, is disputed. Galileo, De motu antiquiora (c. 1590); P. Duhem, Études sur Léonard de Vinci, vol. III (1913); SEP “John Buridan”; SEP “Galileo Galilei”
Evidence: AI draft
John Buridan › c. 1300–1360
Nicolaus Copernicus
influenced by
Galileo defended Copernicus’ heliocentric system with telescopic evidence (Sidereus nuncius, 1610) and in the Dialogo (1632), which led to his condemnation in 1633. Galileo, Sidereus nuncius (1610); Dialogo sopra i due massimi sistemi del mondo (1632); SEP “Galileo Galilei”; SEP “Nicolaus Copernicus”
Evidence: AI draft
Nicolaus Copernicus › 1473–1543
Influenced 4
Tommaso Campanella
influenced
In his Apologia pro Galilaeo (written 1616, printed 1622) Campanella defended Galileo’s freedom to pursue Copernican astronomy and held it compatible with Scripture. T. Campanella, Apologia pro Galilaeo (written 1616, printed Frankfurt 1622); SEP “Tommaso Campanella”
Evidence: AI draft
Tommaso Campanella › 1568–1639
Thomas Hobbes
influenced
Hobbes visited Galileo in 1636 and, in the dedication of De Corpore (1655), praised him for opening the gate of natural philosophy through the nature of motion. T. Hobbes, De Corpore (1655), Epistle Dedicatory; SEP “Thomas Hobbes”
Evidence: AI draft
Thomas Hobbes › 1588–1679
Pierre Gassendi
influenced
Gassendi corresponded with Galileo and tested his principle of shared motion by dropping stones from a moving ship’s mast (On Motion Impressed by a Moving Mover, 1642). P. Gassendi, De motu impresso a motore translato (1642); SEP “Pierre Gassendi”
Evidence: AI draft
Pierre Gassendi › 1592–1655
Isaac Newton
influenced
Newton credited Galileo with having used the first two laws of motion to find the law of fall and the parabolic path of projectiles (Principia, 1687). I. Newton, Philosophiae naturalis principia mathematica (1687); Galileo, Discorsi e dimostrazioni matematiche intorno a due nuove scienze (1638); SEP “Isaac Newton”
Evidence: AI draft
Isaac Newton › 1643–1727
Criticism
Criticizes 1
Aristotle
criticised
Galileo argued against Aristotle’s physics – that heavier bodies fall faster and the heavens cannot change – in the Dialogue (1632) and Two New Sciences (1638). Galileo, Dialogo sopra i due massimi sistemi (1632), Day 1; Discorsi e dimostrazioni matematiche (1638), Day 1; SEP “Galileo Galilei”
Evidence: AI draft
Aristotle › 384–322 BCE
Works
Copernicus versus Ptolemy – the book that led to the trial.
Position
Galileo showed how nature should be studied: by combining precise experiment with mathematical reasoning. The book of nature, he wrote, is written in the language of mathematics, in triangles, circles and other figures. He separated measurable “primary” qualities such as size, shape and motion from “secondary” ones such as colour and taste, which exist only in the perceiver. His laws of falling bodies and his principle of inertia overturned Aristotelian physics. In his Letter to the Grand Duchess Christina he quoted a churchman, usually identified as Cardinal Baronius: the Bible teaches how to go to heaven, not how the heavens go. His conflict with the Church became the lasting emblem of the struggle between science and authority.
Life & context
Born in Pisa in 1564, Galileo taught mathematics in Pisa and Padua. With a telescope he built in 1609 he discovered the moons of Jupiter, the phases of Venus and mountains on the moon, and became court mathematician in Florence. His defence of Copernicus led to his trial by the Inquisition in 1633; he spent his last years under house arrest near Florence and died in 1642.
Further main works
- The Starry Messenger (1610)
- Letter to the Grand Duchess Christina (1615)
- The Assayer (1623)
- Two New Sciences (1638)
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