Robert Boyle

By Laura Whitfield

He was the fourteenth child of the Earl of Cork, one of the richest men in Ireland — and he spent the fortune on air pumps. Robert Boyle, born in 1627 at Lismore Castle, could have lived as an aristocratic dilettante; instead he became the man who taught science to distrust everything, including itself. After a Grand Tour and years of private study, he settled at Oxford in the 1650s among the group that would become the Royal Society, and with his assistant Robert Hooke built an improved air pump — the great engine of the new experimental philosophy.

With it, Boyle did the experiments that made his name: exhausting air from a receiver and watching a feather and a coin fall together, a bell go silent, a candle die, an animal gasp. From careful measurements of trapped air compressed by mercury came Boyle's law — pressure times volume is constant — the first great quantitative law of gases, published in 1662. But the law was almost incidental. What mattered was the book it rode in on: The Sceptical Chymist (1661), which attacked the reigning theories of matter — Aristotle's four elements, the alchemists' salt-sulfur-mercury — and proposed instead that matter consists of corpuscles, with elements defined operationally: whatever cannot be broken down further by chemical means. Chemistry began to separate from alchemy at that sentence.

Boyle was also the great theorist of method. In an age of secretive virtuosi, he insisted on publishing full experimental details so others could replicate results — the birth of reproducibility as a norm — and he waged a famous philosophical war with Thomas Hobbes over the air pump itself, defending the proposition that a machine, properly witnessed, could establish a matter of fact. Steven Shapin and Simon Schaffer would call it the founding quarrel of modern science.

Deeply devout, he endowed the Boyle Lectures to reconcile science and religion, never married, lived with his sister in London, and died in 1691 — refusing, characteristically, the presidency of the Royal Society. He had turned chemistry from a mystery into a discipline, and skepticism from a pose into a procedure.

Impact on civilization

Boyle founded modern chemistry by replacing the elements of Aristotle and the alchemists with an operational definition — an element is what analysis cannot decompose — and by insisting that theories answer to experiment. Boyle's law gave the first quantitative regularity of gases, the seed of thermodynamics and kinetic theory. His doctrine of full, replicable experimental reporting created the modern scientific paper and the norm of reproducibility; his defense of the air pump against Hobbes established that instruments and witnessed experiments, not metaphysical argument, settle matters of fact. Chemistry, and the experimental method itself, date their modernity from him.