3.9 Scientific, Philosophical, and Political Developments

The Scientific Revolution reshapes thought

Building on the earlier Copernican break from geocentrism, thinkers like Kepler, Galileo, and Newton used observation, mathematics, and experimentation to describe a universe governed by natural laws. Newton's Principia Mathematica (1687) synthesized physics and astronomy with universal gravitation, proving reason could uncover nature's hidden order — inspiring confidence that human reason could improve society too.

New methods of inquiry

Francis Bacon promoted the empirical/inductive method (observation and experiment leading to general conclusions), while René Descartes championed deductive reasoning and rational skepticism ('Cogito, ergo sum'). Together these methods formed the foundation of the modern scientific method, encouraging Europeans to question tradition, authority, and religious dogma in favor of evidence-based reasoning.

Political theory follows suit

Applying reason to politics, Thomas Hobbes argued in *Leviathan* that humans need an absolute sovereign to escape a brutal state of nature. John Locke, in contrast, argued in *Two Treatises of Government* that people have natural rights to life, liberty, and property, and government exists by a social contract that can be overthrown if it fails to protect these rights — laying groundwork for later liberal and constitutional thought.

Key terms

Principia Mathematica

Isaac Newton's 1687 work establishing universal gravitation and laws of motion, synthesizing the Scientific Revolution.

Empiricism (Francis Bacon)

Method of gaining knowledge through observation and experiment, forming general conclusions inductively.

Deductive reasoning (René Descartes)

Method starting from self-evident truths and using logic to reach conclusions; famous for 'Cogito, ergo sum.'

Thomas Hobbes / Leviathan

Argued humans need an absolute sovereign to escape the violent, chaotic 'state of nature.'

John Locke / social contract

Claimed government must protect natural rights (life, liberty, property); people may overthrow it if it fails.

Try an AP-style question

Galileo's telescope observations supported…

1. the heliocentric model
2. the geocentric model
3. astrology
4. a flat Earth