Poincaré asks how much of science is discovered in nature and how much depends on the conceptual language used to organize experience. His discussions of geometry, measurement, motion, probability, optics, and electrodynamics reject both naive certainty and arbitrary relativism.
The book rewards slow reading because its central question remains active: evidence constrains theories, but scientists still choose definitions, models, and mathematical structures. Those choices are judged by consistency, usefulness, and contact with observation.
About this free edition
This catalog record links to Project Gutenberg’s public-domain edition. Historical science books are valuable primary sources, but older claims should be compared with current evidence before being treated as modern scientific guidance.
