How a medieval Andalusian polymath challenged Aristotle and paved the way for Galileo

Ideas & Philosophy · Published 29 September 2026 Swipe more like this →

In short: Avempace was an Arab polymath whose radical ideas on physics and the soul defied the Aristotelian consensus of his time. By proposing that motion in a vacuum need not be instantaneous, he anticipated modern dynamics, influencing thinkers from Maimonides to Galileo Galilei while navigating the volatile politics of Al-Andalus.

Born around 1085 in Zaragoza, Avempace—known in Arabic as Ibn Bajja—was a prolific intellectual whose work spanned botany, medicine, music, and philosophy. Despite his early death in 1138 in Fes, his influence was profound. He served as a vizier under Almoravid rulers, though his career was marked by political instability, including two imprisonments and rumors of poisoning by rivals. His intellectual legacy survived largely through the preservation of his theories by later scholars like Moses Maimonides and Averroes.

Avempace’s most striking contribution to physics was his critique of Aristotle’s theory of motion. While Aristotle argued that velocity was inversely proportional to the density of the medium, Avempace proposed that resistance acts as a subtractive force. He argued that if motion were purely a function of medium density, movement in a vacuum would be instantaneous—a conclusion he rejected. This insight, preserved in the text known as 'Text 71,' suggested that velocity is the difference between motive power and resistance. Centuries later, Galileo Galilei would adopt a similar formula, marking a significant departure from ancient physics.

In philosophy, Avempace is best known for his unfinished treatise, 'Governance of the Solitary.' He envisioned a 'perfect city' free from false beliefs, where true science reigns. However, recognizing that such cities are rare, he argued that the 'perfect man' must often live in isolation to protect his soul from the 'weeds' of imperfect society. His focus on the 'conjunction' of the human intellect with the active intellect became a cornerstone of his thought, emphasizing that the ultimate human objective is the contemplation of truth.

Beyond his theoretical work, Avempace was a keen observer of the natural world. He wrote extensively on botany, classifying plants by their reproductive nature, and made notable astronomical observations, including the transit of planets and a unique theory regarding the Milky Way as a phenomenon of both sublunar and celestial spheres. Though much of his writing remains fragmented, his 'sharp reasoning' and willingness to challenge established dogma cemented his status as a pivotal figure in the transition of medieval thought.

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