God's Philosophers by James Hannam – review

In canto XVII of Inferno, Dante anticipated the principle of Galilean invariance 300 years before Galileo. Even earlier, Islamic steelmakers in Damascus unwittingly exploited nanotechnology in the manufacture of sabres that became the envy of the world. So the middle ages weren't so medieval.

Almost the only annoying thing about James Hannam's admirable book is his opening insistence on a conspiracy of "popular opinion, journalistic cliche and misinformed historians" to denigrate the middle ages, and he cites the compass, Columbus and the 1455 printed Bible of Gutenberg as advances of the middle ages. In this conspiracy, whenever someone discovered evidence of reason or progress in the 14th or 15th centuries, he writes "it could easily be labelled 'early-Renaissance' so as to preserve the negative connotations of the adjective 'medieval'." The OED gives no dates for the medieval period, but it tells me that the Renaissance began in Italy in the 14th century.

Hannam's thesis is that, by thinking critically, and by challenging classical authority, the natural philosophers of the medieval world prepared the way for modern science. He sees – Hannam is not alone in this – the history of medieval thought as a long and sometimes prickly conversation about Aristotle. The Church had its own problems with Aristotle, but concluded that he was broadly right, except when he was wrong, and philosophers should respect Aristotle except when his views clashed with Holy Writ.

The great names of the cathedrals and the abbeys and universities flit across the pages, beginning with Anselm of Canterbury, Adelard of Bath and the Heloise-loving Peter Abelard (I am grateful to learn that Abelard later claimed that during his vengeful castration by Heloise's family "he hardly felt a thing".) Roger Bacon, Bernard of Clairvaux and Thomas Bradwardine of Merton College encourage a fleeting suspicion that history happened in alphabetical order.

Names that are new to me put in an all-too-fleeting appearance: Buridan of Paris and his student Nicole Oresme examine some Aristotelean physics, including the physics of movement, a recurring theme and come to the conclusion that although Aristotle was surely wrong about the propulsion of projectiles, he was right about a stationary Earth in a geocentric universe.

By the close of the book, as Galileo begins to clear up the confusions one by one, the reader has no problem with the argument that modern science grew from a substrate prepared by generations of thinking churchmen and scholars, and that the church actively encouraged natural philosophy that wasn't heretical. But is that the same as laying the foundations for the experiment and observation pioneered by Galileo and his successors? And is anticipation the same as precedence?

Dante Alighieri did indeed anticipate Galileo, but Dante was a poet anxious to move his characters through the precise topography of his imagined Hell: his is a solution to a poetic problem, not a principle to be framed as a mathematical equation. And the Saracen blade-makers were resourceful experimenters who got lucky with the import of wootz from India. But did they exploit nanotubes as a considered technological innovation? I only ask.