What Did the Romans Know? An Inquiry into Science and Worldmaking

In the Upper Midwest, "What do you know?" generates the reply "Not much. You?" From the Romans, historians of science typically get a similar answer: "warmed-over Greek science". Daryn Lehoux offers a better answer and new questions. No mere catalogue of accomplishments, his multifaceted book brilliantly rethinks both the Roman and our own approaches to the cosmos.

Lehoux paints the Roman universe (1st century BC to 2nd century AD) as more coherent and intriguing than the potted version, both more akin to our own and more alien. We resonate with their emphasis on laws of nature, but not with a worldview that intertwines nature, ethics, divination and gods, or uses antipathy to explain that garlic neutralises magnets. He goes on to grapple with the epistemo-logical problems that surface when we juxtapose their world and ours: these puzzles become grist to his philosophical mill. Overall, his book beautifully models a sensitive approach to alien science and a philosophical stance that confronts our tensions with it.

Early on, Lehoux uses Cicero's discussion of divination to document his deep appreciation for the way cosmic order and beauty undergird ethical behaviour in politics and religion (proper action towards the gods). This legal and ethical framework shows why "law of nature" is a concept central to Roman, not Greek, understandings of the Universe. I was almost persuaded. Even without legal language, is not Aristotle's universe law-like? Its causes produce the same effects forever.

When discussing the 2nd century AD, Lehoux showcases Ptolemy and Galen. He is at pains to reckon as Roman science their fundamental (Greek) works on the mathematical sciences and medicine. Admittedly, Galen's trajectory from Pergamon ended in Rome, which also ruled Ptolemy's Alexandria. Yet this taxonomy surely gives the Roman legions too much cultural credit. Centuries before their arrival, Alexandria nourished groundbreaking Greek work in the mathematical and medical sciences.

That said, Lehoux's analyses of this material are highly illuminating. He shows Ptolemy and Galen defending experience against the Sceptics' distrust of sense perception and vision in particular. His treatment of Ptolemy highlights especially the impressive and neglected Harmonics, emphasising its combination of mathematical and experimental work, another allegedly early modern achievement.

The concluding chapters brilliantly contribute to both historiography and philosophy of science. With clarity and wit, Lehoux tackles the Roman fact, justified by experience and considered obvious, that garlic destroys the magnet's attraction of iron. He shows that the pair "garlic-magnet" belongs to a "sympathy-antipathy" trope that weakens in the 13th century, yet lingers into the 17th, when appeals to experience still justify it - along with the denials of those effects and the emergence of another explanatory framework. Experience thus includes a theoretical component: what we classify as obvious counts as justified by experience. Note the crucial importance of such classifications in shaping a world.

Lehoux's concluding chapters confront squarely the conundrum of every thoughtful historian of pre-modern science. After defending an alien worldview as coherently true for its adherents, how does one evaluate its claims, some of which seem absurd in the world we inhabit? Does the methodological relativism of historians of early science commit them to philosophical relativism today? Not for Lehoux, who defends a realist epistemology with a pragmatic theory of truth. The last chapter ends with his original question, "What did the Romans know?" His italics are now the time-sensitive font of our newly acquired wisdom. Between the coherent past world that the Romans made and the presumed timelessness of our scientific world, Lehoux leaves us not with an unbridgeable chasm but with his pragmatic realism, born at the confluence of ancient science, historical epistemology and the philosophy of science. First rate.