IF YOU WORRY about the polarization of intellectual life, you’re certainly not the first. Consider Zera Ya’icob, the Ethiopian philosopher who defended a form of intellectual freedom in his Hatata (Inquiry) of 1667. Zera Ya’icob was torn between the religious sects that mingled in 17th-century East Africa. He engaged with Muslims, Coptic Christians, Jesuit missionaries, African Jews, and the local Oromo people, finding that they all said the same thing: “My faith is right and those who believe in another faith believe in falsehood, and are the enemies of God.” At once stimulated and bewildered, he wondered, “Who would be the judge for such kind of an argument?” 
It is easy to sympathize with Zera Ya’icob when reading recent scholarship on the origins of modern science, which is riven by two orthodoxies in particular. One orthodoxy is that modern science was invented in early modern Europe. Important contributions came from other times and places, of course, but the decisive move toward modern science happened in Western Europe in the 17th century. The task of the historian of science is to understand how and why. If you disagree with this narrative, you may be accused of relativism, postmodernism, political correctness, or of not doing your job.
The second orthodoxy is that the first orthodoxy is wrong: science is global, not European. It took shape over many centuries, with the help of many cultures. To think otherwise is to buy into a myth about the inevitable rise of the West. The notion of “the West” is itself the product of recent geopolitics. The idea that science is Western is not just wrong, but wrong-headed. It is like a bad cold, or the Cold War. We just need to get over it.
Who would be the judge of such an argument? The two schools not only make different claims but make them in starkly different ways. The first school is old but cohesive. The second is young but diffuse, made up of many stories rather than one story. It is easy to see why. Writing a history of European science is hard enough, with five centuries to cover and many scientific disciplines to master. Writing a history that takes in the rest of the world is a political and methodological minefield. Doing this in a way that appeals to the general reader looks like a fool’s game.
James Poskett, a historian of science and technology, is no fool. His new book, Horizons, is superb. It runs from 1400 to 2000, from the construction of the Samarkand Observatory to the completion of the Human Genome Project. It covers the human sciences as well as the natural sciences, taking in medicine and engineering along the way and covering a great range of people, places, and predicaments. We learn about an Ottoman astronomer captured by pirates in the 16th century; a Tahitian chief charting the Pacific Ocean in the 18th century; a geneticist working to save his life in communist China. Inevitably, there are gaps: Australia, the Holy Roman Empire, economics, most of the earth sciences, experimental science before 1800, Africa after 1800. The book is under 400 pages after all (without footnotes), and so it does not purport to be complete, which would indeed be foolish.
Horizons is global not only in its geographical scope but also in its narrative technique. Poskett uses concrete examples to reveal connections and similarities between parts of the world that are usually studied separately. The Ottoman astronomer Taqi al-Din spent much of his youth bouncing around the Mediterranean Sea, from Cairo to Rome to Istanbul. He bounced around intellectually as well, translating Arabic works into Latin while he was in Rome and introducing European clocks to a new observatory in Istanbul. Some scientists stayed put, including Isaac Newton, a global mathematician who never left England. There he sat, spider-like, at the center of a web of travelers that stretched from Senegal to Peru. Other scientists were more like flies than spiders, trapped in global webs. The physicist Lev Landau made one of his most important theoretical breakthroughs while spending a year in one of Stalin’s prisons. The physician Graman Kwasi was equally remarkable. Born in West Africa around 1690, Kwasi discovered a treatment for malarial fever while working as a slave on a sugar plantation in the Dutch colony of Suriname.
But Horizons is not just a collection of global biographies. These are embedded in a grand narrative about the last 600 years of world history. First comes the expansion of Islamic empires in the vicinity of the Silk Road. Next comes European imperialism: the colonization of the Americas, the transatlantic slave trade, and the exploration of the great expanses of Siberia and the Pacific Ocean. European empires became industrial in the 19th century, fueling nationalistic wars in the process. The 20th century was the age of ideology: fascists, communists, and anticolonialists staked their claims in the first half of the century; and decolonization and the Cold War dominated the second half. The book ends in the present, with the world in the grip of a new Cold War between China and the United States. The war in Ukraine, which broke out while I was writing this review, adds a tragic twist to the narrative.
Poskett links these geopolitical developments to intellectual ones, and much of his book’s originality lies in these linkages. The chapter on 19th-century biology, for example, is not simply a survey of the global reception of Charles Darwin’s theory of evolution by natural selection. It is an argument for the connection between biology, war, and nationalism, a connection captured in the phrase “struggle for existence.” Biology was a battlefield, with naturalists using martial metaphors in their theories and gathering specimens in the course of military expeditions. This was true across the globe: in Napoleonic Egypt, in the newly independent Argentina, in a Japan wracked by civil war, and in modernizing China. The titles of other chapters hint at similar arguments: “Newton’s slaves,” “Industrial experiments,” “Genetic states,” and so on. This is not just a history of science. It is a history of the modern world seen through the lens of science.
At the same time, it is the story of “the scientists who have been written out of history,” in Poskett’s words. Their excision was a product of the imperial history that drove so much of modern science. Overcoming this history means many things. It means writing the East into the history of modern science rather than consigning it to an ancient or medieval past. It means closing the gap between Islamic astronomers such as Taqi al-Din and European ones such as Nicolaus Copernicus. It means seeing that Cold War science was about Japan, Mexico, and Israel, not just about the USA and the USSR. It means realizing that imperial science was often done by the victims of empire, such as the Peruvian Indians whose labor helped to prove Newton’s theory of universal gravitation. These people were “barely distinguishable from beasts,” according to the French astronomer Charles-Marie de la Condamine. Yet the Frenchman relied on the astronomical expertise of these “beasts” in some of the most precise measurements done in the 18th century.
Indigenous knowledge is a major part of the book, but Poskett is no relativist. He does not say that science is just one form of knowledge among many other forms of knowledge. By “science” he means canonical topics like universal gravitation, natural selection, botanical classification, and molecular biology. The point is that the canon itself is global. As a result, Poskett is not afraid to praise the canon. He writes in terms of discoveries, breakthroughs, ingenious instruments, and keen scientific minds. He does not shy away from comparative judgments. The Aztecs were “particularly advanced” among American peoples in precolonial times; Russia “seemed stuck in the past” in the 17th century. This is a celebration of science as well as a critique of empire.
All this makes for a good story. But is it true? Or is it just another myth? There is no simple answer to this question. Horizons has several lines of argument, some more convincing than others. Poskett certainly shows that modern science was made by many people outside Europe who are undervalued in existing histories. He also shows that world history and global exchange are an excellent framework for understanding past science.
But he sometimes goes further. He writes that the Eurocentric story told by past historians is “a myth.” He also charges these historians with “European exceptionalism.” This suggests that there was nothing exceptional about Europe in the history of modern science. A different thesis is that Europe was exceptional, but mainly because of the wealth and power brought about by empire. A third thesis is that science develops when cultures come together and not when they stay apart.
These are all comparative claims. They compare Europe with the rest of the world, empire with other historical phenomena, and cultural exchange with cultural separation. To evaluate these claims, we need to see both sides of the comparison. The problem is that Horizons only shows one side of each comparison.
Take the two chapters on the Enlightenment. These open with the statement that we can “better understand” Enlightenment science by thinking about the rise of European empires. There is ample evidence for this in the ensuing pages, which link Newtonian physics to the slave trade, the colonization of the Americas, and the exploration of the Pacific Ocean. But there is no evidence for the much stronger claim a few pages later: that the rise of European empires “best explains” the science of the Enlightenment. To defend this claim, Poskett would need to review all the other explanations for the growth of 18th-century science, from coffee houses to cameralism. But the other explanations are barely mentioned here.
The same goes for cultural exchange. There are many illuminating examples of cultural exchange in Horizons, often centered on artifacts such as maps, books, and instruments. This creates the impression that science thrives on interactions between diverse cultures. On closer inspection, many of these exchanges hint at long periods of separation. European astronomy and Incan astronomy did meet in 1736, when La Condamine and his team took their measurements in Peru. But for all we know, that was the first and last meeting between these two astronomical cultures. Moreover, the periods of separation may help to explain why the exchange was so fruitful. Cultural exchange works because cultures are different, and they are different partly because they develop separately.
Another one-sided comparison involves 17th-century Europe. Yes, there is a section called “The Scientific Revolution, 1450–1700.” But as far as Europe is concerned, the narrative leaps from 1543, when Copernicus declared that the Earth goes around the sun, to 1687, when Newton explained why it does. The most talked-about decades in the history of European science are passed over in near-total silence. The chapter on Renaissance astronomy has nothing to say about the invention of the telescope or the discovery that planets move in elliptical orbits, two milestones that feature in any ordinary history of Renaissance astronomy. This makes sense if the aim is to valorize non-European scientists. But it makes no sense if the aim is to show that Europe was unexceptional. Arguments against exceptionalism can’t just ignore the alleged exceptions. And arguments for the link between science and empire can’t ignore 17th-century Europe. On the received view, Europe already led the world scientifically in 1700, a century before it led the world in political or economic terms. The received view may be false, but it deserves a better falsification.
On current evidence, it is hard to avoid the conclusion that Europe was exceptional after all. Chapter one of Horizons helps to explain why European natural history was distinctive: it was transformed by the new knowledge generated by the colonization of the Americas. Chapter two is a global survey of astronomy that contains many surprises, but nothing quite as novel as telescopes and elliptical orbits. The material on China does little to disturb the conventional view that Europe raced ahead of China in terms of scientific achievement after 1500, and that China has only just caught up. The chapters on the 19th and 20th centuries cover an amazingly diverse group of scientists who had one thing in common: they all — or nearly all — learned much of their science from institutions that were either in Europe or were modeled on institutions in Europe. Europe is a black hole in Horizons. It is barely visible, but everything seems to gravitate around it.
Why does this matter? Why do we feel the need to show that modern science owes as much to Tokyo and Timbuktu as it does to Paris and London? After all, there is no rush to show that all cultures have made equally important contributions to slavery, for example. This is presumably because we value science but not slavery. We assume that science is a mark of rationality and a source of material progress, a sort of IQ test for world cultures.
Horizons doesn’t exactly support this assumption. It suggests that the main functions of science over the last 600 years have been to wage war, build empires, and rationalize racial prejudice. The book also suggests that any improvements that science has made to our understanding of the natural world are a historical accident. The narrative is driven by the interactions between individuals, nations, and empires. The narrative is not driven by the interactions between theory, experience, and mathematics. In the index there is a large entry on “empire,” but no entry on “empiricism.” Horizons has a lot to say about the politics of science, but little to say about the epistemology of science, and what it says about the former does not flatter science. This is a celebration of science that does not explain why science is worth celebrating.
Horizons shows the immense potential of global histories of science, but it also shows the continued need for other approaches. We need histories of science in Europe, because we need to know what happened inside the black hole. We need epistemic histories of science, because the value of science depends on its ability to understand the natural world. We also need relativist histories of science, because science is not the only way to be rational, and not always the best way. And we need national and regional histories, because cultural separation is as much a part of modern history as cultural exchange.
Let us remember Zera Ya’icob. We need to decolonize history, but we also need to depolarize history. Only then will we get over the Cold War.
Michael Bycroft is an assistant professor in History of Science and Technology at the University of Warwick.
 Zera Ya’icob, “God, Faith, and the Nature of Knowledge,” in African Philosophy: An Anthology, ed. Emmanuel Chukwudi Eze (Oxford: Blackwell, 1998), 457–461, on 457. Quoted in Emmanuel Chukwudi Eze, On Reason: Rationality in a World of Cultural Conflict and Racism (Duke University Press, 2008), 128.