Part of the way the prestige of science has been established in our own time is through the rhetoric of favorable contrasts. In previous articles, we’ve seen one instance of this contrast in the tripartite division of European history: rational inquiry flourished in the ancient world, withered in the medieval times, and was revived again in the time of the Renaissance and the Enlightenment. The names themselves are suggestive: a Renaissance, or “rebirth,” presupposes a prior death; an “Enlightenment” presupposes a prior darkness. The death and darkness referred to in these metaphors are the medieval times, in which, we are told, the light of reason had been nearly extinguished. The implicit, often explicit, villain in this history is theology. Since we all know that the medieval times were very religious, and that there is a lot of tension in discussions about science and religion in our time, it stands to reason that there was back then too, and that’s why science languished.
Another form of contrast is by way of distinguishing “the West and the rest,” where “the West” stands for reason, liberty, and affluence, and “the rest” for ignorance, tyranny, and poverty. What is it about “the West,” we are invited to ask ourselves, which has made it so distinctly successful? By contrast, what is it about “the rest” that accounts for their failure? The nearest neighbor and most frequently employed prop in this exercise in self-congratulation is “the house of Islam.” Nobel laureate Steven Weinberg, for instance, draws this unfavorable comparison in his article, “A Deadly Certitude,” for the Times Literary Supplement, in which he informs us,
Alas, Islam turned against science in the twelfth century. The most influential figure was the philosopher Abu Hamid al-Ghazali, who argued in The Incoherence of the Philosophers against the very idea of laws of nature, on the ground that any such laws would put God’s hands in chains. According to al-Ghazali, a piece of cotton placed in a flame does not darken and smoulder because of the heat, but because God wants it to darken and smoulder. After al-Ghazali, there was no more science worth mentioning in Islamic countries.
In a lecture entitled “The Islamic Golden Age: Naming Rights,” physicist and science popularizer Neil deGrasse Tyson repeated this story. After extolling the accomplishments of Islamic science in the period c. 800–1100 CE, he identifies the decline of Islamic science with the pernicious influence of al-Ghazali, saying,
In the twelfth century, you get the influence of this scholar, al-Ghazali. Out of his work you get the philosophy that mathematics is the work of the Devil, and nothing good can come of that philosophy. … that, combined with other … philosophical codifications of what Islam was and would become, the entire philosophical foundations of that enterprise collapsed and it has not recovered since.
It’s another story about how science has to struggle against the pernicious influence of theology in order to get anything done, and Tyson, like Weinberg, is not shy about drawing connections to the present. Both of these comments are situated explicitly within the context of “the war on terror,” which they see in light of the conflict narrative (i.e., between science and religion) we discussed in an earlier article. I’ve suggested that the view of these physicists should not be taken at face value. But are there weightier reasons to doubt this story than a reflexive suspicion of self-congratulatory narratives? In what follows, we’ll follow (loosely) the argument of philosopher of science Arun Bala in his paper, “Did Medieval Islamic Theology Subvert Science?”
Al-Ghazali was, undoubtedly, one of the most influential intellectuals of medieval Islam. At the height of a prestigious career as a scholar in Baghdad, the seat of the Abbasid Empire and one of the great cities of the world in its time, al-Ghazali came to feel that service to God and the state were incompatible. He abandoned the life of a scholar to follow the mystical path of Sufi Islam, but he remained involved in the life of the mind. In The Incoherence of the Philosophers, al-Ghazali attacked the Greek philosophers and their continuing influence in Islamic intellectual life. He had come to see it as something foreign and incompatible with the genuine spirit of Islam. Like William of Ockham, two centuries later, he wanted to get back to a more original form of the faith. And, like Ockham, he put a great deal of emphasis on God’s omnipotence.
One part of Greek philosophy that he particularly disliked was the Aristotelian notion of causality. Aristotle held what we would probably call a common sense view of causality. If we see a billiards ball strike another, and the second ball fall into a pocket, we naturally think that the impact of the first on the second is what caused it to move. The assumption is that causal power is latent in objects themselves, a view known in medieval theology as naturalism. It seems like a perfectly sensible assumption, and it doesn’t often get attacked, although sometimes it does. Al-Ghazali was one of the philosophers who did attack it. He pointed out that you don’t actually see the causal relation. What you see is a correlation. Billiards balls striking each other correlates with their moving around. So he’s not saying that we don’t observe what we observe, he’s saying that we don’t observe causality. After all, what is causality? According to al-Ghazali, it’s an unexamined assumption; it can’t be sustained through reason alone, it’s just something people take for granted. Further, it seems to impinge on God’s omnipotence. If objects have causal power in themselves, then the relations between causal relations would seem to be necessary relations. If they’re necessary relations, God can’t interfere with them. How, then, can God act in the world? There seemed to be a move toward expelling God from the cosmos, and al-Ghazali doesn’t like that.
This might sound familiar. One argument that is often made against miracles is that they would violate the laws of nature. God would not create a law, it is argued, only to break it on a special occasion, only to reinstate it afterward. It seems arbitrary and messy. The causal potency of natural objects seems to leave no room for the causal potency of God. If that’s true, God’s existence is irrelevant for science, as in Deism or Pantheism, or hostile to it, as in faiths that affirm the miraculous. There’s a uniformity principle that miracles seem to violate, and that’s a cause of concern for scientific naturalists.
What to do? To counter naturalism and preserve God’s omnipotence, al-Ghazali argued that the causal potency that we think we detect in the world around us is really the causal potency of God. Put differently, there is no causal potency apart from that of God; God does everything everywhere and at all times. This view is called occasionalism because it sees phenomena as occasions for God’s activity. Like scientific naturalism, it resolves the conflict between competing causal potencies by eliminating one of the contending parties—it just reverses the order by eliminating natural potency instead of God’s. Occasionalism also resolves the issue with miracles by simply denying the uniformity principle. We think that uniform causes produce uniform effects, but since there really is no cause except that of God, according to occasionalism, and since God is a sentient agent who makes choices, similar effects do not necessarily follow from what, from a naturalistic point of view, would seem to be similar causes.
It’s sometimes been suggested that this creates a totally unpredictable, topsy-turvy universe that makes science impossible. You have to have complete uniformity, or you can’t have science. I’m not so sure about that. It’s true that you have to have a lot of uniformity: if you can’t predict similar outcomes form similar circumstances, it’s hard to see how you could say much of anything about the world except that it’s unpredictable. But it doesn’t automatically follow that a different effect in, let’s say, one out of ten billion similar situations is the ruin of science. It would mean that causal relations that science leads us to suppose will pertain, will, in a very small number of instances, not in fact pertain. This is actually already the case in a lot of science. To say that the natural world occasionally upsets our expectations is just to say that we don’t completely understand it, and who doubts that? The scientist may insist that although we don’t understand the phenomena in question now, eventually we will, and when we do we will see that the relation is, in fact, uniform. That might be right, but until we arrive at a complete causal explanation of every phenomena, it’s an expectation about what science will do, not a settled fact about what it has done. Further, it’s always possible that we’ll think we have an explanation when in fact we don’t. The history of science is replete with good, successful explanations that later turned out to be wrong. But they weren’t known to be wrong at the time, they were only seen to be wrong once another theory came around and replaced it—which then, often enough, acquired the same protective aura of a completed explanation.
The real issue for science is not the mere existence of exceptions, but their prevalence. An exception that pertains in one out of ten billion cases is not that big of a concern. We drive on freeways all the time, where the rate of a violent death is much higher than one in ten billion. But as the chances increase, the legitimacy of the worry does as well. If the theory of, let’s say, radioactive decay, proved unreliable one out of every three times, that would be a real problem. We probably wouldn’t want to build nuclear reactors that depend on the uniformity of radioactive decay on that basis. In a similar way, a world picture in which miracles occur right and left every day probably is incompatible with science. But that’s not obviously the case with a world picture in which miracles are very, very rare. At any rate, many great and very productive scientists have believed that miracles can and do occur, so just empirically the naturalistic complaint about miracles being incompatible with science doesn’t seem to be borne out. What it’s incompatible with is scientism—the claim not just of validity, but of exclusive validity, for the sciences.
A further evidence that this view is not necessarily destructive of science is that something quite like it was affirmed by David Hume, the very symbol of Enlightenment, rationalist skepticism. Hume, of course, did not believe in God, and therefore not in God as the only true cause, but he did criticize the entire idea of causality on similar grounds as al-Ghazali had. It is only custom, not observation, and not reason, Hume says, which causes us to believe that fire heats us, or that water refreshes us. So, for Hume, causality is in us, not in the world, where for al-Ghazali it is in God rather than in the world.
Al-Ghazali’s attacks on Greek philosophy could be seen as a rejection of rationality more generally, or it could be seen as clearing the way for a different kind of rationality. As we’ve seen, in previous articles, the Greeks had some very particular ideas about rationality. They tended to equate it with geometry, and to think that geometric methods were the most suitable for any kind of investigation, where in our time rationality is more often identified with physics and its methods. The tremendous difference between these methods means that you can’t really get to physical methods as long as people are convinced that geometric methods are the best. As we’ve seen, in Europe it was the nominalist attack on the existence of real universals, and, by extension, on the geometric methods associated with their investigation, which cleared the ground for the emergence of new kinds of inquiry, including those that eventually became associated with physics. It is not inconceivable that things might have turned out that way in the Islamic world as well, but because they went another direction, it can look worse than it really was.
So, what caused the decline of Islamic science? Well, recall that al-Ghazali was at one time a scholar in the imperial city of Baghdad. The Abbasid Caliphs wanted their empire to excel all that had come before it—in size, power, wealth, and also in learning. They built a "House of Wisdom" in Baghdad as a kind of second great library, and they used it to fund inquiries into natural philosophy, among other subjects. But learning in the ancient world could be a precarious thing, and in the thirteenth century the Abbasid empire came under attack. The Mongols invaded from the north, burned Baghdad to the ground in 1258, and shattered the Abbasid empire. On the Iberian Peninsula, the Islamic conquest had never quite been complete. In the eighth century, a Muslim army had smashed the Visigoths and driven the remnants of their warrior aristocracy into the mountains of the extreme north. Over the generations, they gradually began the "reconquest" ("reconquista") of the peninsula, and by the thirteenth century they were making major gains. Although far removed from the Middle Eastern heart of the Islamic lands, some of the wealthiest cities, and most learned scholars, of Islam were in Spain. The collapse of Islamic Spain proved a serious blow to the Islamic world as a whole. The Crusader invasions of Palestine should also be mentioned, although in truth they were more of a nuisance than a serious threat to the Islamic Empire.
After the discovery of the New World, Europe began to really take off in terms of its wealth and power. Huge treasure fleets carried the silver and gold of the Americas back to Europe, and soon colonists began to send back timber, furs, metals, and other raw materials. Thousands of plantations were set up for the production of cash crops, bringing with it the cruel enslavement of millions of Africans and Native Americans. European fleets began to enter the Pacific and Indian Oceans as well, and to take over their commerce. All of this came at the expense of the Chinese, Hindu, and Muslim peoples, to say nothing of Africans and Native Americans. What was, from a European point of view, the beginning of a golden age, was for most of the rest of humanity, the beginning of an imperial nightmare that has not quite come to an end. The success of European science, after the sixteenth century, when compared to that of other regions, owes quite a bit to the abundance of wealth available to fund it. But that wealth had to come from somewhere, and one of the places it came from was from the Islamic lands. Military and economic decline entailed cultural decline as well. That seems a more realistic explanation for the decline of Islamic science than the arguments of one Sufi mystic, however widely read.
This essay is part of a series; the previous essay can be found here.
Daniel Halverson is a graduate student studying the History of Science and Technology. He is also a regular contributor to the PEL Facebook page.