On the Golden Age of Islamic Science

During what we sometimes call the “Middle Ages,” science in the Abbasid Caliphate was flourishing: scholars from diverse backgrounds gathered in centers like Baghdad, where they made fantastic advances in mathematics, astronomy, chemistry, and physics. When these scientific achievements eventually reached Europe, they helped spark Europe’s Scientific Revolution.

As beneficiaries of their discoveries, we are indebted to these Medieval Muslim scientists. And so, I think, we owe it to them to understand their story – to understand the social and political forces that enabled them to make their discoveries.

In his book Islamic Science and the Making of the European Renaissance, the historian George Saliba traces this scientific golden age to the late Umayyad Caliphate, during a period not normally associated with any kind of scientific research. Saliba bases his theory on the Kitāb al-Fihrist, a chronicle of the history of Islamic culture composed during the 10th century CE by the scholar Ibn al-Nadim. Saliba maintains – following al-Nadim – that the process of translating Ancient Greek, Persian, and Indian texts began when the Umayyad Caliph Abd al-Malik instituted a number of governmental reforms, one of which was the translation of what is called the diwān into Arabic. The diwān consisted of codes and handbooks written in each region’s native language and which taught diwān officials the skills they needed to govern their respective region. These skills included basic accounting, land surveying (which involved geometry), and astronomy.

13th century illustration depicting a public library in Baghdad, from the Maqamat Hariri. Bibliotheque Nationale de France
A 13th century Iraqi illustration of The House of Wisdom in Baghdad, which was the intellectual center of the Islamic Golden Age


Traditionally, diwān officials came from the region they governed and spoke the local language: those who ruled over Greek-speaking Syria were Syriac Greeks and those who ruled over Persian territories were Persian. They had to be from their region of governance because only those who spoke the local language could understand the local diwān. But the reforms of al-Malik changed this: when the diwān was translated into Arabic, these officials lost their unique hold over the governance of these territories, because now any Arabic-speaking citizen was eligible for the job.

The translation of the diwān to Arabic thus led, according to Saliba, to a new competitive environment in the court of the Caliph. In order to maintain power, Persian and Syriac Greek government officials, who also served as court astronomers, physicians, and mathematicians, had to gain a competitive edge over the many Arabs who could now participate in government. Because the Arabs who already served in court now had a chance at upward mobility, they also needed a way to prove their worthiness to the Caliph. The competitive edge these officials looked for, Saliba argues, was knowledge.

The science and mathematics of the diwān were relatively simple: they were only as complicated as they needed to be for administrative affairs. But the court officials knew of more advanced texts by the ancients. These were texts on medicine and astronomy that were occasionally referred to in the diwān as resources one could consult should one want to solve some more complicated scientific problem. Until that time, diwān officials never had reason to seek those texts out. But with the new competitive environment in the court of the Caliph, Saliba maintains that these officials now had incentive to look for the more advanced works of the ancients. If they could translate and master the material contained therein, they could out-compete those who vied for and were now eligible to take their positions.

Indeed, soon after the translation of the diwān into Arabic, government officials from all backgrounds began to seek out the more advanced scientific and mathematical texts of the Ancient Greeks, Persians, and Indians. Many of these government officials commissioned expeditions to every corner of the Caliphate to recover such works. Unbeknownst to them, when they found Ancient Greek texts rotting in the vaults of the Byzantine Empire, they fashioned what would later become the world’s main lifeline to Ancient Greek thought.

Within only one to two generations, court officials became versed in the works of Aristotle, Ptolemy, Galen, and other ancient thinkers. Though they had initially also sought out Persian and Sanskrit books after the translation of the diwān into Arabic, they quickly shifted most of their attention to the Greek tradition, since it was, they felt, more comprehensive than that of the Indians or Persians and also had a broader range of applications.

An early 13th century Syrian illustration of Socrates and his students.

As court officials and the scholars they hired translated the works of the Greeks, they also looked for and corrected mathematical and empirical errors in the original texts. Saliba suggests that this attention to detail may have been driven by competition for high reputation in the court of the Caliph: the translators didn’t want someone to find mathematical or empirical mistakes in their work and thereby discredit their abilities as translators or scientists. In many ways, this was a medieval predecessor to modern peer review.

The need for accuracy wasn’t just driven by the competitive environment of the court. More religious and traditional thinkers looked with suspicion at the Greek texts being translated and the “foreign sciences” they inspired. There are records of these more traditional thinkers trying to belittle the value of Greek-inspired thought, trying instead to bolster the worthiness of studying “native” or “traditional” sciences like linguistics, the Quran, literature, and poetry. There was thus, Saliba argues, even greater pressure on the scientists (who were by no means non-religious, but were open to non-religious methods of inquiry) to do a good job of transmitting and developing the sciences of the Greeks, especially when the worldview suggested by their work could be interpreted as contradicting Islam.

This process of checking the credibility of ancient texts led to a number of important technological and mathematical innovations. For example, in order to get more accurate checks on the empirical claims of ancient astronomers like Ptolemy and his medieval Muslim successors, there was a push for more precise astronomical readings. This led to the building of the world’s most sophisticated observatories and the most accurate astronomical tables ever recorded. At the same time, mathematicians updated and refined the mathematics of Ancient Greek texts, using their more advanced knowledge of trigonometry and the numerical-decimal system they inherited from the Indians.

What followed was an outpouring of monumental works of science and mathematics. The reception of Greek science was so sophisticated that the early edits and modifications to Greek texts developed into an entire genre of systematic scientific skepticism. This genre was called the shukuk or “doubts,” and included Ibn al-Haytham’s Doubts Concerning Ptolemy and al-Razi’s Doubts About Galen. This flourishing of scientific, philosophical, and mathematical thought reached its apex in the Bayt al-Hikma, or House of Wisdom, which was founded in Baghdad by the fifth Abbasid Caliph Harun al-Rashid in the 8th century CE. There, scholars from all over the Caliphate – Muslims, Christians, and Jews; Arabs, Greeks, and Persians – all worked to translate and refine the works of the ancients. They developed new mathematics, composed new astronomical and medical treaties, and worked at reconciling Islam with Greek philosophy. The House of Wisdom produced some of the greatest thinkers in history: al-Khwarizmi, who invented algebraal-Haytham, who developed the first mathematical theory of optics, and al-Biruni, who used an astrolabe and his knowledge of mathematics to accurately calculate the size of the earth.

An illustration from al-Birunu's account of the different phases of the moon
An illustration from al-Birunu’s account of the different phases of the moon.

When we reflect on these spectacular achievements, we can’t help but wonder: How did Europe, so long an intellectual backwater, later get so far ahead of the Muslim world in science and mathematics? According to what Saliba calls the traditional narrative of the Islamic Golden Age, a decline in scientific research in the Muslim world followed two events: the “takeover” of religious thinking in the 12th century CE that was precipitated by the popularity of al-Ghazali‘s anti-science treatise The Incoherence of the Philosophers, and the Mongol siege of Baghdad in the 13th century CE, which saw many of the works produced and kept in the city’s libraries thrown into the River Tigris. But as Saliba points out, exceptional research continued in the Muslim world long after both al-Ghazali and the Mongol invasion, and so the traditional narrative does not offer a satisfactory explanation for the seeming decline in the region’s scientific output.

Saliba’s alternative explanation is that Muslim science didn’t actually decline, so much as get eclipsed by European science. As Europe gained far greater economic prosperity than the Muslim world during and after the European Renaissance, its scientific output grew enormously. With greater prosperity, more people could conduct research and more money could be invested in science. As Saliba suggests, this was partly due to the European discovery of the Americas. We might add to this equation the rise of Europe’s banking economy.

Though Europe certainly far surpassed the Muslim world in scientific output, it is important to keep in mind that without the efforts of medieval Muslim scholars, Europe may not have experienced its outpouring of scientific thought during the Renaissance and later the Enlightenment. When contact opened up between Europe and the Muslim world in the late Middle Ages, by trade through Venice and through the military conquest of Muslim-controlled Spain and Sicily, the texts of the Ancient Greeks trickled into Europe along with the works of the Muslim scholars who had translated and expanded upon Greek thought. When these texts were translated into Latin, they spread relatively quickly through Europe – faster than they could spread in the Muslim world –  due to the The Printing Revolution that followed the Europeans’ invention of the printing press. This is perhaps as important as economic prosperity in trying to understand why European science quickly outstripped that of the Muslim world.

The first page of Copernicus' De revolutionibus orbium coelestium, which marked the beginning of the European Scientific Revolution
The first page of Copernicus’ De revolutionibus orbium coelestium, which marked the beginning of the European Scientific Revolution

Considering this view of the apparent decline of science in the lands of Islam, we can see why it’s fruitless to ask, as some have done, what went “wrong.” We should instead study the conditions that led to the flourishing of scientific research in the medieval Muslim word in the first place and ask what lessons we can draw from this remarkable period in history. If Saliba’s account is right, then I can think of at least one lesson to learn here: If we look back at this period, it becomes clear how important it is for there to be significant incentives – be they financial, social, or both – for scientists to constantly push at the edges of the known. If the officials in the courts of the Umayyad and Abbasid Caliphates hadn’t looked to more advanced science and mathematics as a way to secure their positions in court, then the books of the Ancient Greeks may have continued to rot in the vaults of Byzantium, eventually fading entirely, and neither the Muslim world nor Europe after it may have been able to revitalize those texts for posterity.

And this, I think, is a lesson for science today. If we don’t have incentives to become scientists and scholars, to devote ourselves to the expansion of the corpus of human knowledge, then who will?

5 thoughts on “On the Golden Age of Islamic Science

    1. Hi Saleem, thank you! The Golden Age of Islamic Science is an absolutely crucial period in the history of science, which is often ignored or misrepresented. The period tells us a lot about the conditions under which science can thrive, particularly because it happened at a time when scientific research in the rest of the world declined or stopped completely. As I understand it, the period is taught and remembered in Muslim countries, but it’s not something that’s traditionally taught elsewhere. And this is a shame, because, as I described here, the Islamic Golden Age is also central to European scientific and cultural history.

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