God’s Philosophers: a book review

God’s Philosophers by James Hannam (2009)

I recently read James Hannam’s God’s Philosophers, which is the story of the Medieval ideas that led up to modern science, told largely through short biographies of major and minor figures (this relates to my previous two posts about when and why science began, as well as to my three posts about science and Dante).

Farming in the 15th Century

The early Middle Ages was, to a large extent, a struggle to build a more productive agricultural system (since Europe had lost access to the rich grain-fields of North Africa that had fed the Roman Empire). The later Middle Ages, however, saw an explosion of new ideas. Some of these ideas came from the Muslim world, but many were entirely original.

The Age of Cathedrals: Bourges (begun c. 1195, finished c. 1230)

Hannam briefly surveys Medieval mathematics, logic, medicine, astronomy, astrology, alchemy, and engineering. Roger Bacon (1214–1292) and Richard of Wallingford (1292–1336) are discussed in some detail. The former wrote on optics and the theory of science, while the latter did work in trigonometry and designed an elaborate astronomical clock. Clocks were to replace living things as metaphors for the operation of the Universe.

Richard of Wallingford using a pair of compasses

Hannam also has a chapter on the Merton CalculatorsThomas Bradwardine (c. 1290–1349), Richard Swineshead (fl. 1340–1355), and William Heytesbury (c. 1313–1373). As well as contributing to logic, these scholars anticipated Galileo’s application of mathematics to physics, proving the mean speed theorem. In France, Nicole Oresme (c. 1325–1382) developed an elegant graphical proof of this theorem, as well as doing work in astronomy and introducing the bar graph. Ironically, it was the later Humanists who, inspired by the glories of ancient Greece and Rome, discarded some of these advances (the same source of inspiration also led to a decline in women’s rights, as Régine Pernoud has pointed out).

Merton College, Oxford (Michael Angelo Rooker, 1771)

Hannam finishes his book with the stories of Kepler and Galileo. These are better known than those of the Medievals, but the myths surrounding Galileo seem to be as persistent as those about the so-called “Dark Ages.” Hannam’s treatment is necessarily simplistic and brief, but he does point out Galileo’s debt to Oresme and the Merton Calculators. For readers specifically interested in Galileo, the best introductory book is probably Galileo’s Daughter by Dava Sobel, with Finocchiaro for follow-up.

Although Galileo pitted the modern Copernicus against the ancient Ptolemy, Tycho Brahe had already suggested a hybrid system, which was only later proved wrong

Hannam concludes “It would be wrong to romanticise the period and we should be very grateful that we do not have to live in it. But the hard life that people had to bear only makes their progress in science and many other fields all the more impressive. We should not write them off as superstitious primitives. They deserve our gratitude.

See also this review in Nature of Hannam’s book (“God’s Philosophers condenses six hundred years of history and brings to life the key players who pushed forward philosophy and reason”), this review by a Christian blogger (“In God’s Philosophers James Hannam traces medieval natural philosophy—and some of the other disciplines we’ve come to think of as scientific, such as medicine—through the reign of Plato and Aristotle to the discoveries of Kepler and Galileo”), and this excellent review by an atheist historian (“… the myth that the Catholic Church caused the Dark Ages and the Medieval Period was a scientific wasteland is regularly wheeled, creaking, into the sunlight for another trundle around the arena. … Hannam sketches how polemicists like Thomas Huxley, John William Draper, and Andrew Dickson White, all with their own anti-Christian axes to grind, managed to shape the still current idea that the Middle Ages was devoid of science and reason.”). Hannam has also responded comprehensively to this negative review by Charles Freeman. I disagree with Freeman, and am giving Hannam’s well-researched and readable book four stars. My only real quibble is Hannam’s somewhat biased view of the Protestant Reformation.

* * * *
God’s Philosophers by James Hannam: 4 stars


The thermometer

The earliest form of thermometer was invented by Galileo between 1592 and 1603. The basic idea was refined by various scientists over the centuries, since temperature measurement is a very important activity. Daniel Fahrenheit (he of the temperature scale) invented the first mercury-in-glass thermometer somewhere between 1714 and 1724.

Other temperature-measuring technologies were to follow. In 1871, in his Bakerian Lecture, Sir William Siemens proposed the resistance thermometer: “it is shown that, in taking advantage of the circumstance that the electrical resistance of a metallic conductor increases with an increase of temperature, an instrument may be devised for measuring with great accuracy the temperature at distant or inaccessible places, including the interior of furnaces, where metallurgical or other smelting-operations are carried on… In measuring furnace temperatures the platinum-wire constituting the pyrometer is wound upon a small cylinder of porcelain contained in a closed tube of iron or platinum, which is exposed to the heat to be measured.

Practical versions of this proposed device were operational by 1887. The alternate technology of the infrared thermometer for medical use goes back to a 1934 paper by Hardy and Muschenheim.

The most fun way to measure temperature is probably the inaccurately named “Galilean thermometer,” with its colourful glass balls floating in a liquid column:

Angels and (Foolish) Demons

I recently got around to watching the 2009 film Angels and Demons. Like The Da Vinci Code, this is a very silly film, with both the science and the history being wildly wrong. Galileo’s condemned book was widely printed outside Italy, for example. Publishers of the day were too discreet to plaster BANNED IN ITALY! READ IT FOR YOURSELF! on the cover, but the controversy was nevertheless a publisher’s dream. Even today, the house of Elsevier (who originally printed the book) prides itself on the connection (see photo of Elzevir edition by Angelina Ward below). The book has also kept up with the times; it can be read electronically.

Galileo did not, as the film suggests, argue for elliptical planetary orbits. Kepler did that, and failing to believe Kepler was one of Galileo’s biggest mistakes (had he believed Kepler, Galileo knew enough mathematics to see what ellipses and parabolae had in common, and might have gone on to formulate a theory of gravity).

The movie gives the viewer some wonderful images of Rome, but here the facts are wrong too. Raphael was never buried anywhere but in the Pantheon, for example. The book tells us that “Bernini’s Fountain of the Four Rivers glorified the four major rivers of the Old World: The Nile, Ganges, Danube, and Rio Plata” – even though the Río de la Plata is in South America. And the list goes on. Among other things, Bernini did not place the “West Wind” marker on St Peter’s Square, nor is that marker distinct from the other fifteen:

“What’s new, Buenos Aires?
I’m new, I wanna say I’m just a little stuck on you.
You’ll be on me too…
And if ever I go too far,
It’s because of the things you are.
Beautiful town, I love you…
Río de la Plata, Florida, Corrientes, Nueve de Julio,
All I want to know…”

Possibly Dan Brown did indeed go a little too far here.

Why did Science begin?

Following on from my previous post about the origin of science in the 12th century, one might ask why the influx of ideas from the Muslim world led to such a scientific explosion in Europe (I’ve been having some Facebook discussions on this). The philosopher Alfred North Whitehead (1861–1947), in his Science and the Modern World (1926, pp 15–16), suggested (perhaps surprisingly) that the credit lay with medieval theology:

I do not think, however, that I have even yet brought out the greatest contribution of medievalism to the formation of the scientific movement. I mean the inexpugnable belief that every detailed occurrence can be correlated with its antecedents in a perfectly definite manner, exemplifying general principles. Without this belief the incredible labours of scientists would be without hope. It is this instinctive conviction, vividly poised before the imagination, which is the motive power of research:—that there is a secret, a secret which can be unveiled. How has this conviction been so vividly implanted on the European mind?

When we compare this tone of thought in Europe with the attitude of other civilisations when left to themselves, there seems but one source for its origin. It must come from the medieval insistence on the rationality of God, conceived as with the personal energy of Jehovah and with the rationality of a Greek philosopher. Every detail was supervised and ordered: the search into nature could only result in the vindication of the faith in rationality. Remember that I am not talking of the explicit beliefs of a few individuals. What I mean is the impress on the European mind arising from the unquestioned faith of centuries. By this I mean the instinctive tone of thought and not a mere creed of words.

In Asia, the conceptions of God were of a being who was either too arbitrary or too impersonal for such ideas to have much effect on instinctive habits of mind. Any definite occurrence might be due to the fiat of an irrational despot, or might issue from some impersonal, inscrutable origin of things. There was not the same confidence as in the intelligible rationality of a personal being. I am not arguing that the European trust in the scrutability of nature was logically justified even by its own theology. My only point is to understand how it arose. My explanation is that the faith in the possibility of science, generated antecedently to the development of modern scientific theory, is an unconscious derivative from medieval theology.

There are perhaps three relevant theological ideas in the medieval theology to which Whitehead refers. The first is the idea of the Universe as rational, because it is created by a rational God. Such an idea is implicit in, for example, the Timaeus of Plato, which suggests that eternally existing Platonic solids were used by the Creator as the shapes for the different kinds of atom:

The belief in rationality also prompted some good medieval work in the field of logic. However, Whitehead suggests that medieval theology also incorporated “the personal energy of Jehovah.” In particular, the “scrutability of nature” – the idea that Nature is knowable – is implicit in the medieval idea of Nature as a written book, intended to be read. Galileo famously quoted Tertullian (c. 160–225) on this point:

God is known first through Nature, and then again, more particularly, by doctrine – by Nature in His works, and by doctrine in His revealed Word.” (Tertullian, Against Marcion, I:18; Galileo, Letter to the Grand Duchess Christina of Tuscany, 1615)

Galileo later expanded on the mathematical language in which he thought the “book” of Nature was written:

La filosofia è scritta in questo grandissimo libro che continuamente ci sta aperto innanzi a gli occhi (io dico l’universo), ma non si può intendere se prima non s’impara a intender la lingua, e conoscer i carattere, ne’ quali è scritto. Egli è scritto in lingua matematica, e i caratteri son triangoli, cerchi, ed altre figure geometriche, senza i quali mezi è impossibile a intenderne umanamente parola; senza questi è un aggirarsi vanamente per un oscuro laberinto.

[Science] is written in this grand book – I mean the universe – which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it; without these, one is wandering around in a dark labyrinth.” (Galileo, Il Saggiatore, 1623, tr. Stillman Drake)

[This passage has often been quoted, although today we would instead speak of equations and other mathematical constructs.]

Finally, there is the idea that the studying the Universe has value. Whitehead refers to belief systems which considered the world to be unintelligible. There were also other belief systems which devalued even the attempt to understand the world. The Neo-Platonists, for example, focussed their attention on mystical appreciation of the divine things “above,” which left little room for detailed study of the mundane and physical down here “below” (although it did encourage the Neo-Platonists to do mathematical work). The medievals flirted with Christian forms of Neo-Platonism, but the belief that God had created the Universe always gave the mundane and physical its own inherent value, as far as they were concerned.

The Stoics, on the other hand, believed in a cyclic Universe which was periodically destroyed, only for history to repeat itself in exact detail, like a serpent eating its own tail. There is a degree of pointlessness in such a viewpoint which perhaps discourages scientific investigation. Certainly, neither the Neo-Platonists nor the Stoics built the kind of scientific structure that Europeans began to construct in the 12th century.

Today, of course, the rationality and knowability of the Universe are largely taken for granted (except, perhaps, by Postmodernists), and more people are involved in the scientific enterprise than ever before. The spectacular success of science has made the rationality and knowability of the Universe so obvious, in fact, that it is difficult to comprehend a time, thousands of years ago, when most people thought that unpredictable chaos was all there was.

See also “When Did Modern Science Begin?” by Edward Grant [American Scholar, 66 (1), Winter 1997, 105–113].

Galileo’s view of the Moon

These historic sketches of the moon were published by Galileo in his Sidereus Nuncius or Starry Messenger of 1610, not long after building his famous telescope. This is where modern astronomy began. The photo below (by Michael Dunn) shows a replica of Galileo’s telescope:

See also this 3-minute documentary on YouTube.