On the whole in my activities as a historian of science I have mostly tried to avoid Galileo Galilei; as far as I’m concerned there are many much more interesting cases to be researched. Naturally as a historian of the early modern period I have long been aware of the main details of his life and scientific activities. Last year was The International Year of Astronomy in which I was intensively active and as the year was created to celebrate the 400th anniversary of Galileo’s first use of the telescope in astronomy I could not avoid reading a vast number of popular and semi-popular article about Galileo and his activities. Beyond this I was asked by a writer to recommend research literature for such an article and as a result I decided that I should read up on the newest research results concerning the Tuscan polymath, which I duly did.
Now anybody reading, in particular, the popular literature on Galileo with a half way critical mind will very rapidly become aware that it is all permeated with an incredible level of hyperbole, it would appear that Signor Galileo is superhuman. If we just take some of the statements from the, on the whole fairly good, Wikipedia article we have the following collection of exaggerated statements:
Galileo has been called the “father of modern observational astronomy” the “father of modern physics” the “father of science”and “the Father of Modern Science.” Stephen Hawking says, “Galileo, perhaps more than any other single person, was responsible for the birth of modern science.”
At the bottom of the article we have the following title: The Person of the Millennium: The Unique Impact of Galileo on World History.
I have also in my reading come across the following claims: “G is the inventor of the scientific method”, “G was the first to apply mathematics to science”, “G discovered the first mathematical law of science” and so on and so forth…
The image of Galileo Galilei has been inflated like a dirigible airship that floats above the early modern period obscuring the efforts and achievements of all the other scientists, his shadow only being broken by the light of that other god of science Isaac Newton. Unfortunately this image is total bullshit and its propagation leads to a major distortion in our understanding of the historical development of science. In what follows I shall be pulling the plug, extracting the stopper, puncturing the balloon and letting the gas out so that one can begin to judge Galileo’s achievements from a sensible standpoint.
Central to this image of Galileo is his supposed uniqueness; through his ‘once in human existence genius’ he single-handedly created modern science, the scientific method, observational astronomy and physics. This view is pure rubbish and is only possible if one totally ignores his contemporaries. Of these Johannes Kepler, Thomas Harriot, Christoph Scheiner, William Gilbert, Christoph Clavius, Francoise Vieta, Isaac Beeckman and Simon Stevin are all scientists who are on a level with Galileo both from their abilities and also from their scientific achievements and contributions. I think, in real terms, any attempt to sort scientists into some sort of league table is a waste of time and bound to fail but if forced, I would rank at least three of the above list above Galileo in terms of their ability and two of them in terms of their contribution to the development of science. There was absolutely nothing unique about Galileo.
On the specific claims, modern physics, for exampled developed out of the work of Galileo, Gilbert, Kepler, Stevin and a whole boat full of minor figures many of whom do not get the credit they deserve. The same applies to observational astronomy that grew out of the contributions of Galileo, David Fabricius, Harriot, Simon Marius, Christoph Scheiner and another boat load of so called minor figures. When people talk of modern science what they actually mean is a combination of modern physics, astronomy and ‘the scientific method’. Having dealt with physics and astronomy we will now turn to the latter.
The claim that Galileo invented the scientific method is not just wrong it’s grotesque! The scientific methodology that is utilised in Galileo’s work on mechanics was known to and used explicitly by Greek scientists such as Ptolemaeus and Archimedes. It was discussed and used extensively by Islamic scientists such as Al Haytham. It was also extensively discussed, but little used, in the High Middle Ages by Robert Grosseteste and Roger Bacon. Of Galileo’s contemporaries both Gilbert and Stevin had both published significant scientific works utilising the scientific method, as Galileo was still an unknown, unpublished professor of mathematics in Northern Italy. Gilbert’s De magnete, which is based not only on his own empirical scientific research but also on that of several other minor figures in the second half of the 16th century, was regarded as one of the most important guides to scientific methodology throughout Europe in the first half of the 17th century. Both Kepler and Galileo were fans of Gilbert’s work but Galileo criticised it as having too little mathematics, which brings us to our next point: Galileo, science and mathematics.
Now it is generally agreed that the so-called mathematisation of nature is a central feature of the creation of modern science but that this is largely attributable to Galileo is a myth. Like the scientific method the use of mathematics in science has its roots in the work of Ptolemaeus, Archimedes and other Greek scientists. Islamic opticians and astronomers mathematised extensively and Grosseteste and Bacon also praised it as the basis of good science. In modern terms the mathematisation of physics begins in the High Middle ages in the work of the Oxford Calculatores and the Paris physicists, whose work was known to and developed upon by Galileo. In the 16th century Italian mathematicians such as Tartaglia and Benedetti laid the foundation of much of Galileo’s work on mechanics, foundations that were also well known to Galileo. Both Kepler and Stevin were producing modern mathematical science long before Galileo and it is usually Kepler who is given the credit for the first mathematical law of nature for his inverse square law of the propagation of light; a law that inspired Ismael Boulliau to the first formulation of the inverse square law of gravity.
To give a couple of examples of actual developments in physics attributed falsely to Galileo, he is supposed to have been the first to note that bodies of unequal weight fall at the same speed in a vacuum when in fact this was first noted by Simon Stevin. Galileo is also credited with the foundation of hydrostatics in modern physics where again it was the significantly different approach of Stevin that was developed further by others in the 17th and 18th centuries. Lastly it is often claimed that Galileo provided Newton’s first law, The Law of Inertia. Now Galileo did take a first step along the road from the mediaeval concept of impulse towards inertia but his concept was still handicapped by a belief in the Aristotelian concept that natural motion is circular motion. This blemish is explained away by claiming that Descartes modified the Galilean concept from whence Newton took it over. Newton did indeed take over the inertia law from Descartes but Descartes had taken it not from Galileo but from Isaac Beeckman who had formulated it fully correctly in the form used by Newton
Having deflated the image of Galileo I will say that he was one of the leading scientists at the beginning of the 17th century who made significant contributions to the development of several disciplines but he was only one of them. All of this naturally raises the question as to how Galileo’s image became so inflated. In the 17th century he enjoyed a sort of pop star status for a time as a result of his astronomical discoveries, which faded at the end of the century as wow-look-sensationalism in astronomy was replaced by the more scientific approach of astronomers such as Hevelius and Cassini. The rest of his scientific endeavours were not so successful. Contrary to received opinion it was the works of Kepler that brought the breakthrough in the acceptance of the heliocentric world-view and not Galileo’s Dialogo, which by the way ignored Kepler’s work. Galileo’s work in mechanics was known but not particularly regarded and was largely superseded by Newton’s work at the end of the century. In the 18th century his light dimmed even further, so where does the inflated god of science come from?
In truth Galileo was canonised by the Catholic Church! The inflation of his image was a result of Galileo being declared the main scientific martyr in the greatest myth of the history of science, the totally fictitious ‘War Against Science’. Galileo’s inflated image is largely a product of the 19th century and the perception that he had been sacrificed on the altar of religion. A second factor comes into the picture as a result of the fact that most popular history of science is not written by scientists, this is that Galileo was an excellent writer. Reading Kepler’s works is hard work even for his fans. Scheiner’s Rosa Ursina is as observational astronomy way beyond anything that Galileo produced but even astronomers found it too tedious to read. I could make similar comments about almost my entire list of Galileo’s contemporaries added to the fact that several of them wrote works that can only be read by mathematicians. Galileo wrote wonderful polemic texts* that are still a joy to read for anybody with a good general education. This same factor of readability has led to an over emphasis of the significance of both Bacon and Descartes in the history of 17th century science, but that’s another story. The figure that people celebrate is the literary scientific martyr and not the real scientist from the 17th century.
My deflation also raises the question as to whether other gods of sciences could and should also be deflated, what’s with Newton, Darwin, Einstein? John Wilkins at Evolving Thoughts has at regular intervals posted articles on his blog dislodging Darwin from his pedestal and relocating him into the main stream of 19th century biology and I assume he will continue to do so. Patricia Fara has written an excellent book, Newton: The Making of a Genius, which documents the inflation of Newton’s image throughout the 18th and 19th centuries. I haven’t come across any similar work on Einstein but if it doesn’t exist already it’s only a matter of time before one or more get written.
Science is a collective enterprise and even people such as Galileo are only members of the collective and what ever they may or may not have achieved they very rarely earn the epitaphs that are given them by writers more interested in documenting sensation than the slow irregular evolution of science.
*An after thought: My friend Pierre who unlike me is a real Galileo expert as well as being a science event organiser and science publicist thinks that Galileo can be credited with a genuine achievement, he was the worlds first science publicist and very good at it!