A namesake, Richard Christie, has asked me an interesting question at Open Parachute and as I decided to give a somewhat extensive answer I am posting it here. Richard first asked my opinion on the issue of the Catholic Church actively suppressing various lines of scientific enquiry. I asked him to be more specific as I knew of no case where the Church had succeeded in suppressing a scientific line of enquiry. Richard quite correctly pointed out that actively suppressing and succeeding in suppressing are actually two different things. He then suggested the Church’s inclusion of Kepler in the Librorum Prohibitorum, commonly called the Index, as an example of the active suppression of various scientific activities.

The whole question of the Index and the inclusion of scientific books, in particular books on heliocentrism, in it is both a very complex one and a very emotional one that is usually dealt with in a very superficial manner in discussions about science and religion and although I can’t even attempt to give a complete answer in a blog post I will try to at least touch upon many of the factors involved.

The first thing that needs to be considered is the question of the censorship of books in general in the 16th and 17th centuries something that is almost always ignored in discussions of the Index. The Catholic Church was by no means the only authority that tried to control the printing and distribution of books, in fact for most of the 16th and 17th century nearly all political authorities, and it should be remembered that The Vatican was a major political force and not just a religious one, tried to exercise this control through systems of licensing and bans. The printed word was regarded as dangerous and governments throughout Europe tried desperately to control it. I hadn’t realised until I started thinking about writing this post how similar the situation in those days with the newly invented medium, the printed book, is to our current situation with politicians of every hue trying to find ways to control and censor the Internet. I wont investigate the parallels further but I think the informed readers will see them for themselves. These attempts at control usually took the form of licensing, everyone wishing to print and publish a book, pamphlet or what ever being required to first obtain permission in the form of a license from the authorities. Anything printed without a license was automatically banned. Anything regarded as seditious for whatever reasons the political winds of the day decreed was potentially dangerous was denied a license. This would have meant that in a perfect world the authorities would have retained complete control over everything that appeared in print. This as we shall soon see was far from the truth.

In academic discussions of the law, the results of legislation are divided into good and bad laws. This division has little to do with the ethical or moral contents of a piece of legislation, although that also gets discussed, but rather with technical legal aspects of the law under discussion. A central point in such discussion is enforceability, a law that is difficult or almost impossible to enforce is per definition a bad law. In terms of enforceability the laws designed to ensure control of the printed word in the Early Modern Period were bad laws. Those wishing to publish seditious material, or anything that might be considered so, did not apply for a license in the first place but set up an underground press and published illegally. Of course people being what they are the attraction of the forbidden meant that the fruits of the underground presses enjoyed a massive popularity making something of a mockery of the attempt to censor them in the first place. If things got too hot for the operator of an underground press he just simply upped sticks and moved to another country where his products were not regarded as seditious. Often one government would actively encourage the seditious presses of a rival country for political reasons. The puritan agitators in England in the early part of the 17th century in the period before The English Revolution (or Civil War) moved their presses to the newly created United Provinces of the Netherlands whose Calvinist Government was sympathetic towards their cause. On the whole attempts to control or censor the printed word were a farce and totally ineffective, which however does not mean that those who got caught were not severely punished for their activities. Things were not any different for books or pamphlets placed upon the Church’s Index.

Having taken a brief look at the general background let us now turn to the attempt by the Catholic Church to control through censorship the literature on heliocentrism, I have generalised the original question concerning Kepler; in order to do this we need to be clear what exactly happened in 1616 and why. First of all what happened in 1616 actually had very little to do with science, this might seem like a rather strange statement given the fact that the books that were placed on the Index were books propagating heliocentrism but it is none the less true. What was a stake here was theology and not science and not even a conflict between theology and science but the question, who had the right to determine theological questions.

First of all one has to remember that at the beginning of the 17th century almost all educated people believed in the literal truth of the Bible, something that was not without problems as the Bible is often vague, confused and even contradictory, which means one first has to determine what the truth of the Bible is. The Catholic Church as an organisation had in its existence claimed the exclusive right to carry out this interpretation and its political power actually lay in this exclusive right. In this the Catholic Church does not differ substantially from other religious organisation and the intertwining of religion and politics to exercise control over the common folk is almost universal. Now the Bible often stands in conflict with reality and it is the job of theologians to sort out these conflicts. A theologian is not able to change reality so he must find a way to interpret the Bible that removes the conflict and by the beginning of the 17th century the Church’s theologians had become quite skilled at dissolving such conflicts. The relatively new heliocentric hypothesis potentially presented one such conflict as various passages in the Bible seemed to support a geocentric universe, which was not surprising as all the empirical evidence available up till that time also supported a geocentric universe. If the evidence for a heliocentric model had become stronger, which it did with the telescopic discoveries made between 1610 and 1613, then almost certainly the Church’s theologians would in the fullness of time have found a way to interpret the troublesome Bible passages in order to remove the conflict. As Galileo had been told by several of his influential Church friends, including Barberini the future pope, in 1611, as he was basking in the glory of his Sidereus Nuncius, urging him to be patient. Both the writings of Augustus Augustine and Thomas the two principal touch stones for Catholic theology provided possibilities for such interpretations. In fact Thomas had together with his teacher Albertus Magnus achieved just such a conflict solution with the scientific writings of Aristotle. However two people forced the issue and precipitated a minor theological crisis in the second decade of the 17th century, Galileo Galilei and Paolo Antonio Foscarini a Carmelite friar. The crime the these two men committed in the Church’s eyes was not that they propagated heliocentrism, which they did, but that they told the Church how to interpret the Bible and that was definitely a no, no.

I have already explained that the Church’s power was centred on their claim to the exclusive right to interpret the Bible, so Galileo and Foscarini telling them how to do so would have been bad enough at any time but you have to remember that they were in the middle of the Counter Reformation and on the eve of the Thirty Years War. One of the central claims of the Reformation had been that every man was entitled to read and interpret the Bible for himself without the authority of the Church, a claim that threatened to undermine the central power of the Catholic Church, so anybody coming along and trying to tell the Church how to interpret the Bible on any theme was treading on very dangerous territory especially as the Church was also a major absolutist political power in Italy at this time. Things took the inevitable course Galileo and Foscarini both got a rap on the knuckles and books claiming that the heliocentric hypothesis was true were placed on the Index, including Kepler’s.

This situation raises two immediate questions, what did the Church actually ban and why did they think it necessary to do so. What the Church banned was the heliocentric theory that is the claim that the universe is in reality heliocentric so all books making this claim were to be placed on the Index. The reasons for this ban are not so straightforward as they at first might appear. The potential conflict between heliocentricity and some passages in the Bible had existed since the Bible was collated in the 4th century, as Ptolemaeus had already discussed and rejected the heliocentric hypothesis in his Syntaxis Mathematiké in the 2nd century. Nobody had been really bothered by the potential conflict until Galileo and Foscarini had made it into a real conflict by suggesting a theological solution thus creating a real problem for the Church, which had three possible solutions. Firstly, they could take the course that would seem most logical to the modern mind and simply reinterpret the Bible to remove the conflict, this was of course, seen through the eyes of the Church in the 17th century, impossible. If they did so they would be admitting that Galileo and Foscarini were right and in admitting that a mere mathematicus could interpret the Bible giving up their exclusive right to do so, the basis of their power. They could of course ignore the whole thing and do nothing, again an impossible situation for the Church because then it would appear that they were incapable of solving the conflict i.e. of correctly interpreting the Bible. This process of reasoning led to the only possible conclusion that the Bible was right and the heliocentric theory was wrong and therefore may not be propagated and any books that did so must be banned. In his unconsidered and over hasty actions Galileo had forced the Church to ban the heliocentric theory.

Those who have been paying attention may have noticed that I have alternated between two different terms the heliocentric theory and the heliocentric hypothesis. This is neither sloppiness on my part nor an attempt to avoid repetition of words for reasons of style. This is very deliberate because they are actually two substantially different terms. The heliocentric hypothesis says that heliocentricity offers a possible model to explain the observed motion of the planets; it says nothing about the truth-value of this model. The heliocentric theory says that the universe is in reality heliocentric. In 1616 the Church banned the heliocentric theory but not the hypothesis. This might at first seem like splitting hairs but in reality it is a very important distinction. Astronomers were completely free to go on discussing and researching the possibility of heliocentricity but until they produced actual proof that the universe is indeed heliocentric they were not allowed to claim that it was. So in reality the Church was here not even attempting to actively suppress a line of scientific activity. As a side note it should be pointed out from an epistemological standpoint the Church was right to deny the correctness of the heliocentric theory at that time, which does not however excuse their primitive attempt to ban it.

It might be argued that the Church created this obvious loophole out of ignorance or by mistake but the historical evidence clearly shows this was not the case. Firstly the much maligned Roberto Bellermino wrote in his so-called Foscarini letter that should the heliocentric hypothesis be proved to be correct then the Church would have to re-interpret the Bible, showing that he was well aware of the difference between hypothesis and theory. Secondly, contrary to popular opinion, the main heliocentric text, Copernicus’ De revolutionibus, was not placed on the Index but only referred to the Index until corrected. This meant that all the passages claiming the reality of heliocentricity were to be removed. This was actually carried out and the De revolutionibus, with surprisingly few minor changes was released again for general consumption in 1622.

So what were the consequences of the Church’s ban on books containing the heliocentric theory, all in all very few. The Church managed to embarrass itself for the next 400 years and the astronomers got on with doing what they had been doing before Galileo tried his hand at theology. Kepler was at first worried about the consequences of having his book placed on the Index but his friends pointed out to him that this would actually make them more attractive, forbidden fruit. All of the astronomy books on the Index were actually readily available to scholars, all the ban meant was that they could not find them on open shelves but had to apply to read them and they would be duly delivered from the poison cabinet. Outside of Italy nearly all scholars just simply ignored the ban and Catholic astronomers didn’t even bother to correct their copies of De revolutionibus. One notable exception was René Descartes who held back the publication of one of his books on heliocentricity out of respect for his Jesuit teachers. This fact has a certain level of irony because as Descartes was exercising restraint the Jesuit astronomer Johann Adam Schall von Bell was teaching Copernican astronomy in China. Probably the major source through which scholars learnt about the Copernican theory in the middle of the 17th century was the textbook of Pierre Gassendi the professor for astronomy and mathematics at the university in Paris, like Descartes a product of the Jesuit education system. Gassendi’s book of course taught heliocentrism as a hypothesis. Within Italy things were slightly more critical and Italian astronomers trod somewhat more carefully. Their books on heliocentricity presented it as a hypothesis and included the information that the Church had ruled that it was not true. Two leading Jesuit astronomers Athanasius Kircher and Giovanni Riccioli were both reported to the Inquisition for sailing too close to the wind on the heliocentric theory but both were eventually cleared of suspicion.

In the end the Church took a long time to back itself out of the cul de sac into which Galileo and Foscarini had steered it but the consequences for the development of astronomy of placing pro-heliocentric books on the Index were negligible and it has even been argued that Bellarmino’s statement that a proof of heliocentricity would force the Church to re-interpret the Bible actually spurred Catholic and in particular Jesuit astronomers on to find the necessary proof.

I will close with a personal statement that ought to be totally superfluous but there are some people underway in the Internet who think that when one discusses heliocentricity and the Index if one doesn’t scream Church bad, Church evil whilst beating ones breast in best King Kong manner then one condones or even supports the Church’s censorship. For the record I vehemently oppose all forms of censorship not matter who exercises them.