The Myth of Galileo

William E Carroll writes:

Last week, the BBC reported on the letter signed by 67 professors at the Sapienza University of Rome, which urged the cancellation of a speech by Pope Benedict because of remarks he made about Galileo in 1990. The BBC noted that, whereas Pope John Paul II had formally admitted that the Earth moved and that the Church had erred in condemning Galileo, the then Cardinal Ratzinger had cited the comments of the philosopher of science, Paul Feyerabend, that the Inquisition’s actions in the Galileo Affair were “reasonable and just”.

In fact, Ratzinger had not endorsed Feyerabend’s historical judgment so much as reflected on the fact that some scholars had come to see dangers in modern science and technology. As he has done since becoming Pope, he warned against identifying reason with only what science affirms.

The signatories said they were “humiliated and offended” by what the Pope had said more than 17 years ago. In the midst of the spiralling controversy, he cancelled his appearance, sending instead only the text of his remarks. And so a legend was perpetuated.

The humbled Galileo, kneeling before the cardinals of the Inquisition, being forced to admit that the Earth did not move – one could not ask for a clearer image of blind faith, biblical literalism and superstition. It occupies a prominent place in mythology of the history of religion and science. Indeed, the modern world is determined to resist any challenge to the view that Galileo was persecuted by the Church as part of an attempt to thwart the rise of science.

When John Paul II spoke before the Pontifical Academy of Sciences in 1992, he noted that the Inquisition had failed to distinguish properly between particular interpretations of the Bible and questions which in fact pertained to scientific investigation. He also observed that an unfortunate consequence of the condemnation of Galileo was that it had reinforced the myth of an incompatibility between faith and science. That such a myth was alive and well was apparent in the headline on the front page of the New York Times: “After 350 Years, Vatican Says Galileo Was Right: It Moves.” John Paul’s remarks would rectify “the persecution of the Italian astronomer and physicist for proving the Earth moves about the Sun”. The BBC’s report last week was in this vein.

The story of Galileo is often used as evidence for the view that the Church has been hostile to science and that what it once taught it now denies. In debates about cloning or stem-cell research, proponents often compare opposition to such research to the Inquisition’s treatment of Galileo. But are these ideological uses of the legend justified by the historical record?

Galileo’s telescopic observations served him well in his defence of a moving Earth. But we must distinguish between arguments in favour of a position and arguments that prove a position to be true.

Galileo did not prove that the Earth moves about the sun. In fact, Galileo and the Inquisition accepted the prevailing ideal of scientific demonstration which required that science be sure and certain knowledge in terms of necessary causes, not the conclusions of hypothetical or probabilistic reasoning which today we accept as science. Galileo himself did not think that his observations provided evidence to prove that the Earth moves. He hoped eventually to argue conclusively from the fact of ocean tides to the double motion of the Earth as the only possible cause, but he did not succeed.

Cardinal Bellarmino, Jesuit theologian and member of the Inquisition, told Galileo in 1615 that if there were a true demonstration for the motion of the Earth then the Church would have to abandon its traditional reading of those passages in the Bible which appeared to be contrary. But, in the absence of such a demonstration, and in the midst of the controversies of the Protestant Reformation, the cardinal urged prudence: treat Copernican astronomy simply as a hypothetical model which accounts for the observed phenomena.

It was not Church doctrine that the Earth did not move. If the cardinal had thought that the immobility of the Earth were a matter of faith, he could not argue, as he did, that it might be possible to demonstrate that the Earth does move.

The theologians of the Inquisition and Galileo adhered to the principle that, since God is the author of all truth, the truths of science and the truths of revelation cannot contradict one another. In 1616, when the Inquisition ordered Galileo not to defend Copernican astronomy, there was no demonstration for the motion of the Earth. Galileo expected that there would be such a demonstration; the theologians did not. It seemed obvious to the theologians that the Earth did not move and, since the Bible does not contradict the truths of nature, the theologians concluded that the Bible also affirms that the Earth does not move.

The Inquisition did not think that it was requiring Galileo to choose between faith and science. Nor did he.

Remember that Galileo and the Inquisition thought that science was absolutely certain knowledge, guaranteed by rigorous demonstrations. Being convinced that the Earth moves is different from knowing that it moves.

What the Inquisition did – unwisely ­– was to subordinate the interpretation of certain passages of the Bible to a geocentric cosmology, a cosmology which would eventually be rejected. Such an action is really the opposite of the domination of science by religious faith.

In 1632 Galileo published his Dialogue Concerning the Two Chief World Systems, in which he supported the Copernican “world system”. As a result, he was charged with disobeying the 1616 injunction not to defend Copernican astronomy. In 1633, the Inquisition required that he publicly and formally affirm that the Earth does not move. Galileo reluctantly acquiesced.

From beginning to end, the actions of the Inquisition were disciplinary, not doctrinal, although they were based on the erroneous notion that it was heretical to claim that the Earth moves. Erroneous notions remain only notions; opinions of theologians are not the same as Christian doctrine.

The notion of the Galileo affair as a central chapter in a long war between science and religion was strengthened by the 19th-century disputes over Darwin. The supporters of evolution were seen as modern Galileos; opponents as modern inquisitors. Opponents of the declaration of papal infallibility (1870) also invoked Galileo to demonstrate what they regarded as its absurdity. Had not popes solemnly proclaimed that the Earth does not move? Likewise, proponents of Italian unification clothed themselves in the mantle of Galileo.

There is no evidence that when Galileo acceded to the demand that he renounce the view that the Earth moves that he muttered under his breath, eppur si muove, “but still it moves”. What continues to move, despite evidence to the contrary, is the legend that Galileo represents reason and science in conflict with faith and religion.

William E Carroll is Thomas Aquinas Fellow in Theology and Science, Blackfriars, Oxford