by Matthew Cobb
The conflict between science and religion – conflict that occurs every time religion decides it has anything to say about the way the natural world functions – threw up some of its greatest and most tragic examples during the “Renaissance”. There are lessons here for today, in particular for those who believe that science and religion can coexist as they deal with completely separate worlds – this idea has its roots in this period of history.
The Renaissance of European culture that occurred from the 14th century onwards was a consequence of the growth of mercantile wealth in Northern Italy and Spain, of trade contact with the Far East and of the impact of the Arab world, which had extended its influence far into southern Europe. The Renaissance was marked by an explosion of cultural development, and a resurgence of the ideas of Aristotle, Galen and many other Ancient thinkers. For example, Leonardo’s suggestion that semen comes from the man’s brain can be traced directly back to the ideas of the school of Pythagoras in the 6th century BC, ideas that were kept alive and transmitted via the Arab world.
But although the Renaissance gave rise to a new spirit of openness and discovery in all realms of culture, it also saw Aristotle’s ideas about the natural world turned into a stifling orthodoxy that crushed initiative and investigation. All the key scientific developments of the 17th century, from astronomy to zoology, therefore involved a reaction against the dogmatic interpretation of Aristotle’s views.
This disastrous transformation of Aristotle’s ideas came about through the work of Thomas Aquinas, an Italian monk and philosopher who lived in the 13th century. At the time a number of Church theologians were influenced by the great Arab philosopher, Ibn Rushd (known in the West as Averroës), and argued that philosophy and faith were separate matters. This was dangerous for the Church, which knew that too much free thinking could undermine faith, and therefore weaken its power.
Aquinas found a solution: using Aristotle’s philosophical ideas, he argued that faith and sense experience were not separate as Averroës argued, but complementary. The facts of the natural world, Aquinas suggested, could be known by sense experience, while spiritual truths such as the Resurrection could be known only by faith. Aquinas gave the Church the best of both worlds: it could use the power of Aristotle’s philosophy to examine moral questions and to understand the natural world, but all matters of faith remained firmly in its hands.
This view, which became known as the “Thomist dogma” (after Thomas Aquinas), led the Church to defend and promote all of Aristotle’s ideas, including those that had no immediate impact on theological issues. Among the positions that came under the protection of the Church was Aristotle’s version of the common-sense impression that the Sun goes round the Earth, in which the various planets and stars moved on gigantic, insubstantial “spheres”. To challenge Aristotle was to challenge part of the Church’s theology, whatever the truth might be.
In 1633, 350 years after the death of Aquinas, Galileo found himself caught in this trap when he published proof that the Earth goes round the Sun. The Church could have accepted such a sun-centred vision of the universe without damaging its theology (it eventually did… in 1992!), but once it had decided to approve Aristotle’s theory of the spheres, defending its authority became more important than defending the truth. And any decline in its authority could weaken its hold on the minds, money and actions of millions of people.
It is not clear exactly why the Church ended up obsessing about the Earth-centred universe, rather than, say, Aristotle’s theory of the generation of animals, which – at exactly the same time – was equally under attack, not only from Protestants such as Swammerdam and Steno (who shortly afterwards converted to Catholicism), but also from Italian Catholics like Francesco Redi and Marcello Malpighi. And even before Galileo found evidence for the heliocentric view of the universe, he had already made a major attack on Aristotle’s world view, in his famous work on falling bodies, in particular his suggestion that – contrary to both Aristotle and common sense – objects with different masses fall at exactly the same speed, without the Church threatening him.
In fact, as a NASA webpage devoted to Galileo points out , the two question of falling bodies and the nature of the universe were intimately linked: “The problem, as [Galileo] saw it, was that the Aristotelian theory of motion, which referred all motion to a stationary earth at the center of the universe, made it impossible to believe the earth actually moves. Galileo went to work to develop a theory of motion consistent with a moving earth.”
When you actually do the experiment of dropping a feather and a lead ball, which have different masses, the ball drops faster because the resistance of the air is greater on the feather. Galileo recognised this, and concluded in his law of falling bodies that in a vacuum all objects, regardless of their weight, shape or specific gravity, are uniformly accelerated in the same way, and that the distance fallen is proportional to the square of the elapsed time (summary taken from here). Pretty smart, eh?
In 1971, David Scott and James Irwin spent a week on the surface of the moon, on the Apollo 15 mission. Towards the end of their final moonwalk, in homage to Galileo, David Scott showed that in a vacuum, a feather and a hammer will fall at the same speed. As Mission Controller Joe Allen put it rather drily in the “Apollo 15 Preliminary Science Report”:
“During the final minutes of the third extravehicular activity, a short demonstration experiment was conducted. A heavy object (a 1.32-kg aluminum geological hammer) and a light object (a 0.03-kg falcon feather) were released simultaneously from approximately the same height (approximately 1.6 m) and were allowed to fall to the surface. Within the accuracy of the simultaneous release, the objects were observed to undergo the same acceleration and strike the lunar surface simultaneously, which was a result predicted by well-established theory, but a result nonetheless reassuring considering both the number of viewers that witnessed the experiment and the fact that the homeward journey was based critically on the validity of the particular theory being tested.”
Want to be really impressed? Watch it – it really is quite astonishing.