Enlightenment Roots – Science


At nine o’clock the next morning the teacher of Italian was announced. I saw a man of respectable appearance, polite, modest, speaking little but well, reserved in his answers, and with the manners of olden times. We conversed, and I could not help laughing when he said, with an air of perfect good faith, that a Christian could only admit the system of Copernicus as a clever hypothesis. I answered that it was the system of God Himself because it was that of nature, and that it was not in Holy Scripture that the laws of science could be learned.
(Casanova’s memoirs, To Prison and Paris, Chapter 1)

‘Enlightenment Roots – Introduction’ attempted to outline the significance of the Enlightenment and briefly indicate the pre-Enlightenment view of the world.  This article will now consider the challenge posed to Aristotelean scholasticism by the emergence in the seventeenth century of the scientific revolution, with a particular focus on Astronomy, Francis Bacon, René Descartes and Isaac Newton.

Crucial to the scientific revolution, particularly Physics, was Astronomy.  Mankind has always speculated about the nature of the cosmos, both from an ontological perspective, being the source of numerous religions and creation myths, and from a practical perspective in terms of the measurement of time and navigation.  For over one and half thousand years geocentrism, the belief that the Earth was the centre of the universe, was the settled view of Christianity.  In fact, it was not until the nineteenth century that the Catholic church dropped entirely its resistance towards heliocentrism, the belief that the Earth orbits the sun.  That man should see himself as the centre of the universe was not, as is popularly believed, testament to his arrogance and pride but, in fact, quite the reverse.  If God, who was perfection and at the summit of the Great Chain of Being, inhabited the heavens then the Earth and man, by being at the centre of the cosmos, were always at the most distant point from that perfection (with hell being at the centre of the Earth).  The heavenly bodies themselves were assumed to be immutable and everlasting, qualities that constituted part of God’s perfection. This significance, therefore, entailed that Astronomy was a field of study held in particularly high regard and one of enormous importance to scholasticism.  To question the order of the cosmos was to stray into extremely sensitive territory.

Heliocentrism was proposed as early as the third century BC by the Greek Aristarchus but it was Ptolemy’s geocentric model which gained favour, partly because of its accuracy in calculating the positions of the planets and therefore its usefulness to travellers.  From the fifteenth century onwards, however, the ancient Ptolemaic model began to be undermined by the growing influence of the neo-Pythagorean quantitative conception of the universe as opposed to the scholastics’ qualitative conception, and by the work of scholars such as Copernicus, Kepler and Galileo.  The qualitative conception, as we have seen, viewed the universe in terms of divine qualities and perfections, such as love, wisdom, immutability and so forth.  The quantitative conception, instead, discerned the hand of God in ratios, proportions and geometrical harmonies.  For such scholars, the book of nature, not the book of scripture, was the way to reveal God’s work and the perfection of his design.  This was illustrated most dramatically through Kepler’s heliocentric laws of planetary motion, which Kepler achieved by dint of analysing Tycho Brahe’s observations of the movements of Mars in one of the most laborious feats in scientific and arithmetical history.  For a while the geocentric and heliocentric theories coexisted without a great deal of controversy.  Problems arose at the beginning of the seventeenth century when Galileo defended the heliocentric theory against scripture, notably that the Earth was set in place by God and could not be moved (Psalms and Chronicles). Unwisely, he asserted that heliocentrism did not contradict the Bible and, moreover, he disputed that the Bible was an authority on science.  He was accused of reinterpreting the Bible and the case was set before the Inquisition who found against heliocentrism in 1616.  In 1633, following upon further controversy, Galileo was placed under house arrest until his death in 1642.  Beyond the specific dispute of heliocentrism itself, Galileo also fundamentally challenged Aristotelian scholasticism by rejecting qualitative perfections.  He distinguished subjective secondary qualities, which were dependent upon human perceptions (and included most Aristotelian qualities), from objective primary qualities, such as dimension, shape and number. His observations of the planets were a case in point.  Using a telescope of his own making he revealed that the heavenly bodies were far from the perfect, immutable spheres deduced by Aristotelian scholasticism but objects that were subject to erosion and change.  For Galileo, God’s creation could only be known through empirical observation and inductive reasoning using the tools of mathematics, not deductive reasoning based upon authority.

One of the most influential figures in the development of science was someone who, ironically, contributed very little of note to scientific knowledge. Francis Bacon (1561-1626) was born to a well-connected family whose father, Sir Nicholas Bacon, was a Tudor politician and the Lord Keeper of the Great Seal.  He grew up in a period when the printing press had stimulated a growth in education that extended beyond the confines and institutions of religion.  Consequently, Bacon was one of an increasing number of educated men who began to concern themselves with the operations of the natural as well as the supernatural world.  To get to grips with the natural world he decided it was necessary to jettison the dominant Aristotelean deductive tradition, which for him comprised little more than sophistry and rhetorical tricks, a concern for words rather than genuine enquiry, and adopt a new approach to learning.  The approach he promoted was nothing less than the scientific method as we understand it today.  Outlining his vision in The New Organon (1620), Bacon argued that it was man’s Christian duty to reduce human suffering and increase well-being and to do so through the development of useful knowledge.  The key to acquiring such knowledge was to study nature directly rather than through the filter of human and scriptural authority, and to utilise experiment and inductive reasoning, building generalisations upon evidence derived from systematic observations of particular instances.  Sources of error and individual human bias would be combatted by divorcing religious speculation from the study of nature and through careful testing.  Unlike the disputatio of scholasticism, scientific endeavour would be cooperative.  Knowledge would be acquired surely and cumulatively.  In Bacon’s vision, progress would not be dependent upon the genius of particular individuals but communities.  As we shall see, the establishment of such secular ‘learned societies’ along the lines proposed by Bacon was to play a major role in the development of science from the second half of the seventeenth century onwards.

Bacon may have questioned the practical usefulness of scholasticism but he didn’t challenge its philosophical underpinnings or its theological claims.  The same could not be said of René Descartes (1596 – 1650), a philosopher, mathematician and scientist who, along with his followers, represented a direct and profound intellectual assault upon the Aristotelean project.  He wrote at a time when the question of how to determine truth had acquired particular urgency.  Firstly, the Protestant Reformation was establishing alternative authorities with their own alternative claims to truth to those of Rome.  Secondly, a revival of ancient Greek scepticism was casting doubt on the very possibility of obtaining certain knowledge about anything.  The formulation for any criterion of truth, for example, could be immediately undercut by asking what the criterion of truth was for that criterion of truth and so on ad infinitum.  Descartes response was to out-sceptic the sceptics and in so doing proposed solutions that radically opposed those of scholasticism.

Descartes rejected as inadequate the attempt to establish knowledge on the basis of human or supernatural authority. His ambition, instead, was to build knowledge on much stronger foundations, and to do so he employed a method dubbed ‘hyperbolic doubt’, famously illustrated with cogito ergo sum (‘I think therefore I am’).  It may be possible to doubt everything else, but it was not possible to doubt the existence of a thinking mind.  This was a criterion for certain knowledge.  Reason, the thinking mind, was thus elevated above authority and faith.  Knowledge acquired by the senses failed the test of hyperbolic doubt.  However, Descartes was able reinstate the value of sensory perception after he proved the existence of God (the proofs for which, unsurprisingly, have always been hotly contested).  God, being benevolent, is not a deceiver and if he has furnished mankind with senses and data to be sensed then there has to be an external world.  The senses must therefore offer at least a potential source of knowledge.  Although Descartes concluded that deductive reasoning provided the most reliable basis for knowledge he did not dismiss the value of inductive reasoning as has been sometimes suggested.  Indeed, he regarded inductive experimentation as an important way of verifying deductive theory.  Descartes distinguished between material existence, whose essence was best understood objectively as extension in space (which was also the view of Galileo), not subjectively through the senses, and immaterial existence that does not occupy space, such as thought, mind or soul. He concluded that the physical world operated through matter communicating force to matter and that only matter could affect matter.  God, he maintained, set matter in motion and His fixed, immutable will entailed that it operated according to equally fixed, immutable laws.  Material existence, such as the body, worked like a machine and the purpose of science should therefore be to understand its mechanisms. As far as the mind was concerned, the ghost in the machine, Descartes held to a rationalist theory of innate ideas whereby knowledge of reality was ultimately derived from ideas with which the mind was ready stocked (ideas such as height, width and depth), not the senses, which only conveyed a shadowy version of reality.  Of course, this dualistic system that posited the existence of separate material and immaterial entities was faced with reconciling how a material substance, such as the body, that obeyed only mechanical, physical laws, could interact with an immaterial substance such as the mind, a problem, the mind-body problem, which has haunted philosophers to the present day.

Where did Descartes leave scholasticism? Well, gone was the Aristotelean division of substance into matter and form.  Gone was the concept of final ends and divine purpose as an explanation for the character of things.  Gone was human and scriptural authority over nature.  So radical were these ideas that Descartes was accused of deism (and even atheism).  The Christian world was a world of the supernatural, of miracles and divine intervention.  The Christian God was very much hands on, an almost tangible presence in people’s lives.  The God of Descartes, by contrast, was a disappointingly abstract and distant being.

While on the continent Descartes’ rationalist philosophy was demolishing the theoretical underpinning of scholasticism, in England a more Baconian and empirical scientific culture was taking root, albeit one that utilised the mathematics of Descartes.  Although scholasticism continued to dominate the universities throughout Europe, and was to continue to do so until the end of the eighteenth century, other institutions of learning developed, notably, in 1660, the Royal Society (or, to give it its full title, the Royal Society of London for Improving Natural Knowledge).  Increasing numbers of men were actively engaged in exploring the natural world and took on board the vision of natural philosophy as promoted by Francis Bacon in his New Organon and his unfinished New Atlantis.  They began conducting their own experiments and meeting together to discuss them.  The foundation and activity of the Royal Society, particularly the publication of its journal Philosophical Transactions, greatly increased awareness of, and participation in, this new field of scholarly endeavour.  The Society’s motto, chosen by John Evelyn shortly after its founding, is ‘Nullius in verba’ (‘take nobody’s word for it’), clearly a snub to the principles of Aristotelean scholasticism: ‘It is an expression of the determination of Fellows to withstand the domination of authority and to verify all statements by an appeal to facts determined by experiment’ (The Royal Society website). Early contributors included such luminaries as Christopher Wren, Edmond Halley, Robert Boyle, John Wilkins and, of course, Isaac Newton whose Opticks was published in the Transactions in 1704.

By the time the Royal Society had published Isaac Newton’s Opticks, of course, Newton was already famous.  The crowning glory of the scientific revolution of the seventeenth century had been the publication in 1687, in Latin, of his three volume Philosophiæ Naturalis Principia Mathematica, overseen by Edmond Halley of the Royal Society.  The Principia outlined the three essential laws of mechanics which would become the foundation of modern Physics.  His discovery of gravity, however, was initially opposed by Cartesians (followers of Descartes) who rejected the idea of spooky effects at a distance.  But for Newton, without evidence, he was not going to attempt to explain why or how gravity operated.  He had shown that gravity existed and that its operation accounted for events in nature, such as Kepler’s laws of planetary motion.  He was not going to pretend to know more than that which the evidence allowed. Along with the discovery of calculus and his investigations into the nature of light, Newton had transformed man’s understanding of the universe.  His accomplishment astonished the educated world, his reputation as the greatest genius who had ever lived being immortalised in Alexander Pope’s epitaph: “Nature and nature’s laws lay hid in night;/ God said ‘Let Newton be’ and all was light.”. Based upon observation of nature, experiment, mathematics and inductive reasoning, Newton’s achievements were a massive vindication of the new ideas that were transforming the intellectual landscape both of Europe and North America.

(Painting – Foundation of the Academie de Sciences et l’Observatoirein 1666 (1675) by Henri Testelin)

Note: references to Casanova’s memoirs relate to the revised unabridged Arthur Machen English translation (Gutenberg project)

Dave Thompson (2018)


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