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Home , Aristotelian physics

Aristotle and Medieval Universities

Rob Iliffe Introduction

• This lecture deals with the () of and , Greeks who lived nearly 2500 years ago. • Their legacy lasted in Western philosophy for 2000+ years • We will look at the other-worldly, largely mathematical philosophy of Plato and the ‘empirical’, observational science of Aristotle. • Concludes with discussion of role of Aristotelian philosophy in medieval and early modern European universities. Plato (427-347 BCE)

• Student of Socrates and teacher of Aristotle; founded Academy in Athens. • Early dialogues concerned life and teachings of Socrates. • Key later works were the utopian (or dystopian) Republic, and the creation myth Timaeus. • Key idea was of ‘Forms’ or ‘ideas’ (e.g. in Phaedo) – • these are perfect exemplars of characteristics such as beauty, virtue and justice (and of course, love), • which supposedly exist in some reality lying beyond the senses. • We can only perceive these dimly, as if we are in a Cave able only to see the shadows of the brightly lit Forms Roman bust of Plato, copy of original made for Athenian Academy (c. 370 BCE) The Significance of

• Plato influenced by the numerical philosophy of Pythagoras • In the Republic he was highly dismissive of the Arts, esp. poetry, which was to be banned for provoking unnatural emotions. • Instead one should study arithmetic, plane and solid geometry, astronomy and harmonics – which aim at what is eternal. • After this one should study philosophy. • But key claim was that mathematics is both beautiful and useful for training the mind, hence necessary for the education of the soldier-philosophers who were guardians of the Republic. Aristotle (384-322 BCE)

• The most significant figure in Western thought until the mid-C17th. • Sent to Athens in 367, where he studied under Plato in the Academy. • When Plato died in 347 Aristotle left Athens, and in 343 became tutor to Alexander (later ), son of Philip of Macedonia . • Returned to Athens, and when Athens came under Macedonian rule he founded the in 335, a rival school to the Academy. • Aristotle composed numerous works in his lifetime on an astonishing variety of subjects, notably , ethics, , , natural history, and logic; also on poetry and .

Anti-Plato • Plato’s philosophy was an inspiration and a foil for Aristotle. • Plato’s emphasis on mathematics and abstract theoretical learning was countered by Aristotle’s qualitative physics • Who argued that the empirical observation of in this world, with an overwhelming emphasis on sense-experience, was crucial for learning about the natural world. • Hence his extraordinary empirical studies of nature, including works on embryology and of animals in their natural habitat. Aristotelian Method • Rational humans whose senses were working properly could not be mistaken about what they experienced. • Human senses were adequate for grasping individual ‘facts’ about Nature • However, sense-perception by itself was insufficient for knowledge, since one needed to move from single observations of ‘particular instances’ to more general observations. • This was done by ‘induction’, or logical generalization, which led to universal and necessary truths about the natural world. • Aristotle’s approach to the Nature/Art distinction underpinned the view that artifice could not aid the understanding of Nature. • This would be overturned in of early C17. Substance and form • Aristotle’s ‘forms’ are different from Plato’s, since he held that the form of something cannot be separate from its material structure. • There are ‘substantial’ and ‘accidental’ forms • Substantial forms are the source of organizational unity in material things, esp. living things. • The soul, e.g., was the organizing principle of a human being. • ‘Accidental’ forms were qualities that underwent change, or that can be lost or gained, such as ‘wisdom’, ‘strength’ or ‘colour’. • This was extremely useful to medieval theologians who used it to gloss the Christian doctrine of transubstantiation. The terrestrial sphere

• Terrestrial sphere below sphere of the was the eternally existing place of change and mortality or corruption (i.e. death) • Aristotelian was useful for Christians who wanted to place humans at the topological and functional centre of the cosmos. • Geocentric observations (i.e. that the Sun rises and sets) were consistent with sensory observations of the heavens • Passages in the major sacred Christian text, the Bible, particularly the Old Testament, were overtly geocentric. The within 7 ; from 11th century Ms. of Bede’s De Natura rerum. The World as Motion

• Motion (kinesis) a broad, general term, understood in terms of ’potentiality’ and ‘actuality’. • Aristotelian understood the terrestrial world as one of ubiquitous ‘work-in-progress’, i.e a world of natural things operating by various means to produce motions that realize their . • This was a world of , in opposition to the timeless and perfect of the heavenly sphere. • This view applied to babies/humans, and seeds/trees. • In Politics, he argued that humans could only fulfil themselves in the city, since they were ‘political (sociable, i.e. of the polis) animals’ Aristotle’s teleological philosophy • Aristotle placed great emphasis on causes, arguing that four elements composed this world - Water, , , Earth. • Things in this world were composed of various mixtures of these elements, each of which tended to move towards its ‘natural’ place, which was its goal or . • Items composed mainly of earthy or watery elements tended to go downwards, while objects composed of fiery or airy elements sought to rise to the heavens. • One explained why natural events happened through appeal to the natural ‘goals’ or ‘tendencies’ of physical and organic entities. • ‘Violent’ or ‘unnatural’ motion was imposed by some external .

The Geocentric Aristotelian Universe • Earth was at the centre of a finite and full (plenist) cosmos • The was perfect and unchanging • The Moon, Sun and other planets revolved in invisible ‘crystalline’ spheres that guided their orbits around the Earth • Heavenly bodies were composed of 5th element, ‘quintessence’; • These bodies have ‘animating souls’ or ‘intellects’ to guide them. • The celestial world was ‘superior’ to the terrestrial world, and it influenced events on the Earth – • Hence the Aristotelian system gave strong support to astrology Geocentric system with ten celestial spheres, from Peter Apian, Cosmographia, (Antwerp, 1539) Geocentric Cosmos, Bartholomeu Velho, 1568 Aristotelian Physics • A was impossible – Nature ‘detested’ a Vacuum • Similarly, there was no such thing as an indivisible entity (), since this would imply a vacuum. • The Aristotelian philosophy, explained various phenomena such as motion, and light and sound in terms of an aether – a medium that permitted the translation • It was impossible for objects to move, and for light and sound to be experienced, without this medium. The Islamic Commentators

• In the C9 CE, major translation process took place in Baghdad, rendering Greek originals into Arabic with commentaries. • Al-Kindi wrote a major commentary on Aristotelian Logic, while • Al-Farabi wrote influential commentary on Aristotle’s . • The physician (c. 980-1037), and esp. the philosopher (1126-1198) composed major expositions of , effectively Islamicizing many of his doctrines. Universities and the first Christian commentators

• Translation of Aristotelian texts and Islamic commentaries into Latin was co-extensive with growing confidence of Christian states, • And with appearance of the universities in 12th and 13th centuries. • Aristotelianism was introduced into the first universities • Many major Western commentators – such as Roger Bacon and Robert Grosseteste – built on the work of Islamic commentators. • To some extent they Christianized his works but his philosophy posed many for Christian thought. Reconciling Science and Religion in the Medieval World • Medieval universities witnessed tensions between the high regard for Aristotle in Arts faculties and more suspicious attitude held by Augustinian scholars in Theology departments. • Aristotelianism was condemned in the late 13th century by the Archbishop of Paris, Etienne Tempier • 1. for its eternalism which denied the specificity and uniqueness of God’s creation), • 2. its astrological determinism (which detracted from human freewill), • 3. its strong links between form and substance (which denied human immortality), • 4. and its excessively high regard for human Reason. Aristotle and Plato in the 15th and 16th centuries • Despite criticisms, Aristotelianism vied with the Platonic philosophy to be the ‘official’ philosophy, winning out by the C14th. • Aristotle’s natural philosophy emphasised that the goal of physics was to explain natural phenomena through appeal to physical causes - • Natural philosophy was generally held to be superior to mathematics, which merely described the external measurements of things. • Many internal contradictions and empirical problems appeared within the Aristotelian system in the 16th and 17th centuries. • The status of mathematics, and of ‘mixed mathematical ' increased substantially within both Protestant and Catholic universities in the later C16th and early C17ths.