Peter Abelard

The Stanford Encyclopedia of Philosophy called Peter Abelard "the pre-eminent philosopher and theologian of the twelfth century. The teacher of his generation, he was also famous as a poet and a musician." Seems like someone we should get to know a little better.

Born about 1079 in the Duchy of Brittany to a minor French noble and soldier, Peter proved to be a clever boy who was encouraged by his father to study the Liberal Arts. He chose the path of academic over his father's military career. Around 1100 he went to Paris and started calling himself Peter "Abelard." The reason for the name change—and the etymological source of the surname itself—is unclear. In Paris he studied under one of the great French teachers of the age, William of Champeaux. Abelard's own account of his time there claims that his master's attitude turned to hostility when Abelard proved to be smarter and better at debate than William. Abelard began to make a career out of arrogantly quarreling with anyone and everyone.

He decided he should become the master, and so he established his own school, first away from Paris at Melun, and then between 1102 and 1104 moving nearer Paris to provide competition for the schools there. He found willing students, but the stress of running a school himself led to a nervous breakdown, so he went home to Brittany for several years.

He returned to Paris after 1108, setting up a rivalry between his school and that of William of Champeaux. One of the big philosophical quarrels was over the topic of universals. Abelard defeated William in a debate on the topic so efficiently that he was in line to be offered a position at the school at Notre-Dame, but William's influence managed to prevent Abelard from being allowed to teach in Paris. Abelard returned to Melun to run his school, but did manage to move it to a hill overlooking the left bank of the Seine, overlooking Notre-Dame.

He attended theological lectures by Anselm of Laon, but was unimpressed and started lecturing on the book of Ezekiel himself, but Anselm forbade him from teaching his way, so Abelard abandoned Laon for Paris. In 1115, he was offered the position of master of the Cathedral school of Notre-Dame.

At this point, he was a well-established and popular teacher in his late 30s. Into his social sphere came a girl of about 15 named Heloise d'Argenteuil. We need to talk about her next.

Nature vs. Nurture

The English polymath Francis Galton (1822 - 1911) framed the debate calling the terms

...a convenient jingle of words, for it separates under two distinct heads the innumerable elements of which personality is composed. Nature is all that a man brings with himself into the world; nurture is every influence that affects him after his birth.

He could not have known that in the year of his death a French manuscript from six centuries earlier would surface that used the same terms (although it spelled one of them "Noreture"). It tells the story of Cador of Cornwall, whose just-born daughter would not be allowed to inherit property and title, so he decides to raise her as a boy. Named Silentius (Silence), she turns out to be the equal of any boy in various chivalric pursuits.

Throughout her life there are two personifications, Nature and Nurture, who address Silentius with their opinions on her lifestyle. Nature tries to convince her to act like the woman she was born as. Nurture supports Silentius' desire to be what she wants to be. Silentius knows that if she reveals herself to be a woman, her parents will be dishonored.

Ultimately, in a Twelfth Night-style twist, the "young man" travels to the court of King Eban, whose queen, Eufeme, falls in love with the talented and beautiful young Silentius. Silentius, not willing to betray the king by having an affair, and of course not willing to have her true sex discovered, rebuffs the queen's advances. The queen, enraged, decides silence must die, and sends her/him off to capture Merlin, an impossible task, since Merlin "cannot be captured by a man."

Silence succeeds, and brings Merlin back to court. Merlin reveals that Silentius is actually female. Silence reveals that the queen was in love with her, etc., causing King Eban to execute Queen Eufeme for faithlessness and cruelty and make the now-named Silentia his new queen.

I have severely abbreviated the story, which has many more details and events. The ultimate lesson is that Nature wins out. This may be perfectly natural for a culture that believed some were born royal and some were not, and there was a difference between the two.

Here's a question that might be raised after this story: why would anyone try to (or need to) capture Merlin? Because Merlin was a mad beast running wild, that's why. If you didn't know that about Merlin, you should read tomorrow's post.

Ibn Khaldun

Ibn Khaldun (alias Abū Zayd ‘Abd ar-Raḥmān ibn Muḥammad ibn Khaldūn al-Ḥaḍramī) was born 27 May 1332 in Tunis. He was a Muslim Arab from a well-to-do family whose later works, both autobiographical and historical, provide modern scholars with some of the best available information on his time and the Ottoman Empire. When he was 17 years old, his parents both died from the Black Death. They had enabled him, however, to study with some of the finest teachers available, which helped determine the course of his life.

Part of that life was spent in government service, as described in this post from a few months ago. He wrote about the world around him, giving us insight into the history of his part of the world here.

His most enduring contribution to scholarship may have been the Muqaddimah, (Arabic "Prologue"). In it we find the first literature on sociology. He introduces the concept of social asabiyyah, (Arabic "tribalism" or "social cohesion" or "nationalism"); asabiyyah is either rising or falling, and societies go through these cycles. He points out that dynasties usually have the seeds of their own downfall, becoming complacent in their power and authority, allowing a peripheral asabiyyah unit to eventually take over. (A good example of this is how the "Mayors of the Palace" grew more powerful than their bosses, the Merovingian kings, and became the Carolingian dynasty.)

He also wrote about the relationship population growth and economic growth:

When civilization [population] increases, the available labor again increases. In turn, luxury again increases in correspondence with the increasing profit, and the customs and needs of luxury increase. Crafts are created to obtain luxury products. The value realized from them increases, and, as a result, profits are again multiplied in the town. Production there is thriving even more than before. And so it goes with the second and third increase. All the additional labor serves luxury and wealth, in contrast to the original labor that served the necessity of life. [source]

He also explained the basis of supply and demand:

The inhabitants of a city have more food than they need. Consequently, the price of food is low, as a rule, except when misfortunes occur due to celestial conditions that may affect [the supply of] food. [source]

Supply-side economics, the idea that lower taxes will lead to economic growth, also shows up in his theories:

It should be known that at the beginning of the dynasty, taxation yields a large revenue from small assessments. At the end of the dynasty, taxation yields a small revenue from large assessments. [Laffer Associates (November 11, 2003)]

This is known in modern times as the Laffer Curve, but even Arthur Laffer gives credit to Ibn Khaldun!

He spent much of his later life teaching. In 1384, the Egyptian sultan named him the Grand qadi (judge of Sharaia law) in Western Africa. Sadly, in that same year his wife and children died when their ship sank off Alexandria. His final years were spent writing his autobiography and teaching in Cairo. He died 17 March 1406.

All this talk of sociology brings up the question: what do sociologists think of the Middle Ages? How do they analyze cultural trends and practices centuries removed from being able to observe medieval society? There are different approaches, which I'll talk about next.

De Gradibus

De Gradibus (Latin: Concerning degrees) was written by the Father of Arab Philosophy, Al-Kindi (801-873CE). In it, he applies mathematics to medicine, demonstrating a method he invented to determine the proper strength of a drug for a patient. Also, he discusses the degrees of the phases of the moon and how they help a physician to determine the most crucial days of a patient's illness.

When it was translated into Latin, the complex mathematical reasoning made it difficult for Western Europeans to grasp. Roger Bacon appreciated his approach, and endorsed it thusly:

The degree can only be determined by the method taught by Al-Kindi’s De gradibus, one extremely difficult and almost entirely unknown among Latin physicians of these days, as everyone is aware. Whoever wants to become perfect in this philosopher’s art must know the fundamentals of mathematics, because the species of greater and lesser inequality, the species of ratios, and the very difficult rules of fractions are all used by this author.

Plinio Prioreschi, a 20th century expert on the history of medicine, credits Al-Kindi with the earliest attempt to quantify medicine.

Al-Kindi was heavily influenced by noted Greek physician Galen (129-216CE). The stereotype of a Muslim rejecting any non-Muslim source of knowledge is tossed out by Al-Kindi's approach to knowledge. He wrote:

We must not hesitate to recognize the truth and to accept it no matter what is its origin, no matter if it comes to us from the ancients or from foreign people. My purpose is first to write down all that the ancients have left us on a given topic and then, using the Arabic tongue and taking into account the customs of our time and our capacities, to complete what they have not fully expressed.

How did Arabic works come to be available to European scholars. Was it haphazard, or was there a deliberate move to share knowledge. Tomorrow we will learn about Gerard of Cremona, and for a double treat, we will also talk about Gerard of Cremona. (Not a typo.)

Al-Kindi

Abu Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (801-873CE) is called the Father of Arab philosophy. Born in Kufa and educated in Baghdad, he was instrumental in the translation of many Greek scholarly texts into Arabic. (Remember that a lot of classical scholarly knowledge came to Western Europe via Arabic translations.) He is also credited with introducing Indian numerals (what we mistakenly think of as Arabic numerals) into the Arab and western world.

He was a polymath who contributed to many fields, although he did not always find the scientific truth.

In astronomy he followed Ptolemy's geocentric theory of the solar system, and he was certain the planets followed circular orbits in obedience to God.

He was a chemist who debunked the idea of alchemy turning base metals into gold or silver. He was the first to distill pure ethanol, with which he created several perfumes. He also created cosmetics and pharmaceuticals, and wrote a book on the chemistry of perfume.

A recently discovered book of his in Istanbul, entitled (in English) A Manuscript on Deciphering Cryptographic Messages shows that he was a pioneer in cryptography with the first known explanation of how to decipher encrypted messages by analyzing the frequency of letters.

He wrote on pollution, environmentalism, and meteorology, and explained tides as a result of heating and cooling.

He published 15 treatise on music theory—five of which have survived—including the first known written use of the term "music" (musiqia); he urged the use of music in therapy.

In optics, he explained that both the eye and the object seen must be linked by a transparent medium (air) filled with light. He criticizes Anthemius of Trailes for reporting that sunlight could be focused in war to cause opposing warships to burst into flame. Anthemius did not witness it himself. Al-Kindi performed experiments to be certain this would actually work.

His theory that time, space, motion, and bodies were not absolutes but relative to other objects and the observer puts him closer to Einstein than to Galileo and Newton.

Although his belief that philosophy could support theology was contested by many Arabic scholars who followed him, his writings laid the groundwork much of Arabic philosophy to come.

He also applied mathematics to pharmacology, which I'll talk about tomorrow.

The Liar Paradox

Medieval philosophers categorized several logic puzzles as insolubilia, unsolvable things. Probably the most common of these was (and still is*) the Liar Paradox.

Consider the statement "I am lying." If I am truly lying at that moment, then what I just said was true. If the statement is therefore true, however, then to say "I was lying" would be a lie. So which is it?

One 20th century philosopher used Jean Buridan (c.1300-c.1361, mentioned elsewhere in this blog) to claim that it wasn't really a paradox. Arthur Prior said it wasn't really paradoxical because every statement includes an assertion of its own truth. The statement "I am lying." is therefore taken as true—it carries its own truth independent of other sentences or context— and considering it a paradox is an unnecessary complication.

Buridan actually used the Liar Paradox to prove the existence of God. He put forth two statements:
"God exists."
"None of the sentences in this pair is true."

The only consistent way to assign truth values, that is, to have these two sentences be either true or false, requires making “God exists” be true. In this way, Buridan has “proved” that God does exist. [Internet Encyclopedia of Philosophy]

This particular paradox first appears in the middle of the 4th century BCE. Eubulides of Miletus made a list of seven puzzles, one of which was “A man says that he is lying. Is what he says true or false?” His commentary on whether it is true or false is lost to time.

*Those readers of a certain vintage will remember the Star Trek: The Original Series episode "I, Mudd" in which a controlling super-robot is rendered useless by its inability to process the two statements "Everything Harry Mudd says is a lie." followed by Mudd saying "I am lying."

Wheel of Fortune

A 12th-century depiction of the Wheel of Fortune
from the "Garden of Delights" book by Herrad of Landsberg

The Wheel of Fortune is a familiar concept to many these days because of a popular game show, but the name and idea originated a lot earlier than the 20th century.

Human beings recognized long ago that luck was a dish served in one of two flavors, and that one never knew what flavor one was going to get. Life had its ups and downs, and this became represented as a circle of possibilities. This was similar to the wheel of the Zodiac, turning throughout the year and bringing with it changes in life. At some point, however, the Wheel of Fortune (in Latin, the Rota Fortunæ) began to be represented in a Ferris Wheel configuration, so that the "ups" and "downs" could be portrayed visually.

At the top of the wheel is a man at the peak of good fortune: he is portrayed as a king. The wheel turns constantly, however—Boethius points out in his Consolation of Philosophy that, should the wheel stop turning, then she is no longer Fortune: this changeability is fundamental to what she does. Therefore (in this clockwise-turning representation), on the right side you see the one who was formerly on top, sliding down; near the bottom, his crown has fallen off. All is not dire, however, for on the left you see that fortune is turning better for someone else, who is ascending and will some day be on top.

The concept existed before Boethius. An astrologer of the 2nd century BCE, Vettius Valens, refers to the Zodiac as the wheel of fortunes, and a Roman playwright of the same era, Pacuvius, puts Fortuna on a spherical rock that constantly rolls by chance. Chaucer also mentions Fortune's wheel when, in "The Monk's Tale," he recounts multiple stories of men whose fortunes went from good to bad.

Boethius

Boethius (left, with numbers from India)
debating Pythagoras (right, with an abacus)
while Arithmetic looks on

Boethius has been mentioned in passing before for his writing. An early philosopher whose works were very important to the Middle Ages, in life he was an important public servant from a noble family who rose very high before he fell.

Anicius Manlius Severinus Boethius was born about 480 to a prominent family that had produced a couple emperors; his father became a Roman consul in 487 but died shortly thereafter, leaving Boethius to be adopted by the aristocrat and historian Symmachus. Symmachus and Boethius were fluent in Greek, which might have figured into their execution—but we are getting ahead of ourselves.

Boethius went to work for Theodoric the Great, and some of his actions on behalf of the King of the Ostrogoths have survived in the records.

• Procuring or producing a waterclock for Theodoric to give to Gundabad of the Burgundians.
• Finding a lyre player to perform for King Clovis.
• Investigating irregularities in Theodoric's paymaster.

In his famous work De consolatione philosophiæ ["The Consolation of Philosophy"], which he wrote in prison, he says that his greatest accomplishment was getting his sons, Boethius and Symmachus, appointed co-consuls in 522.

Boethius did so well in his career that he was made magister officiorum ["master of duties"], responsible for overseeing all government services. That's probably where the trouble started. Kings and emperors can be mistrustful of those around them with too much power—even if the emperor gave him the power in the first place. Boethius was put in charge of reconciling the differences that had grown up between the Western Roman and Eastern Byzantine Empires. His political powers and education and ability to speak Greek (rare in the West) made him ideally suited for this. He was accused (falsely) of treasonous dealings with the Eastern Emperor Justin I against Theodoric. For this he was exiled, then executed. His adoptive father Symmachus was later put to death on the charge of collusion with Boethius to overthrow Theodoric—a charge which seems unlikely.

He was executed in 525, but his writings survived. He wrote many books, including translations of Aristotle's works on logic; Boethius' translations were the only access to Aristotle's logic available to western Europe until the 12th century. He also produced De arithmetica on the four uses of arithmetic: arithmetic, geometry, music, and astronomy.*

The Consolation of Philosophy is believed to have been written while he was in exile. It covers many topics, one of which gave the modern era the title of one of its most popular game shows. But that's a story for tomorrow.

*These are the four parts of the quadrivium, taught in medieval universities; it is likely that the curriculum was arranged thus because of Boethius.

A King, a Cardinal, and a College

Sancho in a contemporary manuscript

King Sancho IV of Castile (1258 - 1295), also known as Sancho the Brave, ruled the combined Iberian kingdoms of Castile, León, and Galicia for a little over ten years. Although his father wished Sancho's older brother, Alfonso, to take the throne, Sancho managed to gain support of the nobles. There was opposition to Sancho, but he offered a change from the elitist policies of his father, which helped maintain his support. Still, he could be harsh to opposition, such as when he executed 4000 followers of an opposition party.

Unfortunately, he could even be harsh to his own supporters. One of his most loyal supporters was Lope Díaz III de Haro—who was, among other things, Sancho's brother-in-law—but Sancho killed him in 1288 during an argument in which Lope threatened Sancho.

On 20 May 1293, King Sancho IV of Castile granted a royal charter to the Archbishop of Toledo to create a university in the city of Alcalá de Henares. It was called the Studium Generale ["School of General Studies"]. The archbishop, Gonzalo Garciá Gudiel, had been born in Toledo but studied at the University of Paris and become rector at the University of Padua. Wishing to create a university in the place of his birth, he convinced Sancho to give him some land and the charter. Sancho called him chanceller mayor en todos nuestros regnos ["great chancellor in all our realms"].

In 1499, an alumnus of the Complutense University (Complutum was the Latin name for Alcalá), Cardinal Cisneros, received a papal bull from Pope Alexander IV (seen here endorsing the Sorbonne) that allowed him to purchase more land for the expansion of the university. In the 16th and 17th centuries, students from all over Europe flocked to study there, in philosophy, canon law, medicine, philology, or theology. Famous alumni included Ignatius Loyola, founder of the Jesuits.

Complutense granted a doctorate to a female student in 1785, 135 years before Oxford even accepted female students! The university grew so large that, in the 20th century, it was moved to Madrid and given more buildings to accommodate its needs.

Peter Damian & Omnipotence

St. Peter Damian, letter writer

Peter Damian (c.1007 - 21 February 1072/3), the author of the Liber Gomorrhianus, was more than just a critic of priests' vices. He was a reformer whose piety caused him to be named a Doctor of the Church and to be placed in one of the highest levels of Heaven by Dante.*

He has a place in philosophy, however, due to one of the 180 letters he wrote. This particular one is called De divina omnipotentia ["Concerning divine omnipotence"]. In it, he discusses two questions that came up in a mealtime conversation during a visit to the Abbey of Monte Cassino.

Before we jump into his answers to the two questions in his letter, we must first bring up the Law on Non-contradiction, which states that a thing cannot be at once true and untrue. Sounds sensible. Aristotle in his Metaphysics states definitively that "contradictory propositions are not true simultaneously." He was building on Plato and Socrates and others.

The two questions that Damian tackles are these:

1. Can God restore a woman's virginity?
2. Can God undo history?

Damian maintains the view of God's omnipotence that says he can restore virginity. Virginity is a good thing, and so regaining it is a good thing; God will do something if it is a good thing. Therefore, God can and would do it, if He felt the situation warranted it. Restoring virginity would require two things: restoring the merit of virginity and restoring the physical change that loss of virginity causes (restoring the "integrity of the flesh"). The first is accomplished by returning to God's Grace, the second a simple matter of God restoring a person's flesh to an earlier condition.

Does this, then, imply that Damian believes that God can undo history? Not quite. In the case of restoring virginity, Damian states that God can do so as a miracle in the present time. He is not undoing an event that took place; He is changing a person's current state back to an original state.

Then what about history?

Damian, after a long and complicated discussion of the law of non-contradiction (and criticism of his peers for not understanding the subtleties of the question), explains that God cannot turn what has been done into something that has not been done. He denies, however, that this is an instance of a lack of omnipotence. Damian argues that God's omnipotence is His ability to bring about what is good. Creating a contradiction by changing what has been done to something that has not been done would be creating a contradiction, and therefore would be a bad thing. It would be turning something into nothing, and God creates things out of nothing, He will not create nothing out of something.

Okay, fine, but what about evil things? Wouldn't it be good for God to undo evil actions? Damian gets a little vague about this, and tells his audience not to worry about evil things. Evil things don't have the same kind of existence/value as good things, and so to erase them does not create a contradiction in the same way as erasing from the historical record a good thing.

Well, who am I to argue?

*In Canto XXI of the Paradiso, in the Seventh Heaven, a bright soul comes to speak to Dante and identifies himself as Peter Damian. The subject of corrupt popes comes up (surprise!).

Doctor Illuminatus

A brilliant scholar and fervent theologian/philosopher did such a good job at achieving his aims that the Church realized they had to suppress his work!

Ramon Llull was born in Majorca in the 1230s and probably was a courtier at the court of King James II of Aragon. He had a vision at the age of 30; while about to write a love letter, he turned and saw Christ on a cross hanging in the air. This image appeared to him five times, inspiring him to the religious life with very specific goals, one of which was to convert the Muslims to Christianity.

He did not intend simply to travel eastward and preach to the Muslim world; he had a more reasoned plan than that. He would counter their religion with logical and philosophical arguments that were so clear as to compel them to abandon their faith for his. His first task was to counter their great scholar, Averroes, and his first step was showing that theology and philosophy could be reconciled.

The Arab world had found comfort in separating the two, explaining that what was true in philosophy could be false in theology. Averroes himself had relied on this distinction to avoid persecution for his heretical idea about the non-existence of a unique soul that survives death. Llull decided to prove the Arab world wrong by reconciling philosophy and theology, raising the Christian West to an intellectually superior status that the East would have to fall in line with. He allied the natural and there supernatural, arguing that divine truths needed to be approached with reason guided by faith. Likewise, faith needs reason, lest it be misguided by personal desires or emotions. Llull had created a machine, the Ars Magna ["Great Art"], which would affirm the truth of propositions by lining up geometrically shaped pieces when levers and cranks were used. The machine was a three-dimensional representation of his "Llullian Circle" that could demonstrate all the possible truths of his system.

Llull's followers called themselves Llullists and spread the glory of his writings.* He met John Duns Scotus in 1297, who gave him his nickname of "Doctor Illuminatus" for the illumination he brought to the faith. His followers gained such influence in Spain that they were able to endow chairs at the Universities of Barcelona and Valencia.

Lullian Circle [source]

We know that he was stoned to death by the Muslim inhabitants of the town of Bougie on a mission to North Africa. Documents by Ramon Llull exist that can be dated to December 1315, but he was probably dead shortly after.

Despite his fame and religious zeal during his lifetime, and his martyrdom, he has never been considered for canonization by the Roman Catholic Church. The Church realized that his ideas were too radical. Sixty years after Llull's death, Pope Gregory XI (1327 - 1378) condemned his work, as did Pope Paul IV (1476 - 1559) a century after Gregory. Linking the natural and supernatural together was not going to work for the Church as a whole, despite the efforts of the "Illuminated Doctor." There were too many things that relied on faith for the Church to insist that, without reason, they would not pertain.

Centuries after Llull's death, some of his other writings were discovered that made his name prominent in the field of "election theory," but we'll save that for another time.

*He is considered to be the first major writer in the Catalan language.

Duns Scotus

I shocked myself the other day when I mentioned Duns Scotus in the post on St. Ivo and found that I had nothing in this blog to which to link! In 300+ posts I had somehow passed over Duns Scotus (c.1266-8 November 1308).

His contemporaries refer to him as Johannes Duns, and since there was a practice of using the Christian name plus place of origin, it is assumed that he came from Duns in Scotland (although a very late notation on a copy of his "final exam" on the Sentences of Peter Lombard claims he was from Ireland). We know that he was accepted into the Franciscans on 17 March 1291. Since the earliest age at which he could be accepted into the Order was 25, and since we assume he was accepted as soon as his age allowed, we surmise that his year of birth was 1265 or 1266. That encompasses most of what we "know" of the personal life of the figure who was called Doctor subtilis [Latin: Subtle doctor] due to his penetrating philosophical and theological insights.

He got into some trouble in June 1303 while lecturing at the University of Paris. King Philip IV "the Fair" of France (previously mentioned here) was taxing church property. Understandably, he was being opposed by Pope Boniface VIII. Scotus sided with the pope and was expelled from France with about 80 other friars. They were back about a year later.

Although he never wrote a giant compendium of all his thought the way others like Thomas Aquinas did, he is known for numerous commentaries in which he untangled many of the theological controversies of the day. Hence the title "Subtle doctor." His argument for the existence of God "is rightly regarded as one of the most outstanding contributions ever made to natural theology." [source] It has numerous details, but boils down to:

(1) No effect can produce itself.
(2) No effect can be produced by just nothing at all.
(3) A circle of causes is impossible.
(4) Therefore, an effect must be produced by something else. (from 1, 2, and 3)
(5) There is no infinite regress in an essentially ordered series of causes.
(6) It is not possible for there to be an accidentally ordered series of causes unless there is an essentially ordered series.
(7) Therefore, there is a first agent. (from 4, 5, and 6)

Both (5) and (6) have several sub-arguments, and after (7) he moves on to further details. His underlying assumption that makes much of his thought work is that God is infinite.

He also championed the doctrine of the Immaculate Conception of Mary, quoted in 1854 by Pope Pius IX in his declaration of that dogma.

Pope John XXIII (1881-1963) recommended Scotus' writings to theology students. In 1993, Pope John Paul II (1920-2005) beatified him.

There was a movie made about him in Italy in 2011, available on Amazon.

Nominalism vs Realism

Realism [link]

At the foundation of philosophy is a question: what defines reality? There are several questions that are connected to this. Let us start with: when we say that a lot of different animals are all dogs, to what quality are we referring that makes the Dachsund and the Great Dane both dogs? Is there an essential quality of "dog-ness"? Some universal concept that is inclusive of all dogs, despite the particular differences between breeds?

There it is: universals and particulars.

Realism says that both universals and particulars exist. That is, we recognize that different dogs/houses/trees are those things because, although they have different particulars, there is a universal essence of dogs/houses/trees that exists. Plato and Aristotle were Realists.

Nominalism says that the world is made only of particulars. Things we see are put into categories by our thought processes and our language, not by the existence of some abstract universal. William of Ockham and Jean Buridan were Nominalists.

In the two diagrams shown, we see that in Realism, although John and David have different Particulars, they are defined by their Universal quality as human beings. Nominalism, however, shows John and David only defined by their Particulars. The category of Humanity is created by us. There is no abstract "Humanity" essence that exists independent of John and David.

Nominalism [link]

Getting at the truth produced some fascinating thought experiments. One—The Puzzle of Theseus' Ship—was posed by Plutarch (46-120 CE). The ship of Theseus was preserved in Athens for several generations. As pieces of it decayed, they were replaced with new wood, so that the ship would stay intact. If a thing is based on its particulars, then with the particulars of this ship having changed over the years, is it still Theseus' ship? If there is some universal of Theseus' ship (as Realism says) then it is still his ship. If there are only particulars (as Nominalism says) then it isn't.

British philosopher Thomas Hobbes (1588-1679) took this a step further: if all the removed pieces were assembled into a complete ship, then which is Theseus' ship? Are they both Theseus' ship? He concludes that this would be absurd.

Even the early scholars understood that there were problems with these concepts, and struggled to reconcile the issues. Still, they did their best to understand how reality worked, and how that would help them to understand everything else.

...such as whether we have individual souls. That discussion will take us back to Averroes tomorrow.

The Commentator

Statue commemorating Averroes in Córdoba

Averroes (1126-1198) was born in Córdoba into a family of distinguished jurists and scholars at a time when Islamic culture was flourishing in Spain. He probably would have spent his life as a judge if not for his mentor and friend, the physician Abu Bakr ibn Tufayl, who told him that he should write commentaries on the works of Aristotle. The problem seen by ibn Tufayl was that Aristotle was too obscure either because of the ambiguity of his own writing or the shortcomings of his translators.

Averroes, whose real name was ʾAbū al-Walīd Muḥammad bin ʾAḥmad bin Rušd, embraced the task so thoroughly that, to the West, he became known as "The Commentator." His scholarship was embraced across cultures: Jacob Anatoli translated Averroes' Commentaries into Hebrew. Anatoli's colleague and friend Michael Scot translated some directly into Latin.

He analyzed and promoted most of Aristotle (and Plato's Republic) to the known world, as well as writing dozens of books of his own. So far as we know, he did not have access to original texts—there is no evidence that he knew Greek—and so his commentaries are based on Arabic translations of Aristotle.

Unfortunately for him, his rationalist views often got him into trouble when they came up against Islamic theology (which he had studied extensively). He was, in fact, banished by a caliph to whom he had been the personal physician, because some side remarks in Averroes' writing (such as "that Venus is one of the gods") struck the caliph as blasphemous. Fortunately, Averroes was allowed to return home prior to his death.

One of his most radical ideas, based on Aristotle, was that there were multiple intellects, but only one shared soul for all of mankind. To explain that raises more questions, however, unless first we look at a debate I have been putting off for months. Tomorrow, therefore, we will (finally) discuss Nominalism vs. Realism.

Defeating Eternity

How long has the universe existed? Has it been around forever? Did it have a beginning? Could it have a beginning? These questions troubled the ancients.

Aristotle in his Physics tried to answer this through reason. Everything that comes into being does so from something that already exists; matter is made from matter, after all. The matter of the universe would have to come into being from some underlying matter; it couldn't come from nothing. For the matter of the universe to come into being, some matter must have existed before it. This statement is ridiculously self-contradictory, and therefore could not be taken seriously. The universe must have always existed.

Others supported Aristotle. Critolaus (c.200-c.118 BCE) couldn't believe that human beings would ever stop simply procreating into eternity. In the Early Medieval Period, Proclus (412-485) produced De Æternitate Mundi (On the Eternity of the World) with 18 proofs.

This belief was about to collide headlong with Christianity, however. The Bible makes it clear that there was a moment of Creation. That being the case, the universe cannot have been eternal.

John Philoponus (490-570) was a prolific and controversial writer who realized that Aristotle needed to be questioned on some things. Although he would be condemned after his death as heretical for interpreting the Trinity as three gods instead of one God, he was known in his lifetime for defending the Biblical necessity of a universe with a starting point. He wrote "Against Proclus" in which he challenged every one of Proclus' arguments. The basis for his argument is simple, and referred to now as the Traversal of the Infinite. If the existence of something relies on the existence of something else prior to it, then you need to account for the existence of the prior thing. That prior thing would rely on the existence of something before that, and so on. You have to have an infinite series of assumptions that something existed before the thing that came afterward, and never actually explain where any of the substances came from. The world could not possibly be infinite, and must have been created by a divine being.

William of Ockham

The goal of Daily Medieval is to present a sampling of the infinite array of information about the Middle Ages in small, digestible amounts. It offers a taste of the thousand years of people, events, and ideas that don't get covered in the streamlined history books of standard academic courses. To that end, it tries to avoid those things that people "already know" and focus on the lesser-known lights that shone at the foundation of modern civilization. Sometimes, however, the obscure overlaps the well-known, and I find myself "forced" to write about something or someone that I worry is known well enough that the daily entry won't give the reader anything "new." My goal then becomes to broaden the reader's knowledge in unexpected ways.

Which brings us to William of Ockham. I would be surprised if readers of Daily Medieval had not heard of Occam's (or Ockham's) Razor, a guiding principle that says one should not make more assumptions than absolutely necessary to try to explain something.

William of Ockham (c.1285-1349) was responsible for so much more, however. Believed to have been born in Ockham in Surrey, England, he wrote about metaphysics, logic, theology, politics, and more. All this writing, however, happened when he left Oxford University in 1320 without a degree in theology. The prevailing theory for this unexpected departure is that he would not acquiesce to changing his commentary on the Sentences of Peter Lombard, a common part of the final examination for university students.

The basis for the theory is how the situation blew up years later. Ockham was summoned to Avignon to appear before Pope John XXII and a committee that would examine his writings. The committee, chaired by John Luttrell (an ex-chancellor of Oxford) found 51 heresies among William's commentary on the Sentences. It is believed that William escaped punishment by appealing to the Holy Roman Emperor (at the time, Louis IV), who was not always on good terms with the pope, saying to him "You defend me with the sword and I will defend you with the pen." In effect, he placed at the disposal of the Emperor his intellectual gifts, which (if this story is true) must have been known to be considerable for this ploy to work.

How did William earn his intellectual reputation? Between leaving Oxford in 1320 and arriving in Avignon in 1324, he spent three years in a Franciscan monastery, writing prolifically. One of the topics he put his mind to was whether priests should be allowed to own property. Franciscans believed priests should live a life of poverty. This put them into conflict with Pope John XXII, so the summons to Avignon and condemnation may have had more to do with that question than his Oxford writings.

Besides challenging the Church's ideas about material wealth, he was also challenging the ideas of people like Thomas Aquinas that reason was sufficient to determine everything we needed to know about the world.

But that's a story for another day.

Buridan's Ass

Buridan's Ass is the name given to a paradox: that a hungry and thirsty ass placed exactly in the middle between water and hay will be unable to choose because neither choice is preferable or closer; he will therefore die of thirst and hunger. The paradox is named for Jean Buridan (c.1300-c.1361), who studied and taught at the University of Paris. He had a reputation for being a bright and charismatic figure who had a way with the ladies, but that last part might have been spread by his detractors.

But Buridan, who wrote several works including answers to puzzles such as the liar paradox, never discussed the dilemma of the ass; he might have, because it had been around for hundreds of years.

Aristotle mocked the paradox in his De Caelo (On the Heavens). There was an idea circulating that one could explain the unmoving nature of the Earth simply because it was round and centered among all that existed, and therefore all forces acted upon it equally, maintaining an equilibrium. Aristotle mocked this idea by saying it was as ridiculous as if to say that "a man, being just as hungry as thirsty, and placed in between food and drink, must necessarily remain where he is and starve to death." Other early philosophers commented in this dilemma as well.

Why did it get ascribed to Buridan? In his works, he does consider that a rational choice could not be made by a rational person between two equally good options:

Should two courses be judged equal, then the will cannot break the deadlock, all it can do is to suspend judgement until the circumstances change, and the right course of action is clear.

This was just a "thought experiment" for him, however. He did not believe this would in fact lead to total inaction: he believed in a moral determinism that would lead one to a choice, even though that choice or preference might come through an unknowable thought process. Later writers mocked him by laying the burden of the ass paradox on him.

Buridan and Aristotle would cross paths on another issue, however: when a thrown object leaves the hand of the thrower, what keeps it moving? Aristotle had a theory that was clung to by many for centuries. Buridan had a different idea, one that anticipated Newton by about 300 years.

But that's a story for another day.