Thomas Aquinas, the preeminent medieval Catholic philosopher and theologian, is best known for the massive Summa Theologiœ, which in Latin means "a summation of theology." Aquinas sought to summarize Christian scriptures, classical philosophy like that of Aristotle, and Christian theology like that of Augustine. Thomas Aquinas was attempting to unify all previous thought in the Western tradition to make logical and rational arguments for Christian doctrine.

During the second half of the 13th century, there were several standard philosophical styles. One was the style of literal commentary, which was used for interpreting the texts of Aristotle and other accepted authorities. In addition, within theological circles, there was the development of the so-called "summae"—lengthier summaries of doctrine, sometimes quite systematic in nature.

These large texts, however, were made up of questions that were written in a style quite peculiar to the Middle Ages, namely that of "disputed questions." These texts would set forth a question, take options "pro" and "con" and then make a conclusion based upon both sides of the question. Sometimes, in shorter works like this, the author would only consider the options that were contrary to his own, helping the reader to understand some possible objections to the text. 

This style of disputation was used in many of the treatises that began to be written late in the 13th century and into the 14th. It remained a style that was used especially in Catholic thought for some time. It was, however, most vigorously used as a writing style during this period of the Middle Ages.

(It should be added that there were also short treatises written during this time. They are not, however, the most unique style of writing during the time period.)

The Middle Ages were a complex period of time—spanning many centuries and having many thinkers. There were some thinkers Peter Damian who had negative thoughts about theology, as well as Bernard of Clairvaux, who warred at length with the Peter Abelard, accusing the latter of heresy. Indeed, even the philosophically erudite Bonaventure of Bagnoregio had his reservations regarding the place of philosophy in the curriculum at the University of Paris.

However, many figures (indeed, including Bonaventure) supported the use of philosophy in teaching. Such figures include the "big names" as Augustine of Hippo, Thomas Aquinas, John Duns Scotus, and many, many others. Indeed, even in the monastery schools (that would be important for thinkers like Bernard), some philosophy was indisputably necessary for learning.

However, what was quite unique to the Middle Ages—whether in academic settings like Paris or in the humblest of monastic schools—was the overall structure of the disciplines. For a Medieval philosopher, philosophy was always a "stepping stone" to something else. Indeed, its most important role was to be an assistant to theological studies. Hence, it is most often known as the "handmaiden of theology." (Indeed, Peter Damian gave this name to it so as to insult it—as if to say, "It is only a handmaiden.) Philosophy studies were really just a gateway to medical, legal, and theological studies (whether academic theology or the biblical theology of the monasteries). Above all, though, if we wanted to characterize the outlook regarding philosophy during these centuries, the best phrase (at least among those provided here) would be, "Handmaiden of theology."

The notion of the "liberal arts" is notoriously slippery. In different ages, different things are said to be part of the liberal arts. As the curriculum of the medieval university solidified, however, the seven liberal arts took up a basic form that became normalized by the twelfth / thirteenth century. These were divided into the "trivium" and the "quadrivium"—or, the "three subjects" and the "four subjects." The trivium was devoted to topics needed for all other learning, so it focused on grammar, rhetoric, and logic. These introduced the quite young students to the tools needed for later studies. The quadrivium was made up of primarily mathematical courses, namely arithmetic, geometry, astronomy (like physics today), and music (a study of harmonies and proportions).

Working from the monastery of St. Peter at Jarrow, in Northeast England, the Venerable Bede composed his Ecclesiastical History of the English People in the early eighth century. Written in Latin, the work was the first large scale history of England and the English people. For centuries afterward, English historians relied on Bede to help craft their own works.

John Calvin was a French clergyman who was highly influential in the early Protestant Reformation, and who developed his own view of the church, government, and humanity while living in Geneva in Switzerland. Calvin's Institutes of the Christian Religion, with ruminations on man’s nature and the notion of free will, was hugely influential on philosophy inside and outside the Christian tradition.

Utopia, which not only described a perfect community and form of government, but gave its name to such a concept, was written by the Englishman Thomas More in 1516. At the time, More was an envoy to Flanders, and was considering the appropriate form of government. More's Utopia takes place on an island, which is democratic, largely fair to all of its citizens, and functions through reasoned debate.

Augustine of Hippo was a figure that straddled two eras, from the end of the Roman Empire into the Middle Ages. In fact, his book The City of God was written directly as a response to the sack of Rome in 410 CE. The book is Augustine's attempt to reconcile the destruction of the Holy City with God's continued plan for humanity, and it proved influential to the entirety of Western Christianity for the next one thousand years.

Niccolo Machiavelli's The Prince (1513) reflected his own experience in Borgia-controlled Florence, and due to its issues Machiavelli argued for rulers doing whatever they had to do to take power. This "realpolitik" viewpoint was so influential it became known as being "Machiavellian." Scholars still debate, however, whether Machiavelli was being serious or satirically criticizing politicians.

The Praise of Folly presents a satirical, enthusiastic description of the concept of "folly." Typical of Erasmus' other writings, the work shows off an extensive amount of knowledge of classical texts, a clever use of Latin, and a humorous approach. Erasmus, though, hated its immense popularity, as he viewed it more as a light piece meant to amuse his fellow humanists, such as Thomas More.