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.

Niccolò Machiavelli's The Prince is the famed treatise that he wrote as a kind of "manual for princes." Throughout the work, he advocates a kind of opportunism and "technical" strength for the princes who may read his work. Its overall aim is to present a picture—often using historical examples—of how one can keep his power as a prince. Although it is somewhat unfair to say that Machiavelli is wholly immoral, the treatise is marked by a kind of amoralism—in that its advice is not worried about virtue in the sense of "the good life" but instead hopes to show princes how to have virtù in the sense of "power." Hence, people often refer to self-centered power plays as being "machiavellian"—taking this word from the very name of Machiavelli!

In the 13th century, it became somewhat normal to try to write a comprehensive summary of the theology of the time, debating the questions of the day. Thus, figures like the Franciscan Alexander of Hales (1158-1245), Albert the Great (1200-1280), Henry of Ghent (1217-1293), and Thomas Aquinas (1225-1274) all wrote some form of summary of theological questions—though their forms do differ. 

The most famous of these throughout later history (for various reasons, some accidental, some related to the clarity and insightfulness of the text) was the Summa theologiae of Thomas Aquinas. This work is a massive outline of the science of theology, considering questions as varied as the nature of the Trinity to the natural law, to the various virtues, to the incarnation of Christ, to the sacraments. With the passage of time, it would become very influential in Catholic theology. (Although, it was not the only story in Catholic theology, for the Franciscans, Augustinians, and others all had their own schools of thought as well. Still, Thomas was the the thinker who won ecclesiastical approval most vociferously.)

The great Dutch humanist Desiderius Erasmus is perhaps most well known for his The Praise of Folly, a satire of the somewhat superstitious practices of Catholics in his day as well as the practices of scholars in that time. He also took part in a lengthy disputation with Martin Luther regarding the freedom of the human will in light of human sin. He also was extensively involved in working with Greek and Latin editions of classical, patristic, and biblical texts. While Erasmus was a critic of aspects of the Christian world of his day, he remained a Catholic all of his life. He was frustrated with corruption and wished to reform the Catholic church without the kind of radical measures undertaken by Luther. He was a friend of Sir Thomas More.

For some questions in the humanities, you just need to apply your general knowledge to help eliminate people. The Summulae Logicales of Peter of Spain were very important for many centuries—even though it is not completely clear just who the author, in fact, was! In any case, you may not know of Peter, but you should know that Kant is an 18th / 19th century figure, that Seneca is a Roman of the first century AD, and that Aristotle is a Greek from the fourth century BC. This leaves you with two options. Now, Aquinas is not known for writing texts in logic (although there are some logic texts falsely attributed to him, and he did write commentaries on several of Aristotle's logical works). Hence, if you at least know in general that Aquinas is not known for being a famed logician, you can guess that Peter of Spain is the correct answer—and you would be correct!

William of Ockham (1825-1347) is best known in the popular mind for the so-called "Ockham's razor," a common sense idea that we shouldn't just suppose that there are many kinds of beings in the world necessary for explaining our theories. He is, however, also known (for related reasons) as a "nominalist," that is, as someone who thinks that universal notions like "dog" and "tree" do not subsist in reality but only arise in the mind, which compares individual things that are maximally similar—hence, calling those individual things by a given universal name.

He also wrote the highly influential Summa logicae, which outlined a form of logic that was congenial to this outlook (as well as other aspects of his theory of mind and metaphysics). If you ever doubt that there was sophisticated philosophy in the middle ages, crack open Ockham's works, and you will see that he (along with many others) were quite agile minds indeed!