Does a reference to Descartes go right over your head? Use this cheat sheet to better understand the big ideas of some of history’s greatest thinkers.
Plato (428/427–348/347 B.C.)Best-known work: The Republic.
“The only real ill-doing is the deprivation of knowledge.”
Big ideas: Theory of Forms; platonic relationship.
- Everything on earth, whether an object (such as a car) or an idea (such as justice), is actually an imperfect copy of an ideal and permanent “form” that exists somewhere, beyond our universe. This is known as the Theory of Forms. The place where all these ideal forms exist is guided by a heavenly force that Plato believed should influence our behavior. (This notion shaped Christianity.) The ideal that was the most important to Plato was moral goodness, which he called “the good.” He believed that we should spend our lives trying to attain absolute goodness, even if we always fall short, because it is the path to happiness.
- Plato believed that the ideal version of love is a meeting of the minds and doesn’t entail a physical aspect―hence the term “platonic relationship.”
Aristotle (384–322 B.C.)Best-known work: Nicomachean Ethics (supposedly named after Aristotle’s son, Nicomachus).
“Anything that we have to learn to do, we learn by the actual doing of it.”
Big ideas: Deductive reasoning; golden mean; catharsis.
- When a person truly understands a topic, she can create a deductive argument―one that starts with a general concept and works toward a more specific one. Aristotle favored a type of deductive reasoning called syllogism (also a favorite of Sherlock Holmes), in which two premises are combined to reach a conclusion: All men are mortal. George Clooney is a man. Therefore George Clooney is mortal. (Although that might be hard to believe.)
- Life should be lived according to the “golden mean”―what Aristotle called the virtuous halfway point between two vices. For example, courage is the mean between cowardice and rashness.
- The emotional cleansing one experiences while watching a dramatic performance is what Aristotle termed “catharsis.” For example, you might have had a cathartic moment, with mixed feelings of hope and despair, when Kate Winslet delivered the line “I’ll never let you go, I promise” to a dying Leonardo DiCaprio in Titanic (if you weren’t busy looking at your watch).