1. “The unexamined life is not worth living” – Socrates (470-399 BCE)

Socrates’ [wiki] belief that we must reflect upon the life we live was partly inspired by the famous phrase inscribed at the shrine of the oracle at Delphi, “Know thyself.” The key to finding value in the prophecies of the oracle was self-knowledge, not a decoder ring.

Socrates felt so passionately about the value of self-examination that he closely examined not only his own beliefs and values but those of others as well. More precisely, through his relentless questioning, he forced people to examine their own beliefs. He saw the citizens of his beloved Athens sleepwalking through life, living only for money, power, and fame, so he became famous trying to help them.

2. “Entities should not be multiplied unnecessarily” – William of Ockham (1285 - 1349?)

Commonly known as Ockham’s razor, the idea here is that in judging among competing philosophical or scientific theories, all other things being equal, we should prefer the simplest theory. Scientists currently speak of four forces in the universe: gravity, the electromagnetic force, the strong nuclear force, and the weak nuclear force. Ockham [wiki] would certainly nod approvingly at the ongoing attempt to formulate a grand unified theory, a single force that encompasses all four.

The ultimate irony of Ockham’s razor may be that some have used it to prove God is unnecessary to the explanation of the universe, an idea Ockham the Franciscan priest would reject.

3. “The life of man [is] solitary, poor, nasty, brutish, and short.” – Thomas Hobbes (1588 – 1679)

Referring to the original state of nature, a hypothetical past before civilization, Hobbes [wiki] saw no reason to be nostalgic.

Whereas Rousseau said, “Man is born free, and he is everywhere in chains,” Hobbes believed we find ourselves living a savage, impossible life without education and the protection of the state. Human nature is bad: we’ll prey on one another in the most vicious ways. No doubt the state imposes on our liberty in an overwhelming way. Yet Hobbes’ claim was that these very chains were absolutely crucial in protecting us from one another.

4. “I think therefore I am” – René Descartes (1596 – 1650)

Descartes [wiki] began his philosophy by doubting everything in order to figure out what he could know with absolute certainty. Although he could be wrong about what he was thinking, that he was thinking was undeniable. Upon the recognition that “I think,” Descartes concluded that “I am.”

On the heels of believing in himself, Descartes asked, What am I? His answer: a thinking thing (res cogitans) as opposed to a physical thing extended in three-dimensional space (res extensa). So, based on this line, Descartes knew he existed, though he wasn’t sure if he had a body. It’s a philosophical cliff-hanger; you’ll have to read Meditations to find out how it ends.

5. “To be is to be perceived (Esse est percipi).” Or, “If a tree falls in the forest and no one is there to hear it, does it make a sound?” – Bishop George Berkeley (1685 – 1753)

As an idealist, Berkeley [wiki] believed that nothing is real but minds and their ideas. Ideas do not exist independently of minds. Through a complicated and flawed line of reasoning he concluded that “to be is to be perceived.” Something exists only if someone has the idea of it.

Though he never put the question in the exact words of the famous quotation, Berkeley would say that if a tree fell in the forest and there was no one (not even a squirrel) there to hear it, not only would it not make a sound, but there would be no tree.

The good news is, according to Berkeley, that the mind of God always perceives everything. So the tree will always make a sound, and there’s no need to worry about blipping out of existence if you fall asleep in a room by yourself.

6. “We live in the best of all possible worlds.” – Gottfried Wilhelm Leibniz (1646 – 1716)

Voltaire’s famous novel Candide satirizes this optimistic view. And looking around you right now you may wonder how anyone could actually believe it. But Leibniz [wiki] believed that before creation God contemplated every possible way the universe could be and chose to create the one in which we live because it’s the best.

The principle of sufficient reason holds that for everything, there must be sufficient reason why it exists. And according to Leibniz the only sufficient reason for the world we live in is that God created it as the best possible universe. God could have created a universe in which no one ever did wrong, in which there was no human evil, but that would require humans to be deprived of the gift of free wills and thus would not be the best possible world.

7. “The owl of Minerva spreads its wings only with the falling of the dusk.” G.W.F. Hegel (1770 – 1831)

Similar to “vision is 20/20 in hindsight,” Hegel’s [wiki] poetic insight says that philosophers are impotent. Only after the end of an age can philosophers realize what it was about. And by then it’s too late to change things. It wasn’t until the time of Immanuel Kant (1724 - 1804) that the true nature of the Enlightenment was understood, and Kant did nothing to change the Enlightenment; he just consciously perpetuated it.

Marx (1818 – 1883) found Hegel’s apt description to be indicative of the problem with philosophy and responded, “the philosophers have only interpreted the world differently, what matters is to change it.”

8. “Who is also aware of the tremendous risk involved in faith – when he nevertheless makes the leap of faith – this [is] subjectivity … at its height.” – Søren Kierkegaard (1813 – 1855)

In a memorable scene from Indiana Jones and the Last Crusade, Indy deduced that the final step across his treacherous path was a leap of faith. And so it is in Kierkegaard’s [wiki] theory of stages of life.

The final stage, the religious stage, requires passionate, subjective belief rather than objective proof, in the paradoxical and the absurd. So, what’s the absurd? That which Christianity asks us to accept as true, that God became man born of a virgin, suffered, died and was resurrected.

Abraham was the ultimate “knight of faith” according to Kierkegaard. Without doubt there is no faith, and so in a state of “fear and trembling” Abraham was willing to break the universal moral law against murder by agreeing to kill his own son, Isaac. God rewarded Abraham’s faith by providing a ram in place of Isaac for the sacrifice. Faith has its rewards, but it isn’t rational. It’s beyond reason. As Blaise Pascal said, “The heart has its reason which reason does not know.”

9. “God is dead.” – Friedrich Nietzsche (1844 – 1900)

Well, you might not hear this one in a graduation speech, but you’ll probably hear it in college. Actually, Nietzsche [wiki] never issued this famous proclamation in his own voice but rather put the words in the mouth of a character he called the madman and later in the mouth of another character, Zarathustra.

Nevertheless, Nietzsche endorsed the words. “God is dead” is often mistaken as a statement of atheism. It is not, though Nietzsche himself was an atheist. “Dead” is metaphorical in this context, meaning belief in the God of Christianity is worn out, past its prime, and on the decline. God is lost as the center of life and the source of values. Nietzsche’s madman noted that himself came too soon. No doubt Nietzsche, too, thought he was ahead of his time in heralding this news.

10. “There is but one truly serious philosophical problem, and that is suicide.” – Albert Camus (1913 – 1960)

Camus’ [wiki] solution to the philosophical problem was to recognize and embrace life’s absurdity. Suicide, though, remains an option if the absurdity becomes too much. Indeed Camus’ own death in a car crash was ambiguous. Was it an accident or suicide?

For Camus, the absurd hero is Sisyphus, a man from Greek mythology who is condemned by the gods for eternity to roll up a stone up a hill only to have it fall back again as it reaches the top. For Camus, Sisyphus typified all human beings: we must find a meaning in a world that is unresponsive or even hostile to us. Sisyphus, Camus believed, affirms life, choosing to go back down the hill and push the rock again each time. Camus wrote: “The struggle itself toward the heights is enough to fill a man’s heart. One must imagine Sisyphus happy.”

11. “One cannot step twice in the same river.” – Heraclitus (ca. 540 – ca. 480 BCE)

Heraclitus definitely isn’t alone here. His message was that reality is constantly changing it’s an ongoing process rather than a fixed and stable product. Buddhism shares a similar metaphysical view with the idea of annica, the claim that all reality is fleeting and impermanent.

In modern times Henri Bergson (1859 – 1941) described time as a process that is experienced. An hour waiting in line is different from an hour at play. Today contemporary physics lends credence to process philosophy with the realization that even apparently stable objects, like marble statues, are actually buzzing bunches of electrons and other subatomic particles deep down.

Bonus: Fake Your Way Through a Conversation (with Correct Pronunciation!)

If you fumble with a philosopher’s name, nothing you say afterward will sound credible. So, learn to pronounce these names correctly, then start worrying about their ideas.

(George) Berkeley is properly pronounced like Charles Barkley (bark-lee). This name is commonly mispronounced “burk-lee” like Berkeley, California, which, ironically, is named after George Berkeley.

(Friedrich) Nietzsche is commonly mispronounced as “nee-chee.” The correct pronunciation is “nee-ch-ya” and rhymes with “pleased ta meetchya.” “Pleased ta meetchya, Neechya.” Say it!

Lao-tzu (born ca. 604 BCE) is spelled several different ways in English transliteration from the Chinese. But no matter how you spell it, the proper way to pronounce it is “lau” (sounds like “ouch”)-“dsuh”. The stress goes on the first syllable.

(Charles Sanders) Pierce Peirce (1839 – 1914) is commonly mispronounced as “peer-s.” The correct pronunciation is “purse,” which is somewhat funny because Pierce Peirce rarely had a penny in his purse. Oddly, Pierce Peirce took his middle name, Sanders, as an anglicized form of Santiago, or “St. James,” in honor of a fellow pragmatist, William James (1842 – 1910), who helped him out financially.

(Ludwig) Wittgenstein (1889 – 1951) is a name that demands authentic German pronunciation, and there are plenty of ways to slaughter it. Here’s one that embodies all of them, “wit-jen-steen.” The correct pronunciation is “vit” (rhymes with bit)-“ghen” (rhymes with ken)-“shtine.” The first name is pronounced “lude-vig.” If you think it’s hard to pronounce his name, try reading his Tractatus.

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From mental_floss' book Condensed Knowledge: A deliciously Irreverent Guide to Feeling Smart Again, published in Neatorama with permission.

[Update 3/15/07: Original article written by William Irwin, associate professor of philosophy at King's College in Wilkes-Barre, PA.]

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