“I Know That I Know Nothing”: Not in Plato. Cicero Said It
By It is the most famous sentence in the history of philosophy that nobody in that history wrote down.
"I know that I know nothing" does not appear in Plato’s Apology, or anywhere else in Plato, and Plato is the main source we have for what Socrates said. The scholar Gail Fine, in a 2008 paper on exactly this question, concluded that "it is better not to attribute it to him." What Socrates does say is narrower, and once you see the difference, it is more interesting than the slogan.
What Socrates actually says
The story is in the Apology, Plato’s account of Socrates’s defense at his trial. A friend of his, Chaerephon, had asked the oracle at Delphi whether anyone was wiser than Socrates, and the priestess said no one was. Socrates was baffled:
for I know that I have no wisdom, small or great.Plato, Apology 21b, trans. Benjamin Jowett
So he went looking for someone wiser, to prove the oracle wrong. He questioned a politician with a reputation for wisdom, and came away with this:
for he knows nothing, and thinks that he knows; I neither know nor think that I know.Plato, Apology 21d, trans. Benjamin Jowett
Read that carefully. Socrates is not claiming to know that he knows nothing. He is claiming not to think he knows what he does not. The politician’s problem is false confidence. Socrates’s advantage is that he does not have it.
That is a much more modest claim, and a much more usable one. It is not a riddle about knowledge. It is a description of a habit: when you do not know something, notice that you do not.
And Socrates does claim to know some things. Later in the same speech he says he does know that injustice and disobedience to a better is evil and dishonourable. A man who knew nothing could not say that.
Where the slogan comes from
The tidy paradox appears about three hundred years later, in Latin, in Cicero’s Academica. Cicero was arguing for philosophical skepticism, and he wanted Socrates on his side. In one passage his character Varro sums Socrates up like this:
He says that he knows nothing, except that one fact, that he is ignorant; and that he is superior to others in this particular, that they believe that they do know what they do not, while he knows this one thing alone, that he knows nothing.Cicero, Academica I.16, trans. C. D. Yonge
And later, in his own voice:
He excepted one thing only, asserting that he did know that he knew nothing; but he made no other exception.Cicero, Academica II.74, trans. C. D. Yonge
That is the slogan. But notice what it is: Cicero describing Socrates, three centuries on, in the middle of an argument for a position Socrates never held. It is a summary with an agenda, not a quotation.
A trap in the most common translation
There is one more reason the phrase seems to be in Plato. Benjamin Jowett’s translation of the Apology, the free one most people find online, opens with a long introduction by Jowett himself. In it he writes:
He knew nothing, and knew that he knew nothing: they knew little or nothing, and imagined that they knew all things.Benjamin Jowett, introduction to his translation of the Apology
That is Jowett, a Victorian scholar, paraphrasing. Search the free text for the phrase and you will find it, a few pages before Plato’s words begin. It is an easy mistake, and it has been made many times.
Why it matters for anyone practicing Stoicism
The Stoics admired Socrates more than any other philosopher, and what they took from him is the version in the Apology, not the slogan. Epictetus built a whole teaching on it: you cannot start learning what you think you already know. That is the politician’s problem, and it is most people’s.
So the useful version is not "I know nothing." It is "I don’t assume I know." The first is a paradox for a poster. The second is something you can actually do, today, the next time you feel certain.
This is on our list of misattributed Stoic quotes, along with another phrase credited to Socrates that was carved at Delphi before he was born. The Socrates line that does hold up, from the same speech, is "the unexamined life is not worth living."
Sources: Plato, Apology, trans. Benjamin Jowett, Project Gutenberg #1656; Cicero, Academica I.16 and II.74, trans. C. D. Yonge, Project Gutenberg #29247; Gail Fine, "Does Socrates Claim to Know that He Knows Nothing?", Oxford Studies in Ancient Philosophy 35 (2008).
Marcus turns this into a daily practice for iOS: a morning preparation, a daily reading, and a structured evening examination.
Explore the app →