This keeps cropping up in online debates:

“The paraphrased saying, though widely attributed to Plato’s Socrates in both ancient and modern times, actually occurs nowhere in Plato’s works in precisely the form “I know I know nothing.”  Wikipedia 

To give some context, Socrates that he is the wisest man in Athens by the Oracle at Delphi. Given that Wisdom is the possession of knowledge, Socrates is confused by this, and goes about finding out how wise other people are, what it is that they know.

And what he finds is that a lot of people THINK they know things that in fact they do not know,

He asks generals what courage is, and they while they say they know, when they explain themselves, it turns out that they can’t say:

• He asks politicians what justice is and finds the same,
• He asks philosophers what wisdom is and finds it to be the same.
• He asks poets what beauty is and finds the same,

Here is the critical passage from the Apology,

“I am wiser than this man; it is likely that neither of us knows anything really beautiful and good, but he thinks he knows (this) when he does not, whereas when I do not know (this), neither do I think I know (this); so I am likely to be wiser than he to this small extent, that I do not think I know what I do not know (this).” Apology 21d:

Socrates is not wiser than other people because he knows more things, and he does certainly know things. Much of Socrates’ dialogues are devoted to the these kind of questions questions, which is what he means by “knowing anything worthwhile”. The knowledge of the beautiful and the good, the nature of virtue.

• What is courage?
• What is wisdom?
• What is love?
• What is beauty?
• What is justice?

So what makes him wise is that he does NOT think he knows the beautiful and the good when he does NOT  know the beautiful and the good,

It is known as Socratic humility, self-knowledge, knowing the limits of your knowledge.

Contrast that with the common assumption here.

“What makes him wise is that he knows nothing at all.”

That would be very strange because elsewhere, he describes in detail how wisdom is knowledge of the beautiful and the good, which includes the limits of your knowledge of this.

Know thyself:

TLDR

• • Socrates does not claim that he knows nothing at all.
  • He admits he lacks knowledge of the most important things –
  • The beautiful and the good,
  • The nature of virtue, courage, wisdom, love, beauty, and justice.
  • Others claim to know these things when they do not,
  • Socrates owns up to not knowing these things when he does not know them.
  • What Socrates has is self-awareness, intellectual honesty, and humility.
  • In the Euthydemus, Socrates claims that wisdom is knowledge and that:
  • Knowledge is the only good and
  • Ignorance is the only evil