Socrates is brought to trial before the citizens of Athens, accused of not recognizing the gods that are recognized by the state, inventing new deities, and corrupting the youth of Athens. He apologizes that his defense speech will be plain and straightforward, as he hasn’t mastered the art of rhetoric employed by so many politicians. A defense speech in Greek is apologia, which gives this dialogue its title.

Socrates first denies previous complaints against him: that he gives physical explanations of divine matters and that he charges a fee for teaching rhetoric. He challenges anyone to testify that he has ever made any positive claims about the heavens or earth or that he has charged a fee for his teaching.

Socrates surmises that his reputation may have come from a prophecy by the Oracle at Delphi, which proclaimed he was the wisest of all men. Socrates has always admitted he knows nothing, so he was puzzled by this prophecy. To test it, he first examined the supposedly wise politicians of Athens and, by questioning them, discovered that they were full of hot air and in fact knew nothing. Next he questioned the poets, only to find that they were less able than others to explain their own works, leading Socrates to infer that it is not wisdom but divine inspiration that guides their writing. Then he questioned the craftsmen, who are very skillful but similar to the politicians in thinking they know all sorts of things they don’t know. Through all this questioning, Socrates earned many enemies but also concluded that he is wiser than everyone else because at least he knows that he knows nothing. He takes the Oracle as a command from Apollo to question men who think they are wise to show them that they are not.

Socrates calls forth Meletus, his chief accuser, and questions him about the charges he has laid. Socrates uses a fair bit of bullying and baiting and suggests Meletus is confused about the teaching of virtue and that he contradicts himself in accusing Socrates both of atheism and of inventing new gods.

Socrates persists in his practice, even though his life is in danger, because he feels he has a duty to Apollo. If he fears death, he would be presuming to know what happens after death. Since he cannot know, it is foolish to fear it, and he shouldn’t avoid acting justly because he’s afraid of dying. The people of Athens, not Socrates, should fear a death sentence, since they’ll be giving up Socrates’ valuable service. Socrates compares himself to a gadfly, who stings the lazy horse that is Athens, provoking it into action. Socrates has stayed away from politics at the warning of an inner voice that keeps him from heading into danger, a voice he calls a “supernatural sign.” A man like himself would never have lasted in politics, and so he would have been prevented from offering his services to Athens.

In closing, Socrates points out that the youth he has supposedly corrupted, including Plato, are upright men who still stand by him. Not even the parents or family of these people claim Socrates is a corrupting influence.