The Laches is a dialogue concerned with the virtue of courage. Throughout the dialogue, two distinguished generals, Nicias and Laches take turns attempting to define the nature of courage while Socrates mediates and responds. By the end of the dialogue Socrates has defeated each of the arguments by the generals and proven to them that they cannot say what the nature of courage is because they do not know it. Despite the fact that Socrates, Nicias, and Laches are all conspicuous examples of courageous men, since not one of the men succeeds in defining courage, they have no real knowledge of it. In the end, Socrates instructs that the whole company go back to school again and that he will also do so himself.
The dialogue begins with a speech by Lysimachus to two of his friends, Nicias and Laches. Lysimachus and his friend Melesias want their sons to become honorable men and so have asked the advice of two generals about how they should educate their children and specifically what they think of the art of fighting in armor. To this question, Nicias responds that he believes the art of fighting in armor would be a good thing to learn for it would make the children want to learn other things in war. Laches replies that he believes the art of fighting in art to be a kind of knowledge without value. Laches argues that most of the men he has seen who are teachers of this art make fools of themselves on the battlefield. He relates a particularly long anecdote concerning a teacher named Stesilaus who was laughed at by all his companions in battle. Laches believes that fighting may be a form of knowledge; but since this knowledge does not make the masters of it better fighters, it is not worth knowing.
Lysimachus asks Socrates to break the tie between the two generals, but Socrates instead insists that they find out who is the expert among them and ask his advice. If they find none, then they will seek the advice of another teacher. Socrates then clarifies that he means to find the one out of them, not who is an expert in the art of fighting with armor, but that person who is an expert in the soul of youth since that is the end product of what they are discussing. Socrates asks that he, Nicias, and Laches give proof of which one of them is the most expert by showing the others who their teachers have been and who their students are. Socrates sarcastically states that he of course is unqualified because he has never been able to afford the teaching of the sophists and therefore recommends Nicias or Laches.
Nicias at this point accuses Socrates of carrying the conversation round and round with no end but to frustrate those with whom he is speaking. In response Laches claims that he dislikes conversation that is "out of tune." By this Laches means he dislikes it when a person's words fail to line up with their deeds. However, he states that he will listen to anything Socrates has to say on the subject of virtue because he knows that Socrates's deeds in battle are themselves so virtuous.
Socrates then shifts the conversation to focus on the nature of the thing that they are broadly attempting to discuss. Most generally, Socrates calls it this thing of virtue; but specifically, they are discussing only a part of virtue, which is courage. Laches defines a man of courage as one who does not run away from an enemy. Socrates explains that this definition does not cover all the cases of courage so that Laches must come up with a more general definition. Laches then defines courage as "an endurance of the soul." Socrates continues to press Laches to narrow his definition to a "wise endurance of the soul" and then proves to him that courage is actually closer to a foolish endurance of the soul.
At this point, Nicias attempts to define courage. Nicias defines courage as a kind of wisdom, or as "knowledge of the grounds for fear and hope." Laches criticizes Nicias, claiming that such a definition includes non-courageous men such as physicians or soothsayers. Socrates argues to Nicias that his definition fails to consider courageous animals such as the boar or the lion who have no knowledge. Nicias defends his definition against Socrates by drawing a distinction between courage, which is a form of wisdom, and fearlessness, which is what animals possess. Socrates attacks Nicias's position from a final angle by claiming that his definition that courage is knowledge of the grounds of fear and hope only deals with the future of courage and neglects the present and past. Therefore, Nicias extends his definition to include not only the knowledge of hope and fear—that is, knowledge of future good and evil things—but to include knowledge of all good and evil things, past, present and future. However, at this point Socrates notes that a man who had knowledge of all good and bad things at any time would embody all virtue and not merely a part of it. Being thus refuted, Nicias abandons his definition and not one of the men is able to get any closer to the nature of courage. Despite the fact that no one can state the nature of courage, Socrates is chosen as the teacher for the children of Lysimachus and Melesias. Jokingly, Socrates suggests that not only children—but all men—should go to school in order to learn the nature of courage.