By Charles Mathewes, Ph.D., University of Virginia
Plato was an Athenian philosopher. He was a disciple of Socrates and the teacher of Aristotle. In his life, Plato wrote not just the dialogues we have, but several lectures that were also compiled into books and were available in the ancient world. what were Plato’s thoughts on evil?
In his early writings, Plato gave a very optimistic picture of what he thought to be evil. In his early dialogue, the Protagoras, he believed that evil was a consequence of ignorance; that no one goes against their well-formed judgment, and that such a well-formed judgment could never be truly evil.
Change in Plato’s Views and the Republic
But, as time went on for Plato, his views darkened. By the middle of his life, Plato understands ‘evil’ in a more profound, complicated, and troubling way, and his depiction of the differences between good and bad people has become far more radical.
This is probably seen best in his discussion of the dangers of the ‘irrational’, character of Thrasymachus in the Republic. Thrasymachus is a Sophist—someone who teaches people the arts of political rhetoric.
In the first book of the Republic, Thrasymachus and Socrates have a fierce debate on the nature of justice. Thrasymachus claims that justice is just the interest of the stronger. As it comes out in the conversation, this isn’t even a definition of justice; it’s kind of a use of words meant to bully others into submission.
What does it mean to say that justice is the interest of the stronger? That’s not a definition, but an attempt to refuse the point of giving a definition precisely because the point of that idea of what justice is just to use force where people would actually like to have understanding.
Thrasymachus

Thrasymachus debates Socrates just to get a submission from him, and not to get cognitive agreement. In fact, Thrasymachus’s name in Greek actually means ‘fierce or terrible fighter’. Machus is a warrior, and he’s presented in this first book as roaring, sweating, shaking, loud, and blustery. He blushes at times, he’s not fully in control of his body or his emotions, which, in fact, the emotions are really just an aspect of his body; his body is in control of him, but his body isn’t coherent, it’s a series of passions and desires.
What Thrasymachus wants most of all is just to get his own way, to intimidate other people. And, when he is unable to do so in a conversation, especially with Socrates, he withdraws into a kind of surly silence of his own for most of the rest of the dialogue.
Learn more about the inevitability of evil.
Thrasymachus Contradicts Plato’s Early Views on Evil
Thrasymachus represents, for Plato, a really crucial problem for social order and harmony: He can’t be engaged in an intellectually serious manner. He is more of a symptom of a world gone mad; a symptom that must be diagnosed and for which a cure must be found and prescribed.
Now, Considering the first idea Plato had of evil, that evil is in some sense ignorance, no amount of new information is going to help Thrasymachus. He’s not really interested in changing or any information. He doesn’t want to learn; he just wants to dominate others.
This is a transcript from the video series Why Evil Exists. Watch it now, Wondrium.
Evil and Unintelligibility

Here, then, in the Republic, Plato has deepened his sense of the connection between goodness and intelligibility. Goodness remains the properly intelligible thing to do, as in his younger view; but now unintelligibility of evil has become more profound and radical in the human character, especially in those characters who are not on the road to intelligibility.
Thrasymachus is not just incapacitated in his knowledge of good and evil; he’s incapacitated in his larger intellectual grip on the world as a whole. Indeed, he has no intellectual grip on the world; his response to reality, to the world, is more a matter of irritable appetitive reactions to not fully understood stimuli.
Thrasymachus, then, represents a terrifying challenge to Plato; and that it was people like Thrasymachus who, in a few years, would end up offering to kill, ordering Socrates to be killed.
The worry about Thrasymachus with Plato is not just that he’s silly or harmless; the worry is that we live in a world where Thrasymachuses also live, and the world that we live in is often one governed by people who are like Thrasymachus.
Learn more about the Greek philosophy of human evil and malice.
Dealing with an Irrational World
What should we do about that? That is, after the first book of the dialogue, the fundamental question of the rest of the Republic: How should we live in a world governed by people who are not really on the way to being intelligible creatures? That’s a terrifying question and Plato must ask two important questions here. First, how far can the wholly irrational—what Plato calls the alogon, the completely arational—be brought into the realm of logos, the realm of reason, of discourse; the realm of human intelligibility?
How far can Thrasymachus be brought into the conversation of the Republic, and what does his being brought into it look like? Second, if we can’t finally bring this alogon into the realm of logos, if we can’t finally bring the figure of Thrasymachus into the realm of intelligibility, how can we improve the social order, our world in general, so that there are fewer Thrasymachuses in the future?
Evil, here, is not so easily captured in descriptions of accident and ignorance; it seems more tenaciously part of our world, more difficult to correct, and requiring far more fundamental changes for us to be unsusceptible to its attractions than the mere delivery of more information to those caught in its clutches.
Common Questions about Plato’s Views on Evil
Thrasymachus was a sophist. In the Republic, he and Socrates have a fierce debate on the nature of justice.
Thrasymachus represents, for Plato, a really crucial problem for social order. He can’t be engaged in an intellectually serious manner. He’s not really interested in any information. He doesn’t want to learn; he just wants to dominate others. So his case is not of ignorance but unwillingness to learn.
Thrasymachus has no intellectual grip on the world. His response to reality or to the world is more a matter of irritable appetitive reactions to not fully understood stimuli.