How did Plato’s military service influence his philosophy?

Plato probably did serve as a soldier, but almost nothing about that service is known, so any claim that war shaped his philosophy is an interpretation, not a documented fact. The only direct report is late and partly confused. Diogenes Laertius (III.8), writing more than five centuries after Plato’s death and citing the musician-philosopher Aristoxenus, says Plato served on three campaigns, at Tanagra, Corinth and Delium, and won a prize for valour at Delium. Scholars doubt this, because Delium was fought in 424 BC, when Plato (born c. 428/427 BC) was about three years old. The report may have been muddled with Socrates, who really did fight at Delium and Potidaea (Plato, Symposium 219e–221c; Apology 28e; Laches 181a–b). Plato’s own works never mention any military service of his. What can fairly be said is that an Athenian citizen of his class would very likely have been called up at some point during the Peloponnesian War (431–404 BC) or the Corinthian War (395–387/6 BC). Everything below that goes further than this is reading, and is labelled as such.

Plato’s Views on Courage and Wisdom

Courage is treated at length in two of Plato’s works. In the Laches, two Athenian generals, Laches and Nicias, try with Socrates to define it and fail: Laches proposes standing firm in the ranks, then endurance of the soul, and Nicias proposes knowledge of what is to be feared, and each definition is picked apart (Laches 190e–199e). In the Republic (429a–430c) courage is the quality of the soldier-class, defined as preserving, through pleasures and pains, a correct belief about what is and is not to be feared. See what Plato meant by courage for a fuller account, and why Plato would write the Laches.

So Plato does move from battlefield bravery to something more demanding, a settled understanding of what is truly worth fearing. Whether that move owes anything to his own experience of war is not something the texts tell us. A reader can reasonably suspect it did, since the Laches is set in a world of generals and veterans, but that is inference. Courage and wisdom are also tied together in the dialogues for reasons internal to the argument: Socrates repeatedly pushes the view that virtue is a kind of knowledge.

Link Between Military Bravery and Philosophical Understanding

The clearest first-hand military material in Plato is about Socrates, not Plato. In the Symposium (219e–221c) Alcibiades describes Socrates enduring cold and hardship at Potidaea and keeping his composure in the retreat from Delium, and in the Apology (28e) Socrates cites his service at Potidaea, Amphipolis and Delium as proof that he would hold his post when the god ordered him to philosophise. In the Laches (181a–b) Laches himself says that if every Athenian had conducted himself as Socrates did in that retreat, the city would have kept its head high and not suffered such a fall. In each case Plato uses soldiering as a measure of character, and compares the philosopher’s steadiness to a soldier’s. That is a literary and ethical link, and it does not tell us what Plato himself did in the field.

The Concept of Leadership in Plato’s Works

Leadership is central to Plato’s political writing, but its source in his life is better documented than the military material. The Seventh Letter (324b–326b), whose authenticity is debated, says that as a young man Plato expected to enter public life, was repelled first by the oligarchy of the Thirty in 404 BC, which included relatives of his, and then by the restored democracy’s execution of Socrates in 399 BC. It concludes that cities will not be well governed until philosophers rule or rulers become philosophers. That is also the central thesis of the Republic (473c–e).

The philosopher-king, however, is not a general. In the Republic the rulers are the wisest of the guardians, chosen after long education in mathematics and dialectic, and they are distinct from the auxiliaries, who are the soldiers (414b). For more on that figure, see the role of the philosopher-king.

Exploration of Military Leadership and Philosophical Guidance

There is no evidence that Plato ever commanded troops, and the claim that he “led” men in battle has no source. What the Republic does contain is a detailed design for a military class: the auxiliaries are to be trained from childhood in gymnastics and music, to be gentle to their own people and fierce to enemies, like well-bred guard dogs (374e–376c), and the children of the guardians are to be taken to watch battles at a safe distance so that they learn the trade (467c–e). That shows Plato had thought carefully about how soldiers should be formed. Whether he drew on his own service for this is unknowable, and the design equally reflects what an Athenian observer would have seen of Sparta and of his own city’s citizen militia.

Plato’s Critique of War and Aggression

Plato’s writing on war is more qualified than a simple condemnation. In the Republic (373d–e) war arises when a city grows luxurious and wants more land, so a city that wants only what it needs has no reason for it, but the ideal city still keeps an army because it must defend itself. The Republic (466e–471c) also sets rules of conduct for war between Greeks, for example against enslaving fellow Greeks and ravaging their land, and treats fighting between Greek cities as a kind of civil strife (stasis) to be conducted with the aim of reconciliation.

The Laws goes further. In Book I (625e-631a) a Cretan speaker assumes that every city is by nature at war with every other, and the Athenian replies that a lawgiver should aim at peace and the whole of virtue, not courage alone, and that the worst war is civil war. Plato therefore does argue that war should serve peace, and that skill in war alone is a poor basis for a constitution. He does not argue that military force is never justified.

Examination of Military Violence in Plato’s Criticisms

Plato’s criticism of violence is tied to its effect on the soul and on the city. The Republic treats the worst political disorder, tyranny, as the result of unrestrained appetite in a ruler, and the Seventh Letter treats the violence of the Thirty as what turned him away from politics. Those are ethical and political judgements, and they draw on what Plato had seen of Athens in 404–399 BC, which can be documented from the Letter, whatever his experience as a soldier was. For modern readers, the safest summary is that war and its aftermath were the background of his whole adult life, and that his works keep returning to courage, civil conflict and the education of soldiers.

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Related Links

How did Plato receive education and mentorship?
The Military Service of Plato: A List of Influential Factors