Definition
Ostracism was a democratic safeguard in ancient Athens in which citizens scratched the name of a politician who might become a tyrant onto a broken piece of pottery (an ostracon), and the person named most often was sent out of the city for 10 years.
Democracy Cast on Broken Pottery
When you vote at school or work, you use a paper ballot. Ancient Athenians used something they could find lying around everywhere: broken pieces of pottery. The Greek word for a pottery shard is "ostracon," which is where the English word "ostracism" comes from.
Athens had only just broken away from rule by a single king or tyrant and started a democracy where all citizens took part. But there was always a risk. A hero with too much power and popularity could take control and start acting like a king.
So each year the Assembly first decided whether to hold an ostracism vote that year. If the answer was yes, citizens gathered in the marketplace about two months later and scratched the name of the person most likely to become a tyrant onto a shard. The most widely accepted account says that if the total vote passed 6,000, the person named most often had to leave the city. Another ancient account says one person had to receive 6,000 votes, so historians still disagree.
Not a Prison Sentence but a "Vaccine for Democracy"
In soccer, a red card punishes a player for a rough foul. Ostracism was different. It was not a punishment for a crime. It was more of a preventive measure, used when someone was so talented or popular that he might overwhelm the other citizens.
An ostracized man did not lose his property, and his family could stay in Athens. Income from the property he left behind still reached him. When the 10 years were up, he could return with no penalty and enjoy his full rights as a citizen again.
In short, it was a safety valve. It kept any one person from growing so huge that he upset the balance of a society of equals, by letting the city cool down and catch its breath.
A Closer Look: A Political Weapon Against Rivals
The system was meant to prevent tyranny, but it produced a dangerous side effect fairly early on. Politicians began using it not to protect the state, but as a tool to sway and manipulate voters so they could legally push out their own rivals.
Excavated shards show this clearly. About 190 shards bearing the name of Themistocles were found together in a single well. Many scholars read this as a sign that the names were written in advance, ready to be handed out to voters.
Even Themistocles, the great general who led Athens to victory in the Persian Wars, was driven out by his enemies' smears. Around 417 BC, rivals Alcibiades and Nicias teamed up and pooled their votes, and Hyperbolus, who had pushed for the vote, was ostracized instead. This was the most blatant abuse yet, and after it ostracism was never used again.
Common misconceptions
Ostracism was a trial that punished violent criminals or traitors who broke the law.
It was not a punishment for crime. It was a preventive political tool that let citizens vote to set aside a powerful politician who might become a tyrant. There was no confiscation of property or loss of status, and after 10 years the person could return with honor.
Where you meet it
Themistocles, the hero who saved Athens at the Battle of Salamis, was ostracized after rivals who feared his growing power stirred up the voters.
Aristides, a politician famous for his honesty, was ostracized too. According to a famous story, one citizen voted against him because he was "tired of hearing him called 'the Just.'"
In one sentence
Ostracism was ancient Athens' way of defending its democracy: citizens wrote a powerful person's name on a broken piece of pottery to send him away for 10 years and head off a would-be tyrant.