Mandatory secrecy of the ballot protects voters from intimidation by removing proof.

Evidence

It is interesting to observe that political democracy itself depends on a game structure in which the communication of evidence is impossible. What is the secret ballot but a device to rob the voter of his power to sell his vote? It is not alone the secrecy, but the mandatory secrecy, that robs him of his power. He not only may vote in secret, but he must if the system is to work. He must be denied any means of proving which way he voted. And what he is robbed of is not just an asset that he might sell; he is stripped of his power to be intimidated. He is made impotent to meet the demands of blackmail. — Thomas C. Schelling, The Strategy of Conflict, 343

Categorization

• DEEPTHINKING: Reverses the usual framing of the secret ballot as protecting privacy into the sharper claim that forced ignorance is what breaks the extortion game - a genuinely paradigm-shifting reading of democratic procedure.
• XREF: Parallels the reader’s Mafia analysis: mandatory mutual ignorance (like the Godfather’s structured denial) as the mechanism that kills coercive bargaining. — connects to: Secret ballots protect voters by destroying evidence of their vote — Thomas C. Schelling, The Strategy of Conflict, 52; Secret ballot strips voters of power to prove their votes — Thomas C. Schelling, The Strategy of Conflict, 52

Related

• Secret ballots protect voters by destroying evidence of their vote (similarity 0.91)
• Secret ballot strips voters of power to prove their votes (similarity 0.88)