In early 1963, a single number characterized the difference in the positions of the United States and the Soviet Union on a comprehensive nuclear test ban. Nikita Khrushchev had proposed three on-site inspections each year. Washington was asking for seven. Other differences remained, including inspection procedures and treaty language. But the difference mattered: Seismology could not always distinguish an underground test from an earthquake, and inspections created both assurance and opportunities for espionage.Neither number had been delivered by a technical expert wielding a seismograph. Each represented a political judgment about how much residual uncertainty its government should accept. The negotiations The post Proving the Negative: Three Warnings from Arms Control for the Age of AI