Parmentier got the French to eat potatoes by making them worth stealing

By the late 18th century, the French public widely believed potatoes caused leprosy, associated them with poisonous nightshade relatives, and considered them food fit only for pigs — the crown had banned potato cultivation for human food for over twenty years.

None of that official validation moved ordinary French people, who had been taught for a generation that potatoes were dangerous and beneath them. In 1781, King Louis XVI granted Parmentier roughly 54 acres of land near Paris to plant potatoes. Rather than treating this royal endorsement as the persuasive tool, Parmentier posted armed guards around the field during the day — a visible, unmistakable signal that whatever was growing there was valuable enough to protect — and then withdrew the guards every night.

Guarded potatoes by day, left them unguarded at night, so locals stole and planted them, converting fear into desire through their own risk.

Guards signaled the potatoes were valuable without saying a word.

Withdrawing guards at night created a low-risk chance to steal.

Stealing and planting potatoes gave people personal investment in the crop.

Personal investment overrode the old belief that potatoes were dangerous.

When official endorsement fails, signal value through visible behavior—like guarding access—so people draw their own conclusions and invest personally.

The Paris Faculty of Medicine officially declared the potato safe to eat in 1772, and by the time France faced severe grain shortages in the years leading up to the 1789 Revolution, the potato — no longer feared but now something ordinary families were already cultivating in their own gardens because they'd effectively stolen it — became a critical famine food. Frederick the Great of Prussia used a similar reverse-psychology approach around the same period, and potato-based dishes bearing Parmentier's name (hachis Parmentier, pommes Parmentier) remain part of the French culinary canon today.