Mesmer and animal magnetism: what the 1784 commission actually tested

Franz Anton Mesmer (1734–1815) promoted animal magnetism: an invisible fluid whose redistribution, he said, explained illness and cure. Paris society took it up. Sceptics asked whether anything physical was flowing.

Key evidence

In 1784 Louis XVI appointed physicians and Academy of Sciences members (including Benjamin Franklin) to examine the practice as then demonstrated (notably by Deslon). An English printing of the commissioners’ report is on the Internet Archive.

They did not run a modern clinical trial. They asked whether a magnetic agent could be shown when patients did not know they were being “magnetised.” Effects clustered with expectation and imitation. The report’s famous triad is touch, imagination, and imitation, not a fluid.

A later historical note records that Mesmer had already floated a kind of comparative trial in 1780; the royal commission chose a different question (does the fluid exist?).

Braid later rejected the fluid story and renamed the procedure. See James Braid.

Limitations

“Mesmer was a fraud, therefore hypnosis is fake” does not follow. The commission falsified a fluid. It did not grade twentieth-century hypnotherapy RCTs.

What we don't know yet

How many of Mesmer’s “cures” were natural history, social contagion, or lasting change cannot be recovered from 1784 notes.

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