Gresham’s law
Etymology
Named for Sir Thomas Gresham, a sixteenth-century English financier and advisor to the Crown, though he neither discovered the effect nor stated it in the famous form. The observation is much older — Copernicus described it earlier, and it appears in Aristophanes — and the tidy phrase "bad money drives out good" was attached to Gresham’s name only in the nineteenth century by economist Henry Dunning Macleod. It is a classic case of a law credited to the wrong person, or "Stigler’s law" in action.
noun phrase · /GRESH-umz law/
The principle that "bad money drives out good" — when two forms of currency are forced to trade at the same official value, people hoard the better one and spend the worse.
What it names
A broader dynamic in which anything overvalued by a rule pushes out the genuinely valuable — why debased coins circulate, and by extension why cheap talk can crowd out honest signals wherever both are treated as equal.
Example
When the platform paid the same for a thoughtful review and a one-line rave, Gresham’s law kicked in and the feed filled with lazy praise.
Related idea
Gresham’s law works only when an external rule fixes the exchange rate; where prices float freely, arbitrage does the opposite, pulling values toward what things are actually worth.