the.com/thin end of the wedge
The small harmless step that was never meant to stay small.
means A minor, seemingly acceptable change or concession that is really just the first move in a much bigger, unwanted process.
from From the simple physics of splitting wood or stone: you drive in the slender tip of a wedge first, where it meets little resistance, and once it's lodged, you hammer the thick end to force the split wide open. The phrase has been used since at least the 1800s as a warning against small concessions — the worry being that the thin part is only ever the entry point for something much larger and harder to stop.
- origin
- literal wedges split logs from the narrow end first
- logic
- tiny concession today, lever for bigger demands tomorrow
- usage
- warns against precedent, not the act itself
- fallacy cousin
- slippery slope argument's more practical British sibling