Some trucks carry signs that say, "Alarm and lock system not subject to the driver's control." The time lock on bank vaults serves much the same purpose, as does the mandatory secret ballot in elections. So does starting an invasion with a small advance force that, though too small and premature to win the objective, attaches too much "face" to the enterprise to permit withdrawal: the larger force can then be readied without fear of inviting a purely deterrent threat. At many universities the faculty is protected by a rule that denies instructors the power to change a course grade once it has been recorded.

DEFINE: This example cluster illustrates the concept of precommitment devices across domains — locks, secret ballots, military advance forces, and grading rules all make withdrawal or reversal costly or impossible.

Thomas C. Schelling, The Strategy of Conflict, loc. 714