... is consequence that is immediate, intense, and inescapable.
The secret to deterrence is not persuasion but menace.
It is why garden variety thugs stay clear of the rough galute who is battle-scarred, twice their size, and armed to the teeth. They know intuitively that casual confrontation with this type is a bad bet, certain not to leave them feeling better than they started.
Nature teaches predator and prey to recognize each other and to make snap decisions about when to chance confrontation and when to slither away. These snap decisions happen instantly not because the decider is adept at evaluating comparative risk and reward but because he or she senses that a wrong call is fatal, hence not worth a gamble.
This is a visceral judgment rooted in the most basic instinct of all life: survival.
Academic literature reviews and arguments about deterrence tend to zero in on aspects of theoretical interest to armchair investigators. Some, like this (Tomlinson, below) do a creditable job of presenting theories to say why deterrence works under some circumstances but falls short on other occasions. What do they lack?
They lack that element of field truth that comes from being in harm’s way and directly witnessing what deters thug and crazy with equal consistency.
Such studies also miss what H. L. Mencken long ago recognized as the value of certain measures that extend beyond mere deterrence (Nordquist, below).
A lifelong cynic, Mencken harbored few illusions about human rascality and the need for keeping it in check through punitive action.
However, Mencken had the perspicacity to discern that the harshest punishments society reserves for its worst villains have more than deterrent value. He speculated that their higher value is in delivering a social catharsis that restores public confidence in a world operating as it should, with some trace of justice or fairness still intact to reassure us that we have not descended into irreversible decline.
Perhaps, then, effective deterrence requires not only consequences but also a cathartic element which functions as an emetic to purge our society of its most lethal toxins.
Finally, for a tongue-in-cheek, four-panel distillation of deterrence in action, give a cartoonist a nod. Try this online search string: "Gary Larson + how nature says do not touch."
References:
Nordquist, Richard. ""The Penalty of Death" by H.L. Mencken." ThoughtCo, Aug. 27, 2020, thoughtco.com/the-penalty-of-death-by-mencken-1690267.
Tomlinson, Kelli D. "An Examination of Deterrence Theory," Federal Probation, Vol. 80, No. 3, December 2016.
https://www.uscourts.gov/sites/default/files/80_3_4_0.pdf