Decimation (Agency Problem Heuristic)
Taleb uses Roman decimation to discuss an agency problem: someone may benefit from abandoning a group while others bear the loss. He presents the threat of shared punishment as a deterrent; the example raises questions about incentives, responsibility, and collective punishment.
THE IDEA
THE ANCIENTS AND THE STIGLITZ SYNDROME
The Stiglitz syndrome, as used here, concerns people benefiting from decisions while avoiding their downside. In fact they had quite sophisticated mechanisms to counter most aspects of agency problems, whether individual or collective (the circular effect of hiding behind the collective). Earlier, I mentioned the Romans forcing engineers to spend time under the bridge they built. They would have had Stiglitz and Orszag sleep under the bridge of Fannie Mae and exit the gene pool (so they wouldn’t harm us again).
The Romans had even more powerful heuristics for situations few today have thought about, solving potent game-theoretic problems. Roman soldiers were forced to sign a sacramentum accepting punishment in the event of failure—a kind of pact between the soldier and the army spelling out commitment for upside and downside.
Assume that you and I are facing a small leopard or a wild animal in the jungle. The two of us can possibly overcome it by joining forces—but each one of us is individually weak. Now, if you run away, all you need to be is just faster than me, not faster than the animal. So it would be optimal for the one who can run away the fastest, that is, the most cowardly, to just be a coward and let the other one perish.
The Romans removed the soldiers’ incentive to be a coward and hurt others thanks to a process called decimation. If a legion loses a battle and there is suspicion of cowardice, 10 percent of the soldiers and commanders are put to death, usually by random lottery. Decimation—meaning eliminating one in ten—has been corrupted by modern language. The magic number is one in ten (or something equivalent): putting more than 10 per cent to death would lead to weakening of the army; too little, and cowardice would be a dominant strategy.
And the mechanism must have worked well as a deterrent against cowardice, since it was not commonly applied.
The English applied a version of it. Admiral John Byng was court-martialed and sentenced to death as he was found guilty of failing to “do his utmost” to prevent Minorca from falling to the French following the Battle of Minorca in 1757.
When to use it
Analyzing how military discipline distributes the consequences of individual and group failure.
Examining team incentives for contribution and free-riding, including whether responsibility is assigned fairly.
Risk management in financial institutions to align executive incentives with long-term stability.
Organizational policies to discourage blame-shifting and encourage personal responsibility.
FROM THEORY TO EVERYDAY LIFE
In practice
Roman Bridge Engineers
Taleb recounts the Romans requiring engineers to spend time under their bridges as an illustration of making a designer share the consequences of failure.
Sacramentum Oath
Roman soldiers signed a sacramentum accepting punishment in case of failure, committing to upside and downside.
Decimation
Taleb describes decimation as killing 10% of soldiers and commanders by lottery after a defeat suspected to involve cowardice. He argues that the threat changed incentives; the account does not independently establish its effectiveness.
Admiral Byng Case
In 1757, Admiral John Byng was court-martialed and sentenced to death for failing to prevent Minorca from falling to the French.
A MOMENT TO REFLECT
Put it to work.
What does this historical example suggest about shared consequences, and where would the analogy fail in a modern team?
What are the ethical implications of using collective punishment to deter individual failures?
In what ways do modern incentive systems fail to prevent 'cowardice' in group projects?
CONTINUE THE CONVERSATION
Source texts
- Antifragile (Nassim Nicholas Taleb)