By: hctomorrow Tuesday September 14, 2010 11:36 pm

A common refrain in the lefty blogosphere is that you have to support the candidate with a D after their name, even if they repeatedly betray your causes and ideals, because the Republicans are worse. They’ll repeal all the ‘great’ legislation the Democrats have passed over the past two years, and continue all the terrible policies the Democrats have unfortunately continued – policies which are also, conveniently, the Republicans’ fault.

However, game theory teaches us something quite different – that cooperation without the threat of retaliation for betrayal is a sucker’s game.

The Prisoner’s Dilemma

To see why, let’s back up a bit. First, what’s Game Theory? From Wikipedia:

Game theory is a branch of applied mathematics that is used in the social sciences, most notably in economics, as well as in biology (particularly evolutionary biology and ecology), engineering, political science, international relations, computer science, and philosophy. Game theory attempts to mathematically capture behavior in strategic situations, or games, in which an individual’s success in making choices depends on the choices of others.

In essence, it’s roleplaying as science. To try and understand what the best strategies are when dealing with other actors, you set up a mock version, either on a computer or for kicks in real life, and play out the various strategems, measuring which is more successful and what the pitfalls are. The results can often be surprising.

One of the most famous experiments in game theory is the ‘Prisoner’s Dilemma’. Again, from Wikipedia:

The prisoner’s dilemma is a fundamental problem in game theory that demonstrates why two people might not cooperate even if it is in both their best interests to do so. It was originally framed by Merrill Flood and Melvin Dresher working at RAND in 1950. Albert W. Tucker formalized the game with prison sentence payoffs and gave it the "prisoner’s dilemma" name (Poundstone, 1992).

A classic example of the prisoner’s dilemma (PD) is presented as follows:
Two suspects are arrested by the police. The police have insufficient evidence for a conviction, and, having separated the prisoners, visit each of them to offer the same deal. If one testifies for the prosecution against the other (defects) and the other remains silent (cooperates), the defector goes free and the silent accomplice receives the full 10-year sentence. If both remain silent, both prisoners are sentenced to only six months in jail for a minor charge. If each betrays the other, each receives a five-year sentence. Each prisoner must choose to betray the other or to remain silent. Each one is assured that the other would not know about the betrayal before the end of the investigation. How should the prisoners act?

Obviously, the prisoners would be better off if they cooperated – 1 year’s combined jail time is a lot better than 10, which is the result if either betrays the other, or both do. However, it’s not *rational* to cooperate – no matter which choice your opponent makes, betraying them increases your benefit. If they cooperate, you stab them in the back and walk free. If they stab you, you protect yourself by backstabbing them.

A pretty bleak assessment of human nature, eh? The problem here is accountability, or rather, the lack thereof. Remember the setup: the police make sure neither prisoner can confer with the other until after the decision has been made, and you only get to make it once.

If accountability is added, however, things turn can turn out very differently.

The Iterated Prisoner’s Dilemma, aka Politics

If you set up a game where the players have to run through that same scenario multiple times, with memory of what happened before, things turn out differently, and different strategies succeed. If you defect every time, your opponent is free to, and indeed only rational to follow your example. Likewise, however, if you cooperate every time, your opponent can see an easy mark and take advantage.

Wikipedia again:

Retaliating
However, Axelrod contended, the successful strategy must not be a blind optimist. It must sometimes retaliate. An example of a non-retaliating strategy is Always Cooperate. This is a very bad choice, as "nasty" strategies will ruthlessly exploit such players.

Herein lies the fundamental flaw in always voting Dem just because Republicans are worse, and we have decades of math to back it up. If you always cooperate, your opponent will face enormous temptation, arguably selection pressure, to defect and betray you. It’s only a matter of time, and what’s more, they face absolutely no penalty for doing so – you’ll just cooperate again the next round.

If, on the other hand, you are willing to retaliate, a more successful strategy can be devised.

Tit for Tat
As it turns out, cooperating all the time and defecting all the time are both proven losers, given repeat performances. So what works?

It turns out, a combination of the two. I’ll let Carl Sagan explain this one (from his essay ‘The Rules of the Game’, collected in Billions and Billions):

The most effective strategy in many such tournaments is called "Tit-for-Tat." It’s very simple: You start out cooperating, and in each subsequent round simply do what your opponent did last time. You punish defections, but once your partner cooperates, you’re willing to let bygones be bygones. At first, it seems to garner only mediocre success. But as time goes on the other strategies defeat themselves, from too much kindness or cruelty, and this middle way pulls ahead. Except for always being nice on the first move, Tit-for-Tat is identical to the Brazen Rule. It promptly (in the very next game) rewards cooperation and punishes defection, and has the great virtue that it makes your strategy absolutely clear to your opponent. (Strategic ambiguity can be lethal.)

The problem for Progressives is that we’re being told to, and have in the past often utilized an Always Cooperate strategy.. and our partners in elected office learned that long ago, and are exploiting it.

On gay rights, on immigration, on financial reform, on restoring the rule of law, on putting torturers on trial, on unions and the free choice act, on escalating unwinnable wars, on fighting the legalization of marijuana, on just about any and almost every single Progressive issue you can name the current Democratic party has defected. Why?

Because it’s a winning strategy to defect if you know your opponent will always cooperate; in fact, it’s the absolute best strategy to employ.

The Way Ahead

The only way we can expect to stop the exploitation is to show our would-be-defectors in the Democratic Party that we’ve woken up, once and for all, and are willing to retaliate when defected from. Yes, if we do so, we’ll lose in this round of our iterated game. We might, in fact, lose very badly indeed.

The alternative, however, is clear, from both game theory and common sense: the exploitation will *never* stop. Never. Let’s be very clear; the current dilemma Progressives face with their estranged counterparts does not stem from a lack of understanding; the party understands us all too well. It isn’t the result of Dems failing to learn from past mistakes; on the contrary, they’ve learned exceptionally well from ours.

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