The Two-Party System and the Prisoner’s Dilemma

Posted by tobymuresianu on Oct 29, 2012 in Politics, Thoughts |

Watching party politics unfold, I’m continually reminded of the Prisoner’s Dilemma, an exercise in decision-making and morality often taught in philosophy and computer science. The gist is this:

Two accomplices are arrested and interrogated in isolated chambers. They have a choice: they can betray their partner by confessing to the crime, or cooperate with their partner by remaining silent. They know their partners have the same choice, and the sentences they will receive depend on both their action and the action of their partner.

If they are both silent, they will both be convicted on a minor charge and sentenced to one month in prison. However, if one confesses while their partner is silent, the confessor will be rewarded and go free, while their partner will go to jail for a year. If they both confess, they will both be convicted and receive a three-month sentence.

This table represents the potential sentences:


Person A Silent Person A Confesses
Person B Silent 1 month each No jail time (Person A)
1 year (Person B)
Person B Confesses No jail time (Person B)
1 year (Person A)
3 months each


The key part of this is that it’s always in a person’s best interest to betray their partner rather than cooperate, because their outcome will be better no matter what their partner does. However, considering both their outcomes together, cooperating is a better option for both. This is often considered a model for how individuals acting in their rational self-interest can lead to group outcomes inferior to those where individuals act contrary to their immediate self-interest.

I think our two-party system represents a similar situation. It’s set up so that the best interest of the parties lie in not cooperating, even though the government and the country is worse off for it.

If both parties cooperate by attempting legislative compromise, they get a reasonable outcome (moderate progress towards their goals with some sacrifices). On the other hand, if neither party compromises, they both get a worse outcome (no progress towards their goals). However, if one compromises and the other doesn’t, the one that doesn’t compromise is rewarded with a better outcome (good progress towards their goals at the expense of the other party’s) and the one that attempts to compromise has the worst outcome possible (less progress than sacrifice, and poor re-election prospects).

Further hurting the situation presently are two factors. One is a history of non-cooperation that makes both parties unlikely to want to compromise for fear of getting screwed. The other is that representatives who compromise, particularly on the right, are also subject to punishment from within their own parties – with members willing to compromise being replaced with party loyalists unwilling to. The net result is that our two-party system of government discourages cooperation and rewards bad behavior.

Obviously, there are differences – there is, ideally, communication between parties and the game is played multiple times (modeled by the more complicated ‘iterated prisoner’s dilemma’). However, I believe given the way the parties are acting and with the conditions as they are, the simple Prisoner’s Dilemma is the most useful and straightforward model to use.

Most of my friends are left-wing, and they will say that while the two party system is broken, the Republicans bear most of the responsibility for breaking it. I think there is truth to this – I think Democrats were and are by nature more willing to cooperate, whereas Republicans (and especially Tea Partiers) embrace an Ayn Rand-ian “Greed is good” ethos that encourages selfish behavior. The problem is that the prisoner’s dilemma is a perfect example of why greed isn’t good – it results in poor long-term outcomes. And it’s not surprise that after getting screwed in negotiations a few times, Democrats – realizing their partners were not cooperating – chose to not cooperate themselves or take Republican gestures in good faith.

The problem is that even if you prefer the Democrats (and I’ve avoided mentioning whose ideas are better), they can’t change the situation on their own, and there are no indications that Republicans are willing to. Even if they gain a supermajority, it seems to be the tendency of Democrats to then divide amongst themselves and act our their own internal prisoner’s-dilemma situation. Witness the last time they had a supermajority, in 2008, when they were still stymied in efforts to pass bold legislation by infighting and united Republican opposition.

So what can we do about this situation? While the obvious thing is to have both parties cooperate and stop punishing cooperators, sadly, nobody is expecting that to happen. The set of rules that set up the prisoner’s dilemma situation remain intact and are only likely to make it worse.

However, there are a few changes to the system that could help.

1) Term limits for Senators and members of Congress. By reducing the threat of compromise leading to losing one’s re-election bid, you reduce the penalty for cooperation.

2) Voting in a third (or fourth) party. This raises the possibility that parties who do not cooperate expose themselves to the worst outcome – two other parties cooperating and cutting them out entirely. It therefore further incentivizes cooperation.

3) Eliminating the gerrymandering which has resulted in most congresspeople representing districts that are not competitive and dominated by party loyalists who frown on compromise.

Unfortunately, neither of the two major parties are talking about the first change, the second is against their interests, and the third problem is their creation. I see the best and most direct path toward reform to be voting for a third party, as I wrote previously here and here. But I am curious to hear your thoughts.

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