A qualification to David Deutsch’s argument about proportional representation

In The Beginning of Infinity, physicist David Deutsch channels Karl Popper to argue that the best way to make progress and advance the state of human knowledge is not to seek knowledge from the best oracles, but rather to figure out the best way to “detect and eliminate error” (209), recognizing that all oracles of knowledge are ultimately fallible.

Applying this principle to politics, Deutsch argues that majoritarian plurality electoral systems are preferable to proportional representation parliamentary systems. This is because proportional representation systems produce legislatures with a strong multi-party system in which no one party ever enjoys a majority. Thus, policies from proportional representation systems are inevitably the result of strong compromise, making it difficult for voters to know who to hold accountable when they produce bad policies.

Also, while we commonly think of compromise as a good thing, he argues that:

The key defect of compromise policies is that when one of them is implemented and fails, no one learns anything because no one ever agreed with it. (346)

Instead, he argues that the institutions of a political system should function to make it easy to detect and eliminate error. This is more likely to be the case in majoritarian plurality systems where it is easy to hold the majority accountable for their performance and easier to replace them if that performance is judged poorly.

Following a plurality-voting election, the usual outcome is that the party with the largest total number of votes has an overall majority in the legislature, and therefore takes sole charge. All the losing parties are removed entirely from power. This is rare under proportional representation, because some of the parties in the old coalition are usually needed in the new one. Consequently, the logic of plurality is that politicians and political parties have little chance of gaining any share in the power unless they can persuade a substantial proportion of the population to vote for them. (347)

While this is an interesting argument, in my view it is also somewhat incomplete because electoral systems do not exist in a vacuum. The ability to efficiently replace governments that promote bad policies is also highly dependent on whether the democratic political system has a presidential or parliamentary system.

In the United States, for instance, we have a presidential majoritarian plurality system. In order for policies to be enacted, they must be supported by a majority of the House, Senate, as well as the presidency. In instances of “unified government,” where all are controlled by the same political party, it is indeed easy for voters for determine who to remove if policies are not working: the majority party in power. Such conditions of unified government are rare, however. Much more common is for Congress to be controlled by one party and the presidency to be controlled by another. In these situations, they blame each other for bad policies, making it difficult for voters to know who to hold accountable for poor performance.

In contrast, parliamentary systems combine the executive and legislative powers into a single entity. When policies are bad, voters know who to hold accountable: the coalition government in power. They also know more easily who to replace at the next election. This often produces a system that is often more likely to be responsive to voters who are more easily able to hold the government accountable for bad policies, often incentivizing better outcomes on the part of elected officials.

In sum, judging whether or not proportional representation or majoritarian plurality systems do a better job of detecting and eliminating bad policies requires, in my view, additional knowledge of the context and institutions where those policies are created.


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