The Median Voter Theorem (1948)

Why politicians move to the center

Black, D. (1948). On the Rationale of Group Decision-Making. Journal of Political Economy 56 (1), pp. 23-34.

In public choice economics, the median voter theorem states that

“In a majority rule voting system, the candidate/party most preferred by the median voter will be elected”

In other words, the favorite candidate of the person in the middle of the probability distribution picks the winner of the election. The prediction of the model, therefore, is what intuitively seems questionable (given today’s politics), namely that:

Candidates will position themselves around the center.

The theorem rests on two core assumptions:

• That candidates/parties may be placed along a one-dimensional political spectrum; and

• Voters’ preferences are single-peaked, meaning voters have one alternative they prefer over the other;

History

The dynamics and predictions of the median voter theorem made their first appearance in economist Harold Hotelling (1895-1973)’s legendary 1929 paper Stability in Competition in whi…