Instant Runoff fails to elect "most acceptable" candidate (who also happens to be a "beats-all" winner)

By Dave Ketchum (with light editing by W.D. Smith)

Governing magazine published a piece (7 Feb 2008) about Instant Runoff Voting containing many inaccurate claims. Here Ketchum refutes one of their more egregious errors.

The article's claim that Instant Runoff (IRV) elects "the person who is acceptable to the largest number of people" is false. (That would, however, have been a correct description of approval voting.)

Here is a counterexample:

#voterstheir voteExplanation 35H>W>CThey would like to live where it is HOT 33C>W>HThey would like to live where it is COLD 32W>others They like WARM, but neither HOT nor COLD

Thus:

IRV will discard the WARM voters and declare: A majority of those we are still counting like HOT, so HOT wins.

So IRV in this example elects HOT, even though the largest number of people (100% in fact) find WARM acceptable. Q.E.D.

Also, note that a 67:33 majority prefer WARM over COLD, and a 65:35 majority prefers WARM over HOT, so surely WARM is the "true majority winner." But nevertheless IRV refuses to elect WARM. That also refutes the commonly-heard claim that IRV "elects true-majority-winners."


The same false claim was repeated in, e.g, this Steven Hill piece "Instant Runoff voting is catching on": the false quote there is "Instant runoff voting ensures that officeholders are elected with a majority of the vote." This myth is traceable to he so-called "Center for Voting and Democracy" (where Hill was a major actor) and unfortunately is often repeated.

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