Should the Rational Public-Spirited Person Vote?

Eric Posner:

Ilya says yes, drawing on this very interesting article of his. Here is his explanation (inspired by Derek Parfit):

Assume that Uv = the expected utility of voting; Cv = the cost of voting; and D = the expected difference in welfare per person if the voter’s preferred candidate defeats her opponent. Let us further assume that this is a presidential election in a nation with 300 million people; that the voter’s ballot has only a 1 in 100 million chance of being decisive (Riker and Ordeshook 1968); and that the voter values the welfare of his fellow citizens an average of 1000 times less than his own. Thus, we get the following equation:

D*(300 million/1000)/(100 million) – Cv = Uv.

If we assume that Cv is $10 (a reasonable proxy for the cost of voting) and that D is $5000 (this can incorporate monetary equivalents of noneconomic benefits as well as actual income increases), then Uv equals $5, a small but real positive expected utility.

If you care about the well-being of others, even a little bit, you should vote, despite the cost of voting. The reason is that the cost of voting is very low, while the benefit is not as low as you might think. Although your chance of breaking a tie is very low, the benefit from breaking a tie is very high—it’s felt by 300 million people. This multiplier effect offsets, to some extent, the very small chance that your vote will make a difference.