Jim Holt in the New York Times raises the old question of whether it is rational to vote . The issue is this (for those who don’t know): the rational voter decides what to do by weighing the expected cost and benefits of actions. Suppose I value the victory of Party X at $1000. In working out the expected benefit of voting, I also have to take account of the probability of my vote making a difference, a probability which is extremely low (say 1/100,000). Assigning, therefore an expected benefit to voting of 1c, I see that going to the polling booth involves an expenditure of time, shoe leather and incurs the opportunity cost of missing a few minutes of my favourite soap opera. Since these costs will certainly by incurred if I vote, and dwarf the expected benefit of voting, the expected net benefit is always negative, and so, rationally, I shouldn’t vote.
What’s wrong with this argument? Well, one thought, which I remember hearing first from my friend Alan Carling, is this: the argument involves inconsistent assumptions about rationality. The assignment of a low probability to my vote making a difference assumes what the conclusion of the argument denies, namely, that rational persons would vote. But the argument says they wouldn’t. Well if they wouldn’t then I would be the only voter (a dictator, in effect). In which case I would certainly be rational to vote since I can count the full expected benefit of $1000 in favour of doing so. But if that’s the case, and I should vote, then so should everyone else … in which case I shouldn’t … in which case nor should they … in which case I should ….