Barring a literal duel between Mitt Romney and Barack Obama between now and November 6th there won’t be a third candidate with a chance to win the presidency. Despite this many hundreds of thousands of people will vote for a third party candidate. Perhaps at the top of that proverbial list for reasons given as to why this is a good idea is a retort in response to criticism that supporters of third party candidates are wasting their vote saying “those who are really wasting their vote are those who vote for a candidate they don’t believe in.” The basic idea is to vote for the candidate which best approximates your views regardless of their chance to win. This reasoning is simple, succinct and irrational.
Admittedly it seems to make some intuitive sense to simply vote for the candidate that you believe most represents your views but voting is not actually that simple. Indeed this seems to be a clear example of the prominence effect, a focus on one goal at the expense, or exclusion, of others. In addition to how much a candidate shares your values, a rational voter should also consider the expected outcome of their vote, both in the short term and long term, and the effect of different outcomes on fulfilling their goals. It’s also fairly easy to see that these parameters don’t always align neatly.
One easy way to check this is to simplify the choices and consider there being an election with three candidates. Candidate A shares 100% of your views, candidate B shares shares 75% of your views while candidate C shares none of your views. Polling for this race shows candidate B and candidate C in a dead heat while candidate A is far behind. If you were voting simply on which candidate best approximates your views you would choose candidate A but so long as you are considering the outcome of your vote and the effects of this outcome on achieving your goals you would vote for candidate B.
While that is a simplification the reasoning is clear, sometimes the candidate which is not the most closely aligned with your views has a better chance of helping you achieve your goals. In the end the entire point of voting, or any other activity, is to achieve your goals so in situations like those in the U.S. find themselves today, with two parties in a close race and all third party candidates hopelessly behind, voting for a third party would only be a sound decision in certain circumstances: 1) You think voting for a third party candidate has benefits that outweigh or equal the potential short term and long term consequences of increasing the chance of your least favored candidate winning (perhaps you think if a certain percentage vote third party your interests will be heard more in the future) or 2) You are indifferent to the outcome of either major candidate being in power, the benefits and consequences of both major party candidates is equal to you.
This is not to say that the common question of “Which candidate do I like enough to feel good endorsing?” which third party supporters like to repeat doesn’t matter, only that normatively the narrow effects of voting for a candidate on your psyche should not be the only consideration.
A better formulated question facing voters considering third party candidates would be “Does the personal gratification I gain from voting for my preferred candidate outweigh all of the other benefits and consequences imposed on the rest of society and I by not voting for my more preferred (or least hated) of the two establishment party candidates?” The ultimate tabulation will be a value judgment but it should be clear that any rational decision must include consideration for more than simply how closely a candidate aligns with your views. Such a narrow focus on a candidates ideas isn’t a sign of being a principled or idealistic voter, rather it is a sign of an irrational decision.