Jeff Dulgar complains in the UC Santa Barbara student paper Daily Nexus that "Unwanted Libertarians Crash the Party". He admits that the LP "has become that cool new fad", but says to LP members that "you’ve rebelled against conventional politics, but you have effectively tossed your vote aside" because they "choose to vote for a party that will never get elected".
Let's explore the infamous "Wasted Vote Syndrome". For a vote to be "wasted", it has to be cast in vain, without furthering the purpose for which it was cast. So what are the reasons for which people vote? Why do they even vote at all?
This is a surprisingly difficult question -- difficult enough that economists call it the "Paradox of Voting" (or Downs Paradox, after the seminal 1957 paper by Anthony Downs). They observe that the cost of voting is relatively high compared to its objective benefit to the voter. To vote you have to invest up to an hour of your precious time -- analyze your choices, travel to a polling place, stand in a line or two, enter your choices, and travel back. (Voting by mail only changes the time calculation a little.) Your payoff from voting has to be discounted by the probability that your vote will tip the outcome of the election. Even if you expect the outcome of an election to have a big effect on your life, the odds that your vote will change that outcome are usually vanishingly small. When you do the math, you see that the net expected personal benefit to you from adding your vote to your candidate's total is far less than the cost of the gas it takes to get to the polls -- or even the cost of the stamp to mail your ballot.
The standard explanation, then, is that voting yields some kind of psychological benefit, apart from any coldly calculated material return on the effort invested. One component of that psychological benefit is surely the basic primate need to line up with the winning side. For most of the millions of years of hominid evolutionary history, lining up with the winning faction in the tribe was often potentially a matter of life or death. Even today we're usually under social pressure not to keep our voting preference a secret. Humans have enjoyed the secret ballot for only a few centuries, and that's not nearly long enough for us to shake the feeling that we better back somebody with a decent chance of actually taking over our tribe.
A new theory was proposed in 2007 by Edlin, Gelman and Kaplan: Voting as a Rational Choice: Why and How People Vote To Improve the Well-Being of Others. They contend that "for voters with ‘social’ preferences" -- i.e., preferences about how an election will affect people other than themselves -- "the expected utility of voting is approximately independent of the size of the electorate" because bigger elections can affect more people. For such voters, the expected utility from voting will be roughly the size of the benefit that the election might provide to the average citizen, because the number of people benefiting (N) is roughly balanced by the 1/N probability of tipping the election.
The problem with this new analysis is that it only considers one election in isolation. Even on its own terms, voting for the lesser of two evils to somehow maximize your "social preference" is subject to a dizzying regression called a Keynesian Beauty Contest. The concept was first applied to equity markets, pointing out that the price of a stock will not really be what investors think is its fundamental value, but rather will be what investors think other investors will think is that value. In the context of voting, that regression may not yield a single sensible equilibrium if voters are very unsure about what candidates have the best chances of winning.
But in fact we have detailed information about the probabilities of victory for various candidates and parties, and that information is the key to recognizing the Wasted Vote fallacy. First of all, polling data and historical data about "safe" districts can almost always combine to tell you that your one vote has no real chance of tipping the outcome in the district (or electoral college state) where it will be counted. Rather than depressing you, this should liberate you to vote your conscience. So even a believer in Wasted Vote logic should only vote for the lesser of two evils when the empirical data show that one evil leads the other only by a nose (or a horn or a hoof).
However, there is a consideration that makes even that strategy suspect. Again, the way we can anticipate how many votes that a candidate or party will attract in this election is to look at how many votes that (or similar) contestants attracted in past elections. When you realize this, you understand that in a very real sense your vote in this election will influence the outcome not only of this election, but all future elections run with a similar set of candidates and voters. So voting for your habitual incumbent party in this election sends the enduring message to future voters -- and to election-watching politicians -- that there is no danger you will stop voting by habit. You have to balance 1) the alleged benefit of tinkering at the margins of the present status quo with 2) the potential huge benefit of overturning the status quo in favor of the principles you actually believe in.
Thus the only truly wasted vote is to vote by your reflexes, and not by your principles.