Nathan J. Robinson has a post up at Current Affairs titled & Politics"Why Leftists Should Have No Problem Voting For Hillary Clinton." I ran across it after several friends shared it on Facebook, and it is among the more thoughtful analyses I have seen regarding the complexities of reconciling one's personal convictions with the practical options available.
Robinson's approach to the question of whether voting for the lesser of two evils validates the entire system and assures that those two evils will continue to be the only available options is particularly interesting:
A third criticism of lesser-evilism suggests it passively accepts the bipartisan status quo. According to this perspective, mainstream Democrats are constantly attempting to cajole leftists into voting for their “lesser evil” candidates, and so long as leftists keep obliging, they will forever be sacrificing any possibility of realizing their own agenda. If leftists are willing to fall in line behind any Democrat, however loathsome, they will eliminate their own ability to pressure the party for meaningful change. Leftists therefore need to threaten to stay home, or to vote third-party, so that centrist Democrats are forced to make concessions.
This objection accepts the position that voting should be strategic. But it is mistaken, in that it views “voting third-party” as necessarily advancing left-wing political goals. Here’s the important thing to remember about American elections: you either win them or you lose them. If Jill Stein gets 3% of the vote, she does not get to control 3% of the Executive Branch. She gets to control precisely the same amount as she does now: none of it. Unless there is a plausible world in which a third-party candidate could win the electoral college, no number of socialists voting for a third-party candidate will produce a useful electoral outcome. There are simply not enough socialists. Voting for a third-party presidential candidate must therefore either (1) be purely symbolic or (2) increase the likelihood of achieving left-wing outcomes even while losing.
Pure symbolism is a poor reason on its own. It’s hard to defend risking the well-being of every Muslim American for the symbolic value of a slightly-less-of-a-landslide loss for the Green Party. The only remaining theory, then, is that voting third-party helps left-wing political goals in some other, non-symbolic way. But it’s not clear how it does so.
The bit I would add here (and Robinson does touch on is a bit later in his piece) is that this sort of approach treats the vote for President as if it is the only lever available to affect public policy. The presidency and the Executive Branch are obviously important, but that's only one branch of government, and that is only at the federal level. When you factor in the state and local levels of government, the number of elected offices and the frequency of opportunities to vote in this country are somewhat mind-boggling. Want to really influence the Democratic Party to move in a different direction? Join it and start pushing. In a lot of places, you and two pizzas' worth of like-minded friends could probably take over your local party.