The following is a long comment I wrote on a Facebook thread months ago arguing against a left-wing friend that--in swing states--one should vote for Hillary Clinton over, say, Donald Trump. I find the arguments of leftists that one shouldn't vote for a "lesser evil" to be logically and morally imbecilic.
To the argument that because Democrats are terrible, like Republicans, one should not try to keep a worse person out of power by voting for some Democrat, there is a simple response. First, ask yourself if, say, net neutrality is an important issue. Most leftists will say it is. Because it is. So then reflect on the fact that Obama's FCC voted in favor of net neutrality along party lines: the three Dems voted for it, the two Reps didn't. And the reason there were three Dems is that we had a Democratic president. So, in effect, by voting to keep Obama in power in 2012, the country got net neutrality. To me, that argument--and one can substitute many other things for 'net neutrality'--is decisive.
Here's another argument. Suppose the election were between two terrible people: Clinton and Ted Cruz. Should one not vote for Clinton? Well--in a swing state--if one refrains from voting altogether or votes for a third-party candidate, one is effectively voting to carpet-bomb Syria. Because that's what Cruz wants to do. That is literally what one is doing; that is the effect of such a vote (or non-vote). To enable the worst candidate. Similarly, one is voting for REVERSE action on global warming. And so on. There is no such thing as "not voting"; by not voting, one is, in effect, only voting for the worst outcome. That doesn't seem sensible to me.
As for "lesser evil is still evil": yes, fine, of course it is. But if you're looking for purity in politics, you're not familiar with the world. Even a far-left candidate is always going to be inadequate, is going to have political sins in his past, is not going to be strong enough on certain issues while being too preoccupied with less important ones, and if elected to office will inevitably do some things that will outrage his former supporters. So even a left-wing candidate is effectively a "lesser evil." And yet, presumably, many leftists would vote for him.
Which means that the issue here--contrary to what everyone thinks--isn't lesser evilism; it's "Does the candidate subscribe entirely, or almost entirely, to my ideas?" And, to me, that seems like the wrong litmus test. No candidate will ever be a near-perfect reflection of one's own values. But since politicians have enormous effects on the world--and since, as Chomsky says, small ideological differences in a system of colossal power have large effects on the population, determining millions of people's lives--one should (in swing states) hold one's nose and vote for the least flawed candidate who has an actual chance.
With regard to the argument that voting for Democrats does nothing to build up a third-party alternative, and even has enabled the rightward shift of the Democrats in the last thirty-five years, I'll just quote something I wrote recently on another Facebook thread: "the rightward shift of the Dems hasn't been mainly because of lesser-evilism. It's been because the business community has mobilized to a massive degree, and popular movements haven't sufficiently counteracted that mobilization. Voting for one candidate or another every four years is a very marginal thing compared to all the other work that has to be done. For instance, a third party will never have great success on a national scale unless huge social movements are backing it up; and those movements don't exist yet. And, furthermore, voting for, say, Clinton in a swing state [in the general election] does not harm the prospects for such movements. If anything, they would probably fare better under a Clinton than under a Cruz or a Rubio, and would have a greater chance of influencing policy. The point, in short, is that on one day every four years we prevent the worst possible thing from happening, and all the rest of the time we devote to building left-wing movements."
We're all corrupted in every moment of the day, just by virtue of living in this society. It's an illusion to think that one is being somehow pure or righteous or ideologically correct by not voting for Sanders in the primary or Clinton in the general election (if she wins the nomination). What matter are consequences, not ideological purity. And I find it hard to deny that the consequences will be better if Sanders is elected instead of Clinton, or if Clinton is elected instead of Trump or Cruz.
To sum this up: what matters is the well-being of real people around the world, not "oh, he isn't radical enough." Not even Podemos or the Green Party is radical enough. The world consists only of evils and lesser evils.
Postscript. I'd also add that having Democrats in office is politically useful because it shows Americans the limits of reform, and thus makes possible movements like Occupy Wall Street that focus not on electing Democrats but on pushing all politicians, and the entire political economy, to the left.
From another perspective, a leftist can think of the choice between a Democrat and a Republican in terms of the question, "What enemy would I rather have in power?" Would you rather have an explicit and proud racist fascist as your powerful enemy, or a big business-coddling center-rightist who at least acknowledges anthropogenic global warming, denounces racist rhetoric, doesn't want to totally smash women's rights, doesn't want to revoke every law and administrative rule that benefits the population, and can be pushed to the left if strong popular movements force that outcome? Personally, I'd prefer the latter scenario.
In general, one of the problems with most people, apparently including most leftists (to some extent), is that they're not very good at thinking. (This fact also explains 9/11 Truthers.) I don't see why it's so hard to understand that it would be much better for humanity--and possibly even for the Left--to have Clinton in power than Trump. They're far from being "virtually indistinguishable"!