Four years ago, when the Democratic and Republican parties nominated for president two remarkably untrustworthy, unpopular, and unprincipled candidates, I was one of the more than 7 million voters who cast my ballot for someone other than Donald Trump or Hillary Clinton. In so doing, I was repeatedly told, I was squandering my vote, throwing it away on a candidate who couldn’t possibly win the White House — an unconscionable act of civic irresponsibility in a year when so much was at stake. In the weeks leading up to the election, hearing that I intended to vote for the Libertarian candidate, agitated Trump backers implored me to see that I would be helping to elect Clinton; fervent Clinton supporters warned that a vote for anyone but the former secretary of state was effectively a vote to send Trump to the White House.

Again and again I was told: “Don’t waste your vote.”

I didn’t waste my vote. Nor will I do so next month, when I again mark my presidential ballot for the Libertarian candidate — this time, the entrepreneur and academic Jo Jorgensen.

Is a vote a terrible thing to waste? Absolutely. But is it wasting a vote to cast it for the candidate you like best, even if that candidate will lose? Absolutely not.

Michele Obama disagrees. “This is not the time,” the former first lady told viewers during the Democratic convention in August, “to withhold our votes in protest or play games with candidates who have no chance of winning.”

But if 2020 isn’t the time for voters to find a better option than the Republican and Democratic parties that have turned American politics into such a dysfunctional mess, when will it be time? Four years ago, the two legacy parties coalesced behind the most widely disliked candidates in the modern era. Now we have “the second straight presidential contest in which both candidates are viewed negatively by a majority of voters,” the New York Times noted in June. One in four Americans believes that neither Trump nor Joe Biden would be a good president, according to Gallup; never has such a large share of the electorate felt that way about both major-party candidates.

So which Americans are really wasting their votes? The ones who help elect a candidate they don’t believe is fit for the job, primarily because they hate the other candidate more? Or the ones who give their support to a candidate they would be happy to see elected, because they share that candidate’s values and agree with many of her policies?

Telling Americans that they waste their vote when they support candidates with “no chance of winning” is profoundly antidemocratic, in two ways:

First, it amounts to claiming that it’s only legitimate to vote for a candidate who is “electable” — that is, to vote not for the candidate you support but for a candidate you think other people support. The planted axiom is that the major parties have a presumptive claim on every citizen’s vote, and that a voter who resists that claim by voting for a third party has done something disreputable.

Second, it disregards the power of minor parties in a democracy to influence public discourse by raising issues that major parties prefer to ignore. US history is replete with examples of once-radical views that became mainstream through the efforts of third parties — from the antislavery platform of the Free Soil Party to the Socialist Party’s demand for a government old-age pension to the push by the Progressive Party for the direct election of senators. I’m voting for the Libertarian Party not because I hope to see a Libertarian capture the presidency, but because I hope to see (some) Libertarian ideas gain traction in the political arena.

To cast a ballot for the Libertarian Party’s Jorgensen (or for Howie Hawkins of the Green Party or Don Blankenship of the Constitution Party) is not to “play games,” as Michelle Obama scoffs, nor is it to waste a vote. It is to act out of principle. It is to use the franchise affirmatively, not merely to settle glumly for the lesser of two evils.

The impact your single vote for president will have on the election is, for all intents and purposes, nil. There are only about 12 battleground states, and even there, the likelihood of any individual’s vote meaningfully affecting the results is vanishingly low. If you dislike what the major parties are offering, there is no mathematical or strategic reason not to vote for another candidate you like better: The odds are 60 million to 1 against your vote changing the outcome of the presidential election. In a small local contest far down the ballot, a handful of votes can be decisive. But in the presidential race, voters have no reason not to heed their conscience.

If your conscience urges you to vote for Trump or Biden, by all means do so. And if your conscience tells you not to vote for either of them, then by all means don’t. “Let each citizen remember at the moment he is offering his vote,” wrote Samuel Adams in the Boston Gazette in 1781, “that he is not making a present or a compliment to please an individual — or at least that he ought not so to do; but that he is executing one of the most solemn trusts in human society.” To cast your ballot for a candidate or party you don’t support is a betrayal of that trust. Even worse, it’s a waste of your vote.

(Jeff Jacoby is a columnist for The Boston Globe).