Representative Justin Amash of Michigan announced last week that he will seek the Libertarian Party nomination for president, and was instantly castigated as a spoiler working for Donald Trump’s reelection.

It is hard to think of anyone about whom such a charge could be more ludicrous.

Amash was a co-founder of the libertarian-leaning House Freedom Caucus in 2015. In Congress he became Trump’s sharpest critic on the right, voting in line with the White House position only 63 percent of the time — lower than any other House member elected as a Republican. Last summer, the five-term congressman left the GOP to become the only independent in the House; in December he was the lone non-Democrat to vote for Trump’s impeachment. Amash has never tried to hide his distaste for the president’s character and many of his policies. The president, in turn, has mocked the congressman with personal insults (“a total lightweight,” “a loser,” “one of the dumbest and most disloyal men in Congress”).

To attack Amash, of all people, as a spoiler working to reelect Trump is absurd. Yet that was the immediate reaction in the anti-Trump camp, on both left and right. “Nooo!! You’ll be the Ralph Nader of this election,” tweeted Mia Farrow, referring to the 2000 Green Party candidate blamed by many Democrats for Al Gore’s crucial loss in Florida. Republican Joe Walsh, a one-time Trump loyalist who now opposes the president, accused Amash of knowingly “helping Trump” and “putting his own interest before the country’s interests… shame on him.”

Actually, shame on Walsh and anyone else smearing Amash in such a dishonest fashion.

Certainly it is plausible that if Amash wins the Libertarian nomination, he could draw anti-Trump votes that might otherwise go to the Democratic nominee — presumably Joe Biden. In a battleground state like Michigan, Amash’s home turf, a non-Trump alternative could conceivably divert enough support to keep Biden from winning the state. Something like that may have happened in 2016. Trump edged Hillary Clinton by just 10,704 votes in Michigan — a small fraction of the 172,000 votes that went to that year’s Libertarian candidate, Gary Johnson. Supporters of Biden fear the same thing could happen again this year.

But it’s equally plausible that an Amash candidacy could inflict a fatal wound on Trump’s bid for reelection. Many right-leaning voters are weary of Trump, yet will never cast a ballot for Biden. A Libertarian alternative gives them — or rather, us, since I’m in that category — a more appealing option than voting Republican or sitting out the election.

With half a year still to go, no one can possibly know how any third-party candidacy will influence the election. But even if that weren’t true, it wouldn’t affect the legitimacy of Amash’s candidacy. He isn’t running for president in order to execute some sort of three-dimensional chess maneuver to tip the Electoral College to the Republicans or the Democrats. He is running to give voters an option in the presidential election outside the two-party duopoly. The idea that there is something disreputable in doing so is evidence of just how debased that two-party system has become.

Far be it from me to tell loyal Republicans or Democrats not to support their party’s nominees and strive to get them elected. But inasmuch as a plurality of Americans belong to neither party, why shouldn’t there be other options? And why should anybody be condemned for offering one?

In almost no field apart from politics are people denounced for providing more than a binary choice. Bartenders stock more than bourbon and vodka. Schwab doesn’t limit investors to Mutual Fund A and Mutual Fund B. No one tells Netflix that adding “Tiger King” to its lineup was wrong because it could only siphon viewers away from “Outlander” and “Never Have I Ever.”

Having more than two choices is nearly always a good thing. It is certainly a good thing in politics. Amash proposes to run for president as a “classical liberal” — i.e., a pro-freedom, limited-government, anti-authoritarian constitutional conservative. He holds himself out as an option for voters seeking a candidate who is “normal, honest, practical, and capable.” Maybe such a candidate can’t win the White House, but voters should be the ones to make that decision.

An Amash candidacy won’t “spoil” the 2020 presidential election, it will enhance it. May the best candidate win.

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