I recently had a pleasant encounter with a great and outspoken American who, despite his libertarian leanings, supports Hillary Clinton for president. I congratulated him on making a tough call but allowed as how I was looking forward to casting my ballot for the Libertarian Party's flag bearers, Gary Johnson and William Weld. "It will be unadulterated pleasure," I offered, "as there is no opportunity cost."

My correspondent fired back: "Opportunity cost is Trump gets elected."

I stand by my recklessness.

Here's where the curious nature of the American Electoral College comes in handy. Even where my vote—or the votes of my 100 closest, most easily influenced "inner circle"—might swing an election, there is simply no real chance that pushing either Donald Trump or Hillary Clinton over the top in South Carolina, where I live, will determine the outcome of the presidential race. If Hillary wobbles to victory in my current state of residence, she would have already demolished The Donald in the Electoral College. Similarly, in Maryland (where our family lived until 2014), a squeaker for Mr. Trump would indicate that Ms. Clinton had been vanquished in a yuuuuuge landslide elsewhere.

Now, it is extremely unlikely that any one person's vote will rock even one state's electoral outcome. In the closest state presidential election of the last half-century—New Mexico (no, not Florida) in 2000—the final margin for Al Gore came to 366. And even that did not swing the national prize.

But set those slim odds of individual influence at the state level off to one (long-shot) side. Assuming that you live in a red or blue, and not a purple, state, you swing completely out of the loop. In its most recent election forecast, the prediction site FiveThirtyEight estimates that there is a 17.9 percent chance that Florida will decide the election (putting one of the candidates "over the top"). Next in line are Ohio and Pennsylvania, where the chances are 11.5 percent each, followed by Michigan at 8.7 percent and Wisconsin at 6.2 percent. When you account for North Carolina, Virginia, Colorado, Minnesota, Georgia, Nevada, and Iowa, you've eliminated all the states with as much as an estimated 2 percent chance to determine the outcome. Multiply that by the probability that one's own vote can throw one's state from Hillary to Donald or back, and the prospect that your vote will crown the next chief of state is neatly forecast as equal to 0.0.

This safe harbor protects 67 percent of U.S. population, that portion living beyond the aforementioned swing states. This logic is not lost on the general public, which tends to vote for third parties more often in "one-party" states.

Citizens realize that they are not trekking to the polls to cast the deciding national vote but to do their patriotic duty, taking pride in affixing an "I Voted!" sticker to their lapels and relishing the thought of canceling out some barbarian's vote (or their spouse's). But why not go commando and check the ballot for a person you'd actually prefer to see as president? In most states, the Electoral College makes this a guilt-free option.

Consequential outcomes from individual presidential votes are so unlikely that Americans cast their chief of state endorsements while investing far less in research about their choice than the investigative effort they sink to select a smartphone data plan or their next Pokemon Go venue. This is straightforward: Decisions that affect actual results generally invite more attention than those that do not. It is called "rational ignorance."

In another sense, it's liberating. Because your one tally will not change the nation's fate, you can afford to exercise your judgment worry-free. You are not at fault if Donald Trump or Hillary Clinton should win. Meanwhile, you will have indulged your conscience.

It is often said that voting third party is "throwing your vote away." It would be more accurate to say that living in a non-swing state is throwing your vote away. One tactic to recapture some modicum of vote value is to pad the total for an upstart candidate. Moreover, you might help (if modestly) to put the system on notice that the Big Two political party choices are being rejected. Even when the minor parties do not elect a president, they can thus wield power. The classic example is the Socialist Party, which garnered a paltry 880,000 votes in the 1932 election, barely 2 percent of the total cast, but over the course of the decade saw significant pieces of its platform co-opted by the New Deal. Within years, versions of the party's proposals for Social Security, a minimum wage, and large-scale public works were law.

In this year's campaign, I am insulated from liability by the Electoral College. And the presidential festivities, in my view, feature two highly undesirable major party candidates. The Founders have spared me from having to precisely calibrate my coefficient of disgust. Voting for Libertarians who have an exceedingly slim chance of victory will be the least complicated choice I will make—until Saturday's Pokemon Go selections are available.