Q. I’m disgusted by the leading political candidates for president. I’m tempted to sit this one out. Do I have a moral obligation to vote in November?

A. We all have an obligation — indeed, a grave obligation — to work for the common good of our country. The office of president contributes significantly to our country’s common good. So we ordinarily have an obligation to vote in presidential elections. I say ordinarily because the obligation is not absolute.

In the system as it presently exists, the choice of president essentially is made between only two candidates. If after careful investigation we judge that neither party’s nominee represents any evidential advantage to the common good over the other, then we have no obligation to vote. If, however, one of the candidates and the party he represents clearly pose a greater threat to the country’s well-being, even if the other candidate and his party are undeserving in many ways, we should vote for the less unworthy candidate in order to prevent the worse from being elected.

Some have argued that we should be entitled to cast a “negative vote,” in which case the vote would be subtracted from the total of the candidate toward which it was cast. Presently, we have no such option. In its absence, voting for the less unworthy candidate acts as a kind of negative vote.

What about voting for a more worthy third-party candidate? Such voting is usually symbolic, a kind of “purity” vote, more for ourselves and our own reputations than for the common good. I say usually because if significant numbers vote for the same third-party candidate, it could indicate his viability for vice president (or presidential appointee) or for a future presidential run, or even — what is to be hoped one day — the burgeoning viability of a three-or-more party system to replace our badly corrupted two-party system. But we’d have to know in advance that such numbers were opting for an alternative candidate before we could have confidence that our vote could offer realistic benefit to the common good.

You might reply: But given that candidates win by total electoral votes and not popular votes, what if I live in a state where I am certain that a majority of citizens will not vote for the less imperfect candidate, may I then vote for a nonviable alternative?

If I am certain that my vote cannot help prevent the worse candidate from being elected, then I have no obligation to cast a negative vote against him. But I usually should still vote.

As moral theologian Germain Grisez writes, “since politics is an ongoing process, votes can have important political effects even when not decisive. The size of the vote by which a candidate wins often affects the candidate’s power while in office. Hence, it usually is worthwhile to use one’s vote to widen the margin by which a good candidate wins or narrow the margin by which a bad one wins” (Living a Christian Life, 870).

Some might be tempted by the thought that voting for the less undeserving candidate would still be evil because even though he’s not as bad as his opponent, he’s still quite bad. If we were to come to this judgment, then of course we couldn’t rightly vote for him. But we’d want to make sure that our conscientious objection did not arise from moral confusion. Voting for imperfect candidates — something we’re always required to do — is not wrong in itself, unless we vote for them because of their evil political convictions.

Now, if some candidate promised only harm to the common good — say, for example, the devil was running for office — then there’d literally be no good reason to vote for him. Voting for the devil could only be motivated by ignorance, bad will, emotion or arbitrary factors, such as the way he looks or dresses (after all, the devil does wear Prada). But human candidates exist on a spectrum of good and evil.

At least two sets of good reasons exist for voting for the less imperfect candidate in the upcoming election: first, achieving the good things he does support; and, second, avoiding the evils that the worse alternative threatens.

What about the evils the imperfect candidate threatens? Well, if his election, too, promises very grave evils and minimal goods, then we can only have weak reasons for voting for him. But if the evils his candidacy threatens are clearly less grave than his opponent’s, then those evils can and sometimes should be legitimately accepted (although we could never rightly intend them) as unwanted side effects of achieving the better outcomes made possible by his opponent’s defeat.

Does this mean that it’s always morally licit to vote for any candidate so long as he supports at least one good thing? I don’t think so. The advent of legal abortion — it seems so long ago now, doesn’t it? — was an ethical watershed in American politics. Any candidate for public office, and especially for high office, defending abortion’s legality effectively disqualified himself as a morally licit alternative. The entire reality of the political order “is directed to the permanent realization of the common good” (Pius XII, Christmas message, 1942). Abortion on demand — the intentional killing of unborn children — is as great a violation of the common good as any of the greatest evils ever socially instituted.

Are you sick of being derisively called a one-issue voter? So am I. But the way to change this is not to begin voting for confused or craven abortion defenders; rather, it’s to relegate the public defense of this sanguinary crime to history’s ethical ash heap with other atrocious-but-once-socially-acceptable practices such as chattel slavery and human sacrifice.

Finally, what about the objection that since my singular vote is unlikely to have much impact for better or worse on the common good, there should be no obligation to vote; that, like I am entitled to let other people serve in the military to supply our country’s protective functions, I should be able to let other people vote to keep our country’s election processes running?

This analogy could only work (if at all) during peacetime, when defending the country may be done by a smaller group of reasonable citizens. But during times of war, every able body must rise and defend his country.

Make no mistake, we’re in a time of political war. The enemy has the high ground. He rules our public discourse and — most damningly — our public education. He has even made stable inroads into our personal domains. Through media and social communications, he’s literally in our faces all the time, even in the safety of our homes, even in our children’s bedrooms. The disputed territory? Our souls — ours and our children’s minds and hearts. If this were physical wartime, the able bodied would have an obligation to enlist.

But — you instinctively reply — we’re not winning this war, and we’re certainly not going to win it with my one vote. And neither presidential candidate is on our side!

Those statements are true but shouldn’t be absolutized.

Although both candidates may flout good morals, it might be the case that one is manifestly worse. If so, voting for the alternative — while “holding one’s nose” — can be a genuine expression of advancing the common good. Moreover, as Christians, we remember our hopes don’t rely on the outcomes of elections. We do the best we can and leave the rest to Providence, which uses the affairs of men to accomplish divine plans.

We know that the nations will only rage against the Lord and his anointed for so long before they’re held to account. And that, for his faithful ones, for those who did what they could to oppose evil; who in every small plot of soil planted seeds of goodness, beauty and truth; who trimmed their lamps and brought extra oil, and who constantly stayed awake; those, in other words, who cooperated with the Lord as best they could in the building of his glorious kingdom: There awaits a redeemed citizenry, a new and transformed political community in the New Heaven and the New Earth, where charlatans and demagogues no longer rule; and where God’s will is the only high ground; and where our tiny seeds, planted in faith, will be found again visible as mighty oaks, dominant and lovely; and where voting will be no more.

But in the meantime, you and I can know this much: that in casting a conscientious vote, we will at least encourage one another, and other Christians, and other citizens of goodwill. We know, too, that, to our country’s credit, our vote will surely be counted; and that even if we’re unable to cast it in favor of a genuinely good man, we can cast it against an even worse one.

Indeed, the Golden Rule (“do unto others …”) obliges us to vote, especially if we’re living in a swing state; for if we don’t, we who are conscientious enough to be bothered by all the evil around us, indeed bothered enough to be tempted not to vote, then who will elect our new president? If every conscientious person reasoned his way out of voting, then surely this already sad state of affairs would get manifestly worse. So in short, we should vote in November; and — barring a fundamental conscience objection — we should vote so as to prevent the worse of the two candidates from getting elected.