If the thousands of protesters chanting “Not my president!” are any indication, the U.S. president-elect’s legitimacy may be in peril.

This should not be dismissed as mere rhetorical flourish: A recent poll shows that 18 percent of Americans reject Donald Trump’s legitimacy as president.

Some critics dismiss these protesters as sore losers. More seriously, they are blamed for undermining the legitimacy of our democratic institutions. Trump won fair and square according to our agreed-upon constitutional processes; hate him all you want, as Andrew Sabl wrote here in the Monkey Cage, but you cannot reject the winner just because your side loses.

What these arguments fail to grasp, however, is that, in the United States, authority is never legitimate if it is tyrannical, no matter how unanimous the vote or impeccable the electoral process. (As Sam Goldman recently pointed out, tyranny – a concept so relevant to ancient Athenian politics – suddenly seems poised for a comeback!)

Perhaps no philosopher is more illuminating on this count than John Locke (1632-1704). In his “Second Treatise on Government,” Locke argues that government derives legitimate authority from the consent of the People. This notion — popular sovereignty — was taken up by the American founders, who used it to justify their experimental republic. “Governments are instituted among Men,” Thomas Jefferson writes in the Declaration of Independence, “deriving their just powers from the consent of the governed.”

Americans make their consent known through elections. Trump won the election. Thus popular sovereignty seems to entail that Americans must accept Trump’s authority as legitimate. Right?

Elections do not magically transfer the sovereignty of the American people to their leaders. The People retain their sovereignty. They therefore retain the authority to reject a leader’s legitimacy — even after that leader is freely and fairly elected.

This is a potentially dangerous and destabilizing idea. After all, how can government possibly endure if the People are at liberty to reject their freely and fairly elected leaders?

Before anyone starts running around rejecting elected leaders willy-nilly, know that there is a catch to this “Not my president!” business. Only when government becomes destructive to life, liberty or the pursuit of happiness is it “the Right of the People to alter or to abolish it,” Jefferson writes in the Declaration of Independence, adding that “when a long train of abuses…evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government.”

Only a lot of tyranny — a “long train of abuses” — justifies denying legitimacy to a government. This qualification would seem to significantly limit the cases in which the People could justly declare “Not my president!”

However, who has the authority to decide when things have gone from merely bad to flat-out tyrannical? Locke is unequivocal: “The people shall be judge.”

For all his emphatic italics, however, one must concede that this is barely helpful. The People, sovereign though they may be, cannot even agree on what tyrannical means. Restricting ownership of assault weapons? Putting Muslims on a registry? Preventing cattle from grazing on public land? Little stops anyone from playing the tyranny card, even for trivial abuses.

Okay, so the People can challenge the legitimacy of a sitting president based on his (and someday her) actions. But what about a president-elect? After all, Trump’s administration is not yet installed; he has not yet imposed on anyone’s liberty. It is doubtful that a “long train of [tweeted] abuses,” could fit anyone’s definition of tyranny.

On the other hand, Trump has said, among other things, that he would lock up his political opponent, deport immigrants and register Muslims. He has endorsed torture and expressed a willingness to kill the families of terrorists, which would be a war crime. We know that undivided government is imminent; therefore, such designs are imminently realizable.

Surely some people will think this to be, as Locke wrote, “manifest evidence, that designs are carrying on against their liberties.” Others will disagree.

Because Americans seem to disagree so much about what constitutes tyranny, is it a recipe for disaster if some people are prepared to refuse legitimacy so promptly? Will cries of “Not my president!” proliferate after every election, leading us to chaos and civil war?

These are valid existential anxieties, and theory is of little help here. Instead, Locke offers the practical, empirical consolation that, “Great mistakes in the ruling part, many wrong and inconvenient laws, and all the slips of human frailty, will be born by the people without mutiny or murmur.”

In other words, resistance is hard. Many people are inured to suffering and will thus bear quite a bit of it without complaint. The fact that the People have the sovereign authority to alter or abolish their government sounds frightening until you realize that, well, they probably won’t.

Yet the tendency to tolerate so much tyranny makes it all the more significant when citizens finally do become universally persuaded, with “manifest evidence, that designs are carrying on against their liberties.” If this happens, Locke asks, “who is to be blamed for it?”

This does not mean that we must believe every accusation of tyranny; we may consider citizens’ accusations and find them less than compelling. There is no easy way to arbitrate between competing conceptions of freedom. We simply must muddle through, guided by philosophy, tradition, experience and reason.

Still, if more and more People become convinced that the government is tyrannical until a majority agrees, then it is probably not the People who are defective. When legitimate authority is imperiled, we would do well to first suspect the government of being insufficiently acceptable rather than impugning citizens’ insufficient acceptance of government.

If the partisans of order are alarmed by the implications of popular sovereignty, they might find consolation in the fact that, from the Lockean perspective, protesting tyranny is more likely to preserve the republic than dissolve it.

By retaining their sovereignty, the People are a constant reminder to the government: memento mori! Take away our liberty, and we will deny you legitimacy! As such, popular sovereignty is the ultimate check on government power. Thus it is a bizarre logic that defends democratic institutions by adopting a wait-and-see approach to tyranny.

If democratic institutions are held sacred, it is not just — or even primarily — because they preserve order, but because they preserve freedom.

Trump is the legitimate winner of the presidential election. But protesters are not protesting the legitimacy of the election, but rather what they fear are the tyrannical inclinations of the coming administration. And so long as the People remain the source of sovereignty in the United States, they will always be the only ones with the authority to say: Not my president.

Whitney Mannies is a PhD candidate in the department of political science at the University of California at Riverside. Her most recent publication is “The Style of Materialist Skepticism: Diderot’s Jacques le fataliste.”