Does virtue matter in American politics today? In his closing remarks on the second day of the Senate’s trial of President Trump, Rep. Adam B. Schiff (D-Calif.), one of the House impeachment managers, made an earnest plea for its continuing relevance, arguing that for all the talk of checks and balances in our system, the U.S. government depends on the decency of politicians — on their ability to call out wrong behavior by their peers. “If right doesn’t matter, we’re lost,” Schiff said. “If the truth doesn’t matter, we’re lost. [The] framers couldn’t protect us from ourselves if right and truth don’t matter.”

Part of what made Schiff’s appeal stand out was its somewhat archaic tone: Such moral language has been largely lost in the chaos of contemporary politics. But the absolute necessity of virtue, character and a commitment to moral principle — for citizens, yes, but especially for those who would wield political power — has been central to the views of political theorists for centuries, even millennia.

I teach and write about the history of political philosophy for a living, so I know firsthand that many students find the language of virtue in politics to be antiquated. My students tend to take for granted (at least at the beginning of the term) that someone does not need to be a good person to be a good leader. It is hardly just students. Rudolph W. Giuliani has scoffed at the notion that character should be a criterion for selecting representatives. “If we can impeach based on moral judgments, everybody in the United States Congress would have to get impeached,” the president’s lawyer told CNN.

We could take the long view, along with Plato, and argue that it is the destiny of mature democracies to become indifferent to truth and virtue, as happened to Athens during the Peloponnesian War. Plato argued that democratic citizens lose their interest in and ability to distinguish truth from falsehoods over time because democracy gradually, but surely, erodes the honor attached to experts and moral role models. Looking at more recent political history, one might argue that President Richard Nixon’s moral failings of leadership might have exacerbated the tendency to distrust authorities. Along these lines, Democrats’ defense of President Bill Clinton two decades ago relied partly on an explicit separation of character from notions of effective leadership — an idea that might have been absorbed into the civic ethos. “You may think Trump is a narcissistic, morally challenged, belligerent cad who has no business being president,” wrote a contributor to the Christian Post. “ … But whatever you think — and however you vote — America will certainly survive and is, in significant ways, thriving under a Trump presidency.”

While there is a case to be made for separating morality and politics, the ascendance of this view has obscured earlier arguments that placed primacy on the sound character and considered moral judgment of politicians. If, in fact, our political system depends on leaders and voters of sound character — as the American founders, among others, believed — we detach ourselves from the older tradition at our peril.

That tradition extends all the way back to the respective founders of Sparta and Athens, Lycurgus and Solon. Lycurgus stressed the importance of virtue, making it the central teaching in compulsory schooling for citizens. According to Plutarch, he provided students “with proofs and examples of good conduct” so that “from their youth up, the people would hardly fail to be gradually formed and advanced in virtue.” Solon described the goal of the legislator as to act with “force and justice working both in one.”

The Greek tradition of bringing together political power and moral virtue would culminate in Plato and Aristotle. Plato’s Socrates, in “The Republic,” would empower philosopher-rulers — extraordinary leaders distinguished by their wisdom and virtue. Plato’s student, Aristotle, while skeptical to a degree about philosopher-rulers, accepted his teacher’s verdict on the importance of virtue for political elites. To be sure, this emphasis on virtue rested on some precarious assumptions about how easy it would be to locate incorruptible citizens. Later in his career (in his “Laws”), Plato conceded that only gods could rule with perfect wisdom and virtue — and therefore checks and balances were essential to curb humanity’s flaws. But even for this more practical and somewhat cynical Plato, any “lawgiver worth much of anything, will never set down laws with a view to anything but the greatest virtue.”

The ancient Greek legacy of insisting — as much as one humanly can — on uniting sound character with power would persist well into the 18th century. One of the founders’ favorite sources, Montesquieu, wrote that the defining element of republics is their commitment to “virtue,” which he defined as “a continuous preference of the public interest over one’s own.” Insofar as citizens, and especially their rulers, can maintain this virtue, republics will thrive.

This tradition was embraced by the American founders, who unsurprisingly have been frequently cited in the impeachment trial. These citations have included discussions of Alexander Hamilton’s description of impeachment standards, as well as references to the founders’ great fear of elevating demagogues and tyrants to power. Yet we should not forget the attention they also gave to the role of civic character in republics. They believed, as James Madison put it in one of the most often-cited lines from all the Federalist Papers, that “if men were angels, no government would be necessary.” Thus, as with Plato, the acute need for checks and balances.

But like the mature Plato, the founders ultimately understood that those checks would not suffice. In Federalist No. 55, Madison acknowledged “a degree of depravity in mankind which requires a certain degree of circumspection and distrust,” but at the same time he insisted that “there are other qualities in human nature which justify a certain portion of esteem and confidence. Republican government presupposes the existence of these qualities in a higher degree than any other form.”

Hamilton, in Federalist No. 76, wrote that the sort of government he and the other Federalist authors proposed rested on the assumption “that there is a portion of virtue and honor among mankind, which may be a reasonable foundation of confidence; and experience justifies the theory. It has been found to exist [even] in the most corrupt periods of the most corrupt governments.”

Their belief that republicanism depends on virtue explains why the founders so frequently insisted that their constitutional order must empower those whose minds are “guided by superior virtue,” those with the “most wisdom to discern, and most virtue to pursue, the common good of the society.” Such references show that ideas like justice, temperance and wisdom are not incidental; they are indispensable to the proper functioning of the Constitution, as understood by its authors.

When Schiff appealed to the Senate on that Thursday evening, he was reminding senators (and citizens) of the Constitution’s nearly forgotten backbone. Without a commitment by enough members of the government to the essential republican virtues, “we are lost.” As Madison wrote, again in Federalist No. 55, if a purely cynical view of politicians and their followers were to prevail, “the inference would be, that there is not sufficient virtue among men for self-government; and that nothing less than the chains of despotism can restrain them from destroying and devouring one another.”

For Madison, a republic without virtue is no republic at all, and such a state would be forced to maintain civic order by force. It would have to rule by fear, rather than trust its subjects with liberty. The United States has not reached such a stage, but that is the natural endpoint the founders predicted, if “right doesn’t matter.”