“Nobody should be allowed to burn the American flag,” President-elect Donald Trump asserted this week in a tweet. He speculated further that “perhaps loss of citizenship or year in jail” might be the appropriate penalty. His opinion sparked predictable outrage, in part because of the alleged harshness of his proposed penalties, but primarily due to Trump’s blanket denial of a right to burn our nation’s flag.

The reaction of many people who describe themselves as political “conservatives” was most surprising and it shows the degree to which these categories have become less meaningful in our politics. Many “conservatives” denounced what they deemed a disregard for freedom of speech. Senate Majority Leader Mitch McConnell cited the U.S. Supreme Court’s landmark holding “that that activity is a protected First Amendment right,” and celebrated our “long history of protecting unpleasant speech.” For his part, Rush Limbaugh sought to reassure his listeners that deep down, Trump acknowledged the constitutional the right to burn our flag, but that Trump meant merely to convey his anger at this misuse of freedom.

It is truly one of the most astounding developments that today’s conservatives have come to believe that our Constitution, rightly construed, protects the right to burn our flag. Nearly three decades ago, when a sharply divided 5-4 court first made that holding in Texas v. Johnson (1989), conservatives generally decried the decision. Justice William Brennan, writing for himself and four of his colleagues, struck down the laws of 48 states and the federal government. To challenge the decision, Congress adopted by an overwhelming vote the Flag Protection Act of 1989, which was then invalidated by the same 5-4 margin less than a year later.

One of the legislators who voted for that 1989 bill was none other than the freshman senator from Kentucky, Mitch McConnell. In his next two terms, McConnell would sponsor at least three more bills to protect the flag from desecration.

But McConnell, like many other conservatives, seems to have changed his mind. Flag-burning is just another form of “unpleasant speech” By this account there is no sound or principled basis for making and enforcing laws restricting the mutilation of the flag, any more than than there is for making and enforcing laws restricting the right to criticize Senator McConnell. Conservatives have “evolved.”

But maybe it is not evolution so much as it is forgetting that has alienated so many conservatives from the broader American political tradition. What conservatives today may have forgotten is the civic purpose of our constitutional freedom of speech—a purpose that might justify the traditional rules against flag burning.

According to the American Founders, the people of the United States constituted the sovereign political authority. These sovereign people have a right and a duty to govern themselves by “reflection and choice” and not by mere “accident and force,” as Hamilton suggested in Federalist 1.

Sovereign communities require that their members have the freedom to engage in political discussion. The very term “freedom of speech,” in our constitutional history, arose first in the English Bill of Rights to identify the right of members of Parliament to free deliberation. But when our Founders asserted emphatically that sovereignty resided not simply in the legislature but in the people at large, they likewise asserted in the new constitutions that the whole citizenry must have a right to free deliberation.

The political deliberative purpose of our freedom of speech might explain why this freedom must include the freedom to criticize current officials but not necessarily the right to attack a symbol of national unity. The nature of a republic’s deliberations presupposes the existence of a “common good”—a metaphorical table around which to discuss. We are supposed to be deliberating how to achieve that good, but that we are constituted to achieve that good is a settled question and is not up for debate apart from revolution or constitutional amendment. Our nation’s flag is a symbol of that common good. To burn that flag is like overturning the common table.

A community has a right to sanction such misconduct—not in order to suppress the discussion of unpleasant or novel opinions, but in order to safeguard the common good that is the purpose of the discussion. Put another way: the purpose of free discussion may very well impose limits on the modes of expression.

In the last century, progressives boldly challenged the Founders’ conception of free speech. They preferred to speak less of the freedom of discourse and more of the “freedom of expression”—a neologism probably introduced by Justice Louis Brandeis less than a century ago. Under the progressive conception, the freedom of speech served to facilitate not so much the community’s deliberations, but the disruption of the community itself. As the court cheerfully noted in Texas v. Johnson (quoting a 1949 case), free speech “may indeed best serve its high purpose when it induces a condition of unrest, creates dissatisfaction with conditions as they are, or even stirs people to anger.” Or as Justice Holmes said more radically in his dissent in Gitlow v. New York (1925), “[i]f in the long run the beliefs expressed in proletarian dictatorship are destined to be accepted by the dominant forces of the community, the only meaning of free speech is that they should be given their chance and have their way.”

But if conservatives seek to conserve our constitutional order, they should wary of any notion of free speech that is hostile to our national symbols. The preservation of our freedom depends entirely on the preservation of our republic—and that task, in turn, may require that we preserve, protect, and defend the leading symbol of that republic—the flag.