On Monday, Rep. Jim Himes of Connecticut became the latest Democrat to come out in favor of a formal impeachment inquiry. While Himes’ position on the House Intelligence Committee makes him one of the most prominent names to call for impeachment, House Democratic leadership has remained adamantly opposed to initiating such proceedings. As Democrats continue to agonize over whether to commence a formal impeachment inquiry against Donald Trump, they are trapped between two realities.

On the one hand, if they start an inquiry, the facts already known would compel a vote to impeach. On the other hand, the Republicans in the Senate will not vote to convict, regardless of the facts.

If, therefore, impeachment cannot compel removal, and if, as Speaker of the House Nancy Pelosi believes, impeachment risks loss of the House by the Democrats and enhances the chance of Trump’s reelection, what would be the point of starting the process?

I am loath to second-guess the proven political judgment of Pelosi in resisting a formal impeachment inquiry, but that judgment should at least be informed by a fair reading of history.

And as I explain in my forthcoming book, the history of impeachments—English and American—teaches that conviction of the target officeholder is not the only measure of a successful impeachment. Indeed, impeachments that did not result in convictions often succeeded in attaining most, if not all, of the objectives of those who initiated them.

Impeachment was invented by the British Parliament in the 1300s as a tool to counteract the dictatorial tendencies of the monarchy. Parliament could not remove an unsatisfactory king short of bloody rebellion. But impeachment gave it a means to check abuses of royal power by removing—and sometimes imprisoning, impoverishing, banishing, or beheading—the officials who carried out objectionable royal policies. The American founders abandoned British impeachment’s sometimes grisly criminal penalties (in part to make impeachment more palatable) but retained the distinctive procedural features of parliamentary practice—the lower house of the legislature brings the impeachment charges, and the upper house tries them.

Through the roughly four centuries during which impeachment was in active use by Parliament, a great many officials were impeached by the House of Commons but never convicted by the House of Lords. Sometimes the House of Lords acquitted the defendant outright. More often, it simply failed to act, or the process was blocked when the monarch “prorogued” (dissolved) Parliament before a trial could be held. The Earl of Suffolk (1450), the Duke of Buckingham (1626), and the Earl of Danby (1678) were all impeached but never tried because the king prorogued Parliament. Nonetheless, for each of these men and the king he served, impeachment was a personal and political blow.

Impeachment was invented by the British Parliament in the 1300s as a tool to counteract the dictatorial tendencies of the monarchy.

The King preemptively banished Suffolk to forestall parliamentary condemnation, but Suffolk was murdered by pirates in the English Channel. Buckingham retained the King’s favor despite impeachment, but impeachment aggravated his personal unpopularity and he was assassinated. Danby was driven from office and imprisoned during the impeachment wrangling and effectively banished from public life during the reign of Charles II. In each case, the policies these men promoted on behalf of their royal masters were also impeded.

In 1715, the Earl of Strafford was impeached for giving Queen Anne “pernicious advice” about the Treaty of Utrecht. He was never tried but fell from power. His impeachment—along with that of the Earl of Oxford and Viscount Bolingbroke—signaled a decisive repudiation of pro-Catholic foreign policy and extinguished any hope of restoration of a Catholic English monarchy.

In 1787, when the Framers were gathered in Philadelphia to draft the Constitution, Parliament had just commenced the impeachment of Warren Hastings, governor-general of Bengal. Hastings’ impeachment was specifically mentioned in the exchange between George Mason and James Madison that gave us the phrase “high crimes and misdemeanors.” The trial dragged on for seven years and ended in acquittal, but the proceeding both destroyed Hastings and markedly altered the way England viewed governance of its overseas territories.

On this side of the Atlantic, impeachment was sometimes used by American colonists to protest royal policies. For example, in 1774, the Massachusetts House of Representatives impeached Chief Judge Peter Oliver for the “high crime and misdemeanor” of accepting a salary paid by the British monarchy under an act of Parliament. This seems bizarre to us, but to the colonists, the effort to pay colonial judges from the royal exchequer was an attempt to wrest control of the judiciary away from local authorities and make American judges accountable only to the faraway king.

Oliver was never tried because Colonial Gov. Thomas Hutchinson dissolved the upper chamber of the Legislature to prevent a trial. Nonetheless, Oliver became the hated embodiment of the danger of judicial servility to the monarchy. Faced with his example, no other Massachusetts judge dared to accept the king’s salary.

And although Oliver’s impeachment produced no conviction, the case assumed such importance in American minds that it made its way into the list of grievances against the king laid out in the Declaration of Independence. The king, wrote Thomas Jefferson:

… has made Judges dependent on his Will alone for the tenure of their offices, and the amount and payment of their salaries.

After the newly independent United States adopted impeachment as part of its Constitution, the House of Representatives impeached Supreme Court Justice Samuel Chase in 1804, largely for judicial intemperance and displaying partisan bias in the exercise of his judicial duties. The effort to remove him was said to be part of an attempt by President Thomas Jefferson to purge the federal bench of judges aligned with his political opponents, the Federalists. Chase’s acquittal is often cited as authority for the proposition that judges should not be impeached for their political leanings. But it had another effect, which was to admonish federal judges to stay out of partisan politics when on the bench, which they have for the most part done ever since.

Finally, the failed impeachment of President Andrew Johnson in 1868 is cited by some as both a misuse of the impeachment power and an example of the futility of impeaching a president in the House, but failing to convict him in the Senate. I disagree on both points.

Johnson plainly deserved to be impeached. He was wrong about the most important constitutional questions posed by the aftermath of the Civil War—whether to readmit the rebel states of the defeated Confederacy to full political participation in national government without thorough reform of their politics and social structure, and whether to confer on black people the rights of citizenship that the abolition of slavery necessarily implied. Johnson wanted a version of “Reconstruction” that restored the white supremacist oligarchy of the Old South to power locally and influence nationally. And he wanted to consign freedmen to a sort of permanent peonage.

The Republican-dominated Congress wanted thorough Southern reformation and far more rights for black Americans. Johnson opposed them at every turn, vetoing virtually every congressional reconstruction bill and opposing ratification of the 14th Amendment. His effort to, in effect, pretend that the Civil War never happened was the true ground on which Republicans sought his removal, even though the articles of impeachment focused on the technicality of his violating the Tenure of Office Act by firing Secretary of War Edwin Stanton.

Although Johnson escaped Senate conviction by one vote, the impeachment proceedings forced Johnson to make concessions to Congress on reconstruction. Impeachment also eviscerated his effort to secure election to the presidency in 1868. One can fairly debate whether, in the long run, the goal of meaningful Reconstruction was helped or hurt by Johnson’s impeachment. But in the short term, it made crystal clear that congressional Republicans, not the president or recalcitrant southerners, would define the postwar political order.

Against all these cases stands the supposed cautionary tale of Bill Clinton’s acquittal. It is unquestionably true that the rush to impeach Clinton over his reprehensible personal conduct and obfuscatory perjuries imposed a short-term political cost on Republicans. But the lesson of that sad episode is not that any failure to convict a president is necessarily a political disaster for his or her opponents. Rather, the lesson is that the public will punish a party that tries to remove a president on transparently trivial grounds.

To draw from Clinton’s travails the lesson that no impeachment inquiry should be attempted without a guarantee of success in the Senate is to insulate even the most egregious presidential wrongdoing from serious scrutiny, still less serious consequences, so long as he can coerce the loyalty of a craven majority of senators of his own party. To take that line not only abandons a primary constitutional defense against executive tyranny but concedes that a politically dispositive fraction of the American public is so tribalized as to be unpersuadable.

I don’t think that is the lesson of American history, at least so far. Richard Nixon resigned because congressional hearings, including a formal impeachment inquiry, convinced an initially resistant American public and their congressional representatives that he committed constitutionally consequential misdeeds. Democrat Bill Clinton was acquitted because his impeachment inquiry disclosed tawdry and dishonorable, but constitutionally inconsequential, misbehavior. In the next presidential election, Republican George W. Bush, though confronted with Clinton’s strong economic legacy, ran on restoring “honor and dignity” to the White House … and won.

Ultimately, it’s not political naïveté to believe that a voting majority of Americans can be educated to recognize the threat to constitutional governance President Donald Trump presents.

Moreover, while it is imperative that Trump be beaten, it is only slightly less important that he be beaten on proper grounds. Not merely by promising better health care, or a more rational and humane immigration system, or a moderately improved system of allocating the vast wealth generated by robust capitalism. The constitutional health of the country requires that he lose, in significant part, because a voting majority of the American people understands that, unless repudiated, Trump and Trumpism will destroy the Constitution. Democrats can’t do this if they don’t at least try to make the case, and history suggests that the risks of such an effort are lower than they seem to fear.