The wind appears to have shifted somewhere between Air Force One and the Capitol building on Sunday, which was when Lindsey Graham, the malleable Senator from South Carolina, attempted to reclaim his status as the voice of reason. He is even harder to stomach in this reprisal of his original role as Senate moralist than he was in the first instantiation, probably because his dalliance–make that “torrid affair”–with Trumpism intervened. Graham wrote to Senate Democratic Leader Chuck Schumer to plead that the article of impeachment be dismissed without being tried. His reasoning is admirable only for its audacity.

Vice President Pence, who has not been impeached, “stood in the breach,” Graham offers, without noting that the man who is on trial, Donald Trump, opened the breach in which it was necessary for Pence to stand. Pence “resisted immense and unprecedented partisan pressure,” pressure whose source (Trump) Graham fails to specify, probably because Graham also knows he did nothing to alleviate it.

Should, Graham asks, the Senate have impeached the retired President Obama and disqualified him from future office because of his handling of Benghazi? Here we arrive at the heart of the matter: Those who would derail impeachment in the name of “national healing” (Graham, supra) have not faced the gravity of the offense. This was not an incompetently handled attack on an embassy. This was not even rank bribery. It was–have we already lost sight of this?–a direct and nearly successful assault on constitutional government itself. If not now, when? What impeachable offense could possibly outdo this one? Future presidents who commitment still high but nonetheless lesser crimes will be able to point to this as precedent. “I may have taken money under the table,” they will say, “but I never sent a mob to occupy the Capitol to hijack the counting of electoral ballots.” They will have a point.

Graham says pressing the case against Trump would amount to “political vengeance.” Actually, dignified retribution can in fact be just. Meting it out was Graham’s job as a military prosecutor. Impeachment, conviction and disqualification is not vengeance. It is prophylaxis.

Meanwhile, at National Review, John Yoo, fearing excessive prophylaxis that curbs presidential power, takes the split-the-baby approach to impeachment: the House was right to impeach, but the Senate should not convict. The basis of his argument is less prudential than formal.

Setting aside Yoo’s query about whether the constitutional text permits the trial of a former president–a legitimate question–the argument against conviction unfolds like this: As Hamilton says in Federalist 65, impeachment is a remedy for political, not literal, crimes. Trump, Yoo writes, “certainly committed impeachable acts,” including attempting to undo the election results and fiddling while the Capitol burned. However, conviction might weaken the presidency because it is the result of “a House impeachment process that took only two days.” A precedent for “abbreviated” impeachment proceedings might encourage the House to “seek to subordinate future presidents.” Moreover, “because of its hasty two-day proceedings,” the House “erred” in accusing Trump of “incitement,” of which Yoo says he is not criminally guilty. What was that about political crimes again?

Yoo’s first point had been correct: Trump is not accused of crimes but rather of “high crimes.” In the constitutional context, the reference to “misdemeanors” is also to “high misdemeanors,” a distinction evident in the articles of impeachment against Andrew Johnson, some of which accused him of “high crimes” and others of which referred to “high misdemeanors.” The constitutional use of “high crimes and misdemeanors” was a compromise at the Philadelphia Convention. George Mason had proposed “maladministration,” Madison objected to its vagueness, and the result was “high Crimes and Misdemeanors.”

But to Blackstone, “high misdemeanors” meant “the mal-administration of such high officers, as are in public trust and employment.” The effect of the compromise was to tie impeachment to an act or series of them rather than a general state of incompetence. Still, the key word remains that these crimes and misdemeanors are “high” ones, meaning their nature is political. Yoo, nodding to Federalist 65, seems to recognize all this, yet somehow wants Trump acquitted because he is not guilty of incitement in the sense in which criminal law uses the term.

Yoo’s real concern would appear to be weakening the presidency. Given that the office is swollen beyond recognition, we should be so lucky. Impeachment exists as a deterrent to bad presidential behavior and as a protection for the public against future high crimes and high misdemeanors–a fact the House recognized in noting, in the article of impeachment it passed this week, that Trump “will remain a threat to national security, democracy, and the Constitution if allowed to remain in office” (emphasis added). But deterrents only work if they are credible. They are not if no one believes they will be used even in the most extraordinary circumstances.

Stirring up a mob to a bodily attack on another branch of government in order to stay in office in violation of the Constitution–then refusing to protect the other branch even when implored to do so by its leaders–is, one can still hope, an extraordinary circumstance. “History will judge us harshly, as it should, if we do not rise to the occasion of this historic moment in our history,” Graham told Schumer in a sentence for which a professor of English composition would judge its writer harshly. But history is, in fact, watching. It is watching to see if impeachment is a dead letter. If conviction is not warranted here, is it possible to conjure a situation in which it would be?