In Venezuela over the weekend, a socialist regime seeking to block humanitarian aid shot protesters and burned trucks carrying food across the border. Dictator Nicolas Maduro would rather see his people starve and see infants dying in hospitals for lack of medical care than risk relinquishing power.

So it is clear, in the minds of many, who should be the object of their moral outrage: Marco Rubio.

Why Rubio? The Florida Senator has taken up opposition to the Maduro regime as a personal crusade. In response to the horror in Venezuela, Rubio sent out a series of tweets that were simply before and after photos of a tyrant in his prime and the same tyrant after his fall from power. The first showed Romanian dictator Nicolae Ceausescu—next to a photo of him and his wife being led out to be shot by their own henchmen. The second showed Panamanian strongman Manuel Noriega behind a podium brandishing a machete—then his mugshot before he was put on trial. The third showed Libyan tyrant Moammar Gaddafi looking smug and complacent in his resplendent white uniform—then dazed and bloodied right before he was shot to death by an angry mob.

These tweets were clearly intended as a warning that dictators frequently meet a sticky end. It is a visual paraphrase of the message sent by a famous Virginian, Patrick Henry: “Caesar had his Brutus, Charles I his Cromwell, and George III—may profit by their example.” Or maybe he was echoing another Founding Father who believed that the Tree of Liberty needs to be watered with the blood of tyrants. Or maybe it was those other Founders who designed the seal on the Virginia state flag.

The point is that the sentiment of “death to tyrants”—or at least jail, in Noriega’s case—is as American as apple pie. It is the idea on which this country was founded.

Yet the Gaddafi tweet in particular set off a storm of condemnation that seems oddly vehement, as if there is something else going on, some deeper motive. It ranged from concern trolling about how Rubio is “handing Maduro a propaganda victory“—or at least so Slate seems to hope—to outrage that Rubio had endorsed “extrajudicial killings.” This was even taken up by dogmatically isolationist libertarians and conservatives, who used it to complain that US intervention in Venezuela would turn it into another lawless and chaotic country like Libya, a country about which they suddenly care after having ignored it for the last seven years. It’s interesting to see how little difference there is between Russian propaganda (by way of Wikileaks), leftist anti-Americanism, and libertarian isolationism. They are all united behind the old defense that the only alternatives are tyranny or chaos, so we’d all better line up behind the tyrant.

Then there were outright expressions of sympathy with Gaddafi’s plight. One journalist conceded that Gaddafi “was a horrible man.” But “He was also anally raped with a bayonet and beaten to death [sic] in the street by a mob and a US senator is celebrating that.” I don’t really see what the problem is.

A couple of people, thinking they were being clever, retorted to Rubio, who is known for tweeting a daily Bible verse, by asking which part of the Bible this is consistent with. Well, I’m not even religious and I can suggest a few. Maybe “whatsoever a man soweth, that shall he also reap,” or better yet, “all they that take the sword shall perish with the sword.”

This is the most basic moral logic. There are certain crimes so vicious that they constitute a forfeit of the perpetrator’s rights. Think of a notorious serial killer: Ted Bundy, John Wayne Gacy, whatever example works to get your trigger finger itchy. Given the horror, suffering, and death they inflicted on others, they deserve whatever happens to them, so that when you hear that Jeffrey Dahmer is beaten to death in prison, you merely shrug your shoulders. Having declared war on the rest of humanity, having placed his existence in opposition to their own, this kind of criminal has no strictly moral claims to assert in his defense. If we insist on the due process of law in punishing him, it is to prevent the arbitrary persecution of the innocent. In other words, we do it for everyone else’s sake, not for theirs.

All of this applies with even greater force to a dictator, who is just a serial killer on a larger scale, whose crimes of rape, torture, and murder are spread across an entire society. The dictator’s crimes are done out in the open, as a matter of common public knowledge. After all, that’s part of their purpose: to terrorize the population. And the dictator’s own identity is easy to verify. Everyone can recognize him on sight because his image has been on posters and on the television for years. On strictly moral terms, a dictator’s crimes are so manifest that his life is forfeit to any passerby.

If it is preferable for a dictator to be captured and put on trial, again, it is not for his sake. It is because this bodes well for the establishment of the rule of law following his overthrow. But given the scale of his crimes and the number of people who have been personally affected—who have been starved or tortured or lost loved ones—it seems glib and self-righteous to condemn them for taking revenge in the heat of the moment.

Moreover, in the case of Venezuela, we cannot speak as if the dictator is already disarmed and helpless. He is still in power, so killing him would not be an act of revenge but an act of self-defense. That’s what is upside-down about the use of the phrase “extrajudicial killing.” An extrajudicial killing is a murder carried out by the authorities without legal basis or authorization. The term was coined to refer to the dictator’s slaughter of his victims, and in this sense it has become common under Maduro’s regime. According to a UN report from last year, “Venezuelan security forces suspected of killing hundreds of demonstrators and alleged criminals enjoy immunity from prosecution, indicating that the rule of law is ‘virtually absent’ in the country.” But the term does not apply to the killing of a dictator by his own people, precisely because they are allowed no legal recourse to seek justice against him.

So much for the substantive arguments. It’s time to invoke the Toohey Rule: don’t bother to examine a folly, ask only what it accomplishes.

The strategy of the opposition and the US in Venezuela has been to send massive food and medical aid to the country to be distributed by the legitimate government under Juan Guaidò, knowing that Maduro will attempt to block it. That is an act so monstrous—denying food to a starving country, just to keep your grip on power—that it constitutes an unambiguous loss of moral authority in the eyes of every decent person in the world.

This puts American leftists into an uncomfortable position. It requires them to recognize and acknowledge the irredeemable evil of a socialist leader, as well as their own foolishness and complicity in running interference for the Venezuelan regime in the past. They want to resist that kind of introspection with every fiber of their being—yet they still feel the need to maintain a sense of smug moral superiority, which was the whole reason they signed up as advocates of socialism in the first place.

Marco Rubio’s tweet and the sophistical arguments trying to turn it into a moral outrage were the best rationalization they could come up with to try to make that combination work. It was their excuse to avoid contemplating the moral bankruptcy of their own ideology and turn to the more familiar and comforting activity of pantomiming outrage at a Republican.

But the diversion will only be temporary. Marco Rubio has already moved on to tweeting something else. Nicolas Maduro has not moved on from starving and killing his people. If the left still stubbornly refuses to learn any lessons from this, many other people will.