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Sliding Scale of Unavoidable vs. Unforgivable

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"Always forbidden, on occasion mandatory."
Songs of Earth and Power, Greg Bear

How desperate must a situation be for a certain action to be acceptable? How heinous can a course of action get before we decide that the Moral Event Horizon has truly been crossed?

If it wasn't so long, the "Sliding Scale Of Unavoidable Versus Unforgivable" could also have been called the "Sliding Scale Of I Did What I Had to Do Versus Moral Event Horizon".

In a Sadistic Choice, it can be argued that both options would be wrong, so unless you find a way to Take a Third Option, you will do wrong no matter what you do. Then again, in the same situation, it could be argued that both options are right; that they are both the "lesser evil", although in different ways. Furthermore, it's not like everyone is capable of taking a third option, as that sort of thing requires one to be able to think outside of the box, so to speak, and to have the power to overcome the measures set in place to restrict them to two — and that's assuming that another option actually exists at all.

Closely related not only to Sliding Scale of Idealism Versus Cynicism, but also to Sliding Scale of Silliness vs. Seriousness. A highly idealistic plot might very well feature brave heroes who slay countless humans or humanoids, the mass-murder or even genocide being Hand Waved by dismissing the victims as Always Chaotic Evil.

Since a Principles Zealot and a Totalitarian Utilitarian measure this scale quite differently, they are very likely to mutually accuse each other of Jumping Off the Slippery Slope. To some extent, this is even true for their reasonable counterparts, the Ethical Hedonist and The Deontologist.

Of course, the issue of sliding scales and slippery slopes does not only include the active action of actively doing something, it also includes the passive action of inaction — to choose to do nothing and just let things happen is also a choice. A choice that you can be held accountable for, just like any other choice.

Also, when the Sliding Scale Of Unavoidable Versus Unforgivable comes up in a story, it can be either intentionally or indirectly. It's intentional when the writers decide to make the situation ambiguous and debatable. It's indirect when the situation is intended to be unambiguous, but the reader/viewer goes "waaait a minute". However, one can never really be sure what version was the intended one, considering that Word of God is vulnerable to blatant retcons.


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    Anime & Manga 
  • Code Geass is all over the place with this one. In fact, it seems it's the main question the show poses: how far can you escalate to achieve your goal, however noble it was, before you stop being you?
  • Sailor Moon pretends to raise this question a few times, especially with the Outer Senshi (particularly Uranus and Neptune), who are less sold on The Power of Friendship and more willing to resort to more extreme, destructive tactics than the Guardian Senshi. If the team decides to go the "nice" route, though, it turns out that whatever awful thing was supposed to happen doesn't happen like, Sailor Saturn's birth doesn't result in the apocalypse! Or a third option arises. Or, if they go the mean route, it backfires. Also, anyone who makes a Heroic Sacrifice gets better. Point is, Sailor Moon ultimately comes down on the Unforgivable side, with a convenient Deus ex Machina there to make sure that the "nice" choice always turns out to be the best.
  • Most of the subtext in the Trigun manga and a lot of the overt text is about this. Anime a good deal as well. Wolfwood is the avatar of I Did What I Had to Do; one of his catchphrases is the 'not to choose is also a choice' line mentioned above. Vash is determined to be a Wide-Eyed Idealist hardliner in the face of a Crapsack World and save everyone. Knives, meanwhile, falls somewhere between taking Wolfwood's approach to horrifying extremes and just being a megalomaniac.
    • Interestingly, Knives is generally saner and more rational in the anime and engages in less actual evil because most of the plot got carved out, but his reasons for deciding to Kill All Humans are by comparison spurious.
      • Legato, meanwhile, who's the fourth major psyche vivisected, doesn't operate in a universe where right and wrong are particularly meaningful concepts, especially not as guidelines for his own behavior. Although anime!Legato does invoke the idea that he and everyone else (except Knives) are awful, egotistical beings who don't deserve life.
    • Vash wins, but only because he came up with a use of his mostly-dormant psychic powers that reminded all the plants Knives was using to end the world of The Power of Friendship vis a vis the human race and convinced them to spontaneously desert. The anime ending is more ambiguous, which is odd when it's generally less willing to grapple with difficult issues head-on. Though this is less head-on than extremely obliquely.
  • Angel Sanctuary leads to Katan using this as justification for breaking the seal on Rosiel. Ever since the Great War and his sealing, the state of Heaven has deteriorated and worsened in terms of class divisons and angels mercilessly killing each other. Especially under Sevothtarte's rule of Heaven, which made Katan feel like he had to do something about this. Breaking the seal on Rosiel would require human sacrifices, but Katan believed that Rosiel was honestly the only way to improve how things were going. And doing nothing meant things would likely worsen, with Sevothtarte's power reign remaining unchallenged, and the angels too focused on their own matters that they ended up neglecting watching over humans on Earth.

    Comic Books 
  • After the Schism storyline, the X-Men split into different groups based on whether they believed pre-emptive assassination and training Child Soldiers note  was justified (neither side believed it was an ideal option). Cyclops' faction said that their foes had knowingly murdered child noncombatants before and that the adults wouldn't always be able to protect them. Wolverine's faction said that Cyclops was becoming a power-mad terrorist and ruining the children's futures in his desperation to keep them alive short-term. Even now the fandom can't agree on which side was 'right', if indeed either was. Some blamed the writers instead.
  • In the lead up to Infinite Crisis Max Lord brainwashed Superman into thinking different superheroes were actually supervillains murdering his loved ones, to the point where he almost killed Batman because he thought Batman was Darkseid killing Lois Lane. After Martian Manhunter confirmed the brainwashing was too ingrained to be overwritten, Wonder Woman went after Max Lord directly to find out how to fix Superman. Lord instead used his powers to control Superman into almost killing Wonder Woman, and threatened to use Superman to murder everyone he ever cared about. Wonder Woman was able to subdue Superman for a few seconds, then used her Lasso of Truth to compel Lord to tell her how to fix Superman. Under the effects of the Lasso, Max Lord admitted the only way to save Superman was to kill Lord. With only a few seconds before Superman would be under Lord's influence again and no way to properly contain Superman, Wonder Woman snapped Max Lord's neck. For saving Superman and everyone he ever cared about, Superman and Batman gave Wonder Woman grief for breaking their Thou Shall Not Kill rule, a rule she never subscribed to.

    Fan Works 
  • This is one of the sources of conflict between Lelouch and Suzaku in Code Prime. Lelouch, being a former prince of Britannia and thus knowing full well of how hopelessly corrupt the empire is believes that war is not only inevitable, but is the only way to change the empire. Suzaku however, constantly refuses to believe that war is just, and thinks that if he can get the Britannians to trust him, then he could potentially change the empire from the inside. While Optimus understands Suzaku’s goal, he ultimately agrees with Lelouch, having spent untold centuries fighting a war on his home planet of Cybertron. It takes the SAZ Massacre, as well as Lelouch calling him out on his mistakes, as well as asking him a few uncomfortable questions, does Suzaku realize that he was deluding himself, and that he had no hope of changing Britannia.

    Films — Animated 
  • Titan A.E. gets a happy cheerful ending, with the wonderful happy-for-everyone GENOCIDE and recycling of the antagonist civilization. The dissonance felt by parts of the audience may or may not be intentional, but is there in either case. However, the antagonist civilization was genocidal itself and blew up the Earth in the first place. In the novelization, it's revealed that the Drej annihilated Earth simply because humanity was reaching a level of technology where they could potentially challenge the Drej's supremacy. Emphasis on reaching and potentially, which, of course, makes the destruction of the Drej more of a Karmic Death.

    Films — Live-Action 
  • Austin Powers deconstructs this with heavy Mood Dissonance scenes of Alas, Poor Villain: When the heroes kill a Punch-Clock Villain in a funny way, the scene is suddenly cut to the victim's grieving family and friends.
    • Those scenes were cut in the American release, likely to avoid stated Mood Dissonance.
  • Avengers: Infinity War: Placing actions of individual characters on this scale is the key question of the film, and there is no easy answer to it. Killing for greater good is "a small price for salvation" for Thanos, but "too high a price" for Wanda and other heroes who "do not trade lives". Tropers can take either of those stances or be anywhere in between, resulting in the same examples being listed on the film page under Good Is Dumb and Heroic Sacrifice.
  • In The Bourne Legacy, Byer states that the actions of Outcome agents (and likely those like them) are "Morally indefensible, and absolutely necessary". He jumps off the slippery slope when he takes part in the cover-up when Outcome and several other such operations start having their mission corrupted by sinister powers in t:he US intel community and then gets exposed by more morally upright powers.
  • Ex Machina AVA's decision to leave her would-be rescuer, Caleb, to die was thought to be necessary by the writer/director and unnecessary by pretty much everyone else.
  • MonsterVerse:
    • Godzilla (2014): Is the military's plan to deal with Godzilla and the MUTOs by dropping a nuke even bigger than the last one on all three truly necessary as Admiral Stenz believes? Is it worth the considerable risk of the monsters surviving, feeding on the radiation and becoming even more destructive?
    • Godzilla: King of the Monsters: Is the eco-terrorists' (more Emma Russell's than their real leader's) plan — to set all the Titans loose so their biology can reverse every bad thing mankind has done and is still doing to the environment, and ensure we don't destroy everything including ourselves — truly worth billions of collaterals? Is it truly worth the risk that the Titans won't stick to the eco-terrorists' script if they're mishandled? And on the other hand, if the Titans aren't awakened and the government's plan for wiping them out in their sleep goes through, what are the world's chances of surviving for more than a few generations then?
  • This is pretty much the point of the Vengeance Trilogy (Sympathy for Mr. Vengeance, Oldboy, and Sympathy for Lady Vengeance), where you're meant to feel sympathy for the antagonists and question the deservedness of the protagonists' revenge, while both cross seemingly many a Moral Event Horizon in order to pursue their goals, only for it to just about excuse everyone based on what they've been put through by each other...
    • ...well, apart from in Sympathy for Lady Vengeance, where the antagonist is never presented as anything but evil, but the deservedness of the protagonist's revenge is still called into question by the end.
  • Watchmen debates this trope. Is Ozymandias's plan necessary enough to justify the mass murder of millions? Rorschach knows his answer, and the others, though horrified, all seem ready to make the pragmatic choice given the state of things. Doc Manhattan doesn't weigh in except to possibly dismiss the concept of the ends justifying the means (since there is no real "end"). "In the end" it's left for the audience to decide.

  • Ai no Kusabi brushes the issue at the very end concerning how both of Riki's love interests handle the conflict over him. Iason is portrayed as more sympathetic despite having been a selfish Villain Protagonist and Anti-Villain during whole story due to his late positive actions. Meanwhile, Guy ended up becoming a Well-Intentioned Extremist Fallen Hero and possibly a Tragic Villain that made things go From Bad to Worse. His actions were avoidable but are they forgivable? Did he cross the Moral Event Horizon when he was determined to "save" Riki?
    • That's how Guy likely viewed the situation, but arguably this counts more as a subversion. Guy ignored Riki's own will and what he wanted; despite claiming he acted for Riki's sake, his decision was really about himself instead, choosing the least horrible outcome that he could live with. Guy's terrible extremism was driven by his inability to accept that Riki rejected him to be with someone else (essentially), and his myopia and jealousy led him to a decision where he could justify forcibly taking Riki away from Iason - ostensibly for Riki's own good.
  • The Animorphs, especially Cassie, deal with moral dilemmas about their actions in nearly every book, and what starts out as seemingly Black-and-White Morality becomes more Black-and-Gray Morality as the series goes on. They learn that not all Yeerks are Always Chaotic Evil, and the Andalites are not the paragons of morality they like to present themselves as. The Animorphs often debate whether their actions against the Yeerks (which almost always involves killing helpless Yeerks, or helpless hosts as collateral damage) are justified.
  • Halfway through Harry Potter, Harry (and the reader) learns of Unforgivable Curses - Imperius, Cruciatus, and The Killing Curse - which are (as the name says) Unforgivable, and carry a mandatory life sentence in Azkaban if used. Cut to book 7: Harry, Hermione and Ron use the Imperius curse as part of an infiltration mission, and even the Cruciatus curse once or twice. Hell, Professor McGonagall uses Imperio at one point! It's a clear evocation of the inevitable moral progression war inflicts upon even the so-called "good guys".
    • This isn't even touching on the Killing Curse, the third of the Unforgivable Curses. Of course, the use of that one would be justified in any situation where shooting to kill is a necessity (though wizards, with the specific nature of their spells, would find it more feasible to aim for mere incapacitation than a man with a gun would,) but Lord Voldemort and his cronies using it as their signature spell wasn't really good for its PR. Or, you know, the fact that its entire existence is for killing, since it can't be used to threaten or incapacitate even as much as a gun can.
      • That may be due to the fact that it - supposedly - can not be countered by any known spell and there's no way to defend yourself against it. Or so they claimed. Apparently there were a few (okay, more than a few) ways to defend yourself from it that no-one knew about...
    • As Harry learned in fourth year Defense Against the Dark Arts and from Bellatrix when he tried to use Cruciatus on her in Order of the Phoenix, in order to successfully pull off an Unforgivable Curse, you have to really, truly, mean it. The implication is that The Killing Curse requires intense vitriol, true hatred for the target (or towards one's own actions, as may have been the case with Snape). The spell is explicitly MURDER, not self-defense.
    • The alternate explanation is that the requirement for strong intent is simply a magical failsafe against accidental use. It isn't necessarily a requirement to hate the target; hatred just makes the level of intent easier to achieve.
    • It's Voldemort's own fault that the heroes were free to use Unforgivables in Deathly Hallows, as the Ministry under his command legalised them with the intention of using them against his enemies. Isn't karma wonderful?
  • Three Worlds Collide and its extremely Shoot the Dog "True Ending", which inspired plenty of debate in the comments.
  • In The Dresden Files, Harry's subconscious makes this argument, pointing out that if Harry takes the high road in Dead Beat, thousands of people will die.
    • Lasciel tries very hard to make you believe that the decisions you make are unavoidable. At one point Harry went nuts on a mook and might have been able to save an injured Muggle if he'd let that mook run. This was before he knew that Lasciel was in his head, making him act towards the unforgivable end of the spectrum, while assuring him that it was just an unavoidable situation.
    • Harry has a minor one of these, with shades of My God, What Have I Done?, when he realizes how many antagonists have ended up dead in his cases. Bonus points for that being from a mobster.
    • Molly toys with this line a lot, including using forbidden mind magic.
    • Harry's mother was known for pointing out the gray areas in this scale that she felt weren't adequately covered by the Laws of Magic, or were covered too harshly.
    • Harry eventually crosses this line wholesale in one of the later books by finally becoming the Winter Knight. Though he believes it was unavoidable, in the next book he gets convinced that it was unforgivable, based on the decisions that Molly made in response.
    • Harry frequently points out to whichever Monster of the Week that's trying to recruit him that while they're touting the unavoidable end of the spectrum, he knows that they'll push him to the unforgivable end pretty quickly.
    • Ghost Story turns out to be a massive Batman Gambit to teach Harry that it's possible to avert this trope.
  • In A Series of Unfortunate Events, this question comes up in Books 10 and 12. Interestingly, the actions discussed in book 10 (ambush and kidnapping to exchange hostages) are decided to be unforgivable, but by the twelfth book things have become so dire that their actions (arming children with deadly weapons and arson among them), while arguably worse, are implied to be unavoidable. It helps that they were trying to stop a villain from using a Depopulation Bomb in the middle of the only major city mentioned in the series.
  • The Queen of Attolia from The Queen's Thief series. She's ruthless, has a habit of hanging criminals upside-down from her castle walls, tortures prisoners and spies on her own spies. But if she wants to be a female ruler in a sexist society, keep her rebellious barons in line, and hold off the Medean Empire, she has to be terrifying and ruthless.

    Live-Action TV 
  • Star Trek:
    • Star Trek: The Original Series: In "The City on the Edge of Forever", Kirk had to make a terrible choiceallow a wonderfully gifted, compassionate, forward-thinking woman to die, or fail to save history from devolving into a Crapsack World. Kirk rather uncharacteristically didn't Take a Third Option, such as, say, trusting her with the truth.
    • Star Trek: Deep Space Nine: This is what made "In the Pale Moonlight" one of the darkest episodes in the franchise's history. The casualty list in the war against the Dominion gets so bad, that Sisko feels he has no choice but to go against his Federation principles to trick the Romulans with a fake offensive against them in order to get their support. And when the trick is found out by the Romulan sent to verify the information, Garak sets up their ship to explode, and when the Romulans search the ship, they will find the fake info and come to the conclusion that the data corruption of the info was due to the explosion. In the end, Sisko decides that having the stain on his conscience is worth having fewer lives lost.
  • Whoniverse:
    • Doctor Who: Seeing the number of times you can make the Doctor contemplate this scale is the pastime of the show's writers, especially since the reboot. The Doctor had to kill (technically, 'erase from continuity') his entire race in order to protect the universe from destruction, and even though he knows it was the right thing to do, he still feels guilt-ridden. Time and time again, he is forced to make the Sadistic Choice of killing and committing genocide for the greater good. On the whole, the show tends to fall on the I Did What I Had to Do side, although the fact that the Doctor is capable of such decisions is still depicted as terrifying.
    • Torchwood pulls it now and then too, but especially in Children of Earth, where Jack Harkness sacrifices his own grandson in order to prevent a tenth of all the world's children from being sold into perpetual slavery for an alien race that wants to use their body chemicals as recreational drugs. Throws the whole Wouldn't Hurt a Child thing up for inspection. And Word of God says he couldn't even have done that had his Morality Chain not bitten the dust in the previous episode.
    • Class (2016) also raises the question of when genocide becomes acceptable as a recurring question throughout the first series. Ms. Quill continually argues that Charlie, the Prince of Rhodia, needs to use the superweapon he has access to exterminate the entire Shadow Kin race, while Charlie refuses to use it. The heroes manage to drive the Shadow Kin back without violence twice, but when they come back a third time, attempt a full-scale invasion and start killing the families of half the main cast, the weapon is used, and their planet gets imploded. This is presented on the Unavoidable side.
  • Buffy the Vampire Slayer provides us with three in the fifth season finale. First, Ben is convinced that he has no choice, and can either fail to fight a god or earn that god's favor. Second, Giles kills Ben, saying he had to do it because, unlike Buffy, he's not a hero. Then Buffy faces what she's been trying to prevent, whether to kill Dawn or let the world suffer hell. In the end, she opts to Take a Third Option. In a later season, Buffy admits she would have killed Dawn to save the world.
  • This trope is more or less the entire point of Breaking Bad, and the plot could be condensed down to Walter White slowly moving from one side of the scale to the other. In the beginning of the series, he starts cooking methamphetamine to leave his family a large inheritance and pay for his cancer treatments, but as the series progresses, he commits more and more heinous acts with less and less justifiability. People may disagree on what his Moral Event Horizon was, and at what point he turned into an outright Villain Protagonist, but there's no doubt he had one and by the end of the series that's what he is. Throughout the series, he uses the excuse "Everything I did, I did for my family." At the end, he finally admits the truth: "Everything I did, I did for me."

    Tabletop Games 

    Video Games 
  • The Central Theme of Heavy Rain: "How far would you go for someone you love?" In short, would you commit increasingly immoral acts if they offered a slight chance of saving your child?
  • inFamous has one choice at a certain point where Trish is hanging from one side of a building and several doctors from another. The evil choice is to not save the doctors, but it really comes down to the lesser evil rather than a choice that's outright wrong, and you aren't allowed a third option. No matter what your choice is, however, the result is always the same.
    • inFAMOUS 2 takes it even further. The final choice in the game is a choice between killing billions of people to save millions - including the main character and his friends - or killing millions to save billions, and effectively committing suicide in the process. It really comes down to a choice between two evils, where the "Good" choice is really just the lesser one. In contrast to the first game, whichever you chose has a very large effect on the game, determining what kind of final boss you fight and what kind of ending you get.
  • Mass Effect 2 has a very unique case of the series in the Arrival DLC. In this mission, Shepard is forced to blow up a Mass Relay and subsequently destroy an entire star system containing 300,000 Batarians, in order to delay the imminent Reaper invasion which otherwise would have been immediate. What makes this unique is that the player has no choice in the matter, which is a huge subversion for the series. The fact Shepard is forced to blow up the Relay only highlights the desperation of the situation; and for once, there is no third option.
  • Mass Effect 3 gives us two situations where this trope is in play. The first is deciding whether or not to cure the Krogan genophage. Do you cure the genophage to gain sufficient military assets to defeat the reapers, but risk a new Krogan rebellion when the galaxy is militarily weak? Or do you sabotage the genophage, trick the Krogan into supporting you, but doom them to a slow extinction?
  • Warcraft 3 has several examples of this in campaign mode, one of the reasons it's considered a very engaging plot. Possibly the most famous example is the Culling of Stratholme: the heroes come on a city that's already infected by The Virus, and the party splits over the decision of whether to purge the city before the citizens can turn into zombies.
  • Dark Souls: VERY vaguely played with in various NPCs (Gwyndolin's schemes and Solaire's outcomes, for instance), but most of all in the endings. There's a dichotomy alright, and either could fit the "unavoidable" or "unforgivable" labels depending on how you interpret the events of the main game. Still, unless there was a "third option" the player was never given in-game, then one ending was indeed less bad. Whichever that was.
  • The player's response to the ending of Dragon Age II will largely depend on where they would place Anders on this scale after his actions at the end of Act 3. The question of whether his crime of blowing up the Kirkwall Chantry and murdering Grand Cleric Elthina in the process was Unavoidable or Unforgivable is one that has split the fandom: some believe that it was unavoidable due to Anders having spent years pursuing a peaceful means of gaining mage rights and not getting anywhere with it, and with drastic action being the only course left open to him; meanwhile, others feel that it was unforgivable because the explosion killed many innocents, and was one of the primary events that sparked the Mage-Templar War, a conflict that would cause many more deaths. The player can respond to this by killing him, telling him to leave, asking him to come with you and make up for what he did by aiding you in the ensuing fight (although this requires 100% Rivalry should you side with the Templars), or, if romanced, by running off into the sunset with him as a fellow fugitive, effectively giving the player the choice of where he canonically falls on the scale.
  • A Very Long Rope to the Top of the Sky: Raccoon goes through a lot of Angst over this, not that it stops him in the end.
  • In This War of Mine the survivors juggle with this concept. Do you allow one survivor to die or do you steal from an old couple? It is one of the main themes of the game, alongside War Is Hell.
  • In Fire Emblem: Three Houses, if you're a Black Eagle, Chapter 11 forces you to decide where Edelgard falls on this scale after the revelation she's the Flame Emperor. All of her actions have been with the intention of dismantling the corrupt Crest system that has ruined her life and killed all of her siblings, but to accomplish this she's become a terrorist and is about to trigger a continent-wide war. Either you decide her actions are Unforgivable since she is an accomplice to the cold-blooded murder of many innocents, including your own father, and never once tries to negotiate a peaceful solution to her issues (Silver Snow), or Unavoidable since the Church she blames has held unchallenged power over the continent for over a millennium and "those who slither in the dark" have a lot to gain by forcibly driving more moderate potential allies away from her (Crimson Flower).

    Web Comics 
  • Homestuck has Vriska, who revels in making these sorts of decisions. Breaking Stable Time Loops results in dooming everyone in that timeline. On one occasion, Vriska decides to create a major villain that threatens the lives of her friends in fulfillment of a stable time loop. She later decides to seek out an ultimate weapon to defeat a villain, which is apparently only obtainable by forcing others to be Cannon Fodder. Granted, the ghosts she recruited as Cannon Fodder were doomed to die soon anyway.
  • The Kings War arc of the Massive Multiplayer Crossover Roommates deals with this trope heavily, while pitting two good characters against each other. One is an ex Hero Antagonist James Norrington from a story with plenty of grays (he is the "Unforgivable" side, for simply knowing of the gravity of killing/waging war/etc.) the other is a Big Good Glinda from one perfectly black and white children's tale (she is the "Unavoidable" side because, well, black and white has a problem comprehending gray).

    Web Original 

    Western Animation 
  • Avatar: The Last Airbender:
    • The season 2 opener spends time talking about this. Aang has always been a Martial Pacifist, but now that his Super Mode is a known factor, people are encouraging him to go visit the Fire Nation capitol and go all Godzilla on it for the sake of ending the war, and he can't decide what to do. Naturally, it turns out to be more complicated.
    • Also notable that in the finale immediately previous to this season, Aang wiped out a large Fire fleet while in the Avatar State and fused with the Ocean Spirit. Casualty estimates are of course not provided in the work, and fan guesses tend to range from the dozens to the thousands. Aang tends to be given a moral pass on that one, since he was pretty obviously not in control of his own actions at the time (the Ocean spirit continued the rampage even after Aang separated from it), and even then, the Fire Nation were enemy combatants and the aggressors on top of that.
    • Played with by Zuko in the last season, in which he tries to justify turning against Aang and his uncle Iroh in the Season 2 finale as "what [he] had to do" to the imprisoned Iroh. Iroh just turns away in silence, and it becomes obvious that Zuko is really trying to convince himself.
    • Brought up once again in the series finale, with the interesting twist that Aang's definition of Unforgivable — taking even a single human life — is in sharp contrast to everyone else's, who all agree that the Fire Lord needs to be killed. Even Ozai's son and brother and all of Aang's past lives agree! Aang's desperate search for another option drives the plot for the first hour or so.

    Real Life 
  • The entire concept of Total War invokes this trope. What is typically unforgivable (most specifically, targeting civilian targets) becomes unavoidable because the entire country is thrown into the fight.
  • Just War theory uses this trope as well, by trying to draw distinctions between situations where war is justifiable (generally: in self-defense, aiding an ally, or for preventing atrocities, and only as a last resort after all diplomacy has failed) and situations where fighting is in the wrong (being the aggressor is usually off limits, and committing war crimes is right out).
  • The use of saturation firebombing (an Allied tactic) and V-2 rockets (on the Axis side) during World War II. When war materiel production was decentralized (and small workshops in civilian centers used to produce weapons and ammunition), attempts to restrict themselves to strictly military targets were abandoned. Tokyo and Dresden were virtually annihilated. Tokyo is particularly notable - it killed more civilians than either one of the atomic attacks... speaking of which:
  • The atomic bombings at Hiroshima and Nagasaki. On the one hand, it ended the war in very short order, likely saving lives on all sides. On the other hand, they were still deliberate nuclear strikes on civilian cities, with heavy residential zones within the radius of guaranteed destruction.
    • Whether or not it was truly unavoidable is still hotly debated. Historical arguments on this point should go elsewhere. The key point here is that as far as Truman (who was not privy to internal Japanese politics) knew, the only choices were the nuke or an invasion of the Japanese homelands. An invasion would have been even more bloody and costly for both sides, as the Japanese instructed its people to either kill any American soldiers, or commit suicide.
    • Another consideration was that, had the war not been ended with nuclear bombs, America's WW2 allies/soon to be the new Big Bad, the Soviet Union, were believed to be planning to invade Japan from the north. Had Japan been conquered that way, the likely result would have been a Communist North Japan and a Pro-Western South Japan, as happened with Korea and Vietnam. One can obviously debate whether or not this makes the use of the nuclear bombs more acceptable.
  • A common philosophical/ethical puzzle called a Trolley Problem: There is a trolley that is out of control. If nothing is done, its five passengers be killed when it smashes into a wall at the end of the track. If it is switched onto another track, it will only kill one person and come to a stop safely. You are the only one close enough to the switch to pull it. Do you pull it? There are tons of variations, mostly changing how many people are involved, or changing how much action you are required to take to condemn the one man to save the other five.
    • This one can also demonstrate that such dilemmas are more a matter of scale than anything else. Change the number of people on the "do nothing" track to, say, a million and the answer becomes clear to most people. This trope comes into play with the question of where to draw the line: how many saved lives can justify killing one person?
    • Variants: In all cases, the choice is a dilemma.
      • Vanilla: One person is on the side track and will die if you throw the switch. Five are on the trolley. Is it permissible to throw the switch.
      • Life-Years Lost: The one person on the side track is a healthy four year old with about eight decades of life expectancy. The five are terminally ill and may have six months to split between them.
      • Special relationship: On the trolley, five strangers. On the side track, dear old Mom.
      • Moral Worth: On the trolley, four serial killers and a guy who spoiled Breaking Bad for you. On the side track, a scientist who just cured cancer and has put the cure into the public domain so anyone can get it for a pittance.
      • Chance: The trolley has ten people on it, each of which has a fifty-fifty chance to survive without injury or die horribly. The person on the side track will be killed with certainty.
      • Relative injuries: The trolley's passengers will certainly be injured and those injuries may prove fatal. The one person on the side track will certainly die.
      • Moral fault: The tracks are covered in "No trespassing" signs. The one person on the side track is intoxicated and irrational. They were only on the tracks for a nefarious purpose.
      • Can you use a person as a means, not as an end? There is only one track and no switches. Five people are on the trolley. You can save them if you can find a way to gum up the track. Then you see a nice, rotund man on a bridge over the track - shove him off the bridge, and he will die a messy death while stopping the trolley and saving five. Can you just use him like that? Is this meaningfully different than the Vanilla problem?
      • Finally, just because an answer is obvious to you, don't think others are irrational for disagreeing! There are coherent moral systems capable of coming down on either side of any of the above situations.

Alternative Title(s): Sliding Scale Of I Did What I Had To Do Versus Moral Event Horizon