Sailor Moon: Uranus and Neptune can't seem to get through their heads that choosing the more cynical options will only make the end results worse.
This is especially clear after Usagi became one of the targets of the Death Busters halfway through the third season, which meant Uranus and Neptune may have had to kill her if her pure heart held one of the talismans. After learning of her real identity, Haruka and Michiru haven't yet grasped that they were willing to kill the very girl whom they are trying to ensure will live long enough to become queen.
The Anti-Spirals of Tengen Toppa Gurren Lagann function on the belief that progress will always end in cosmic destruction. The heroes end up proving them wrong and destroy them instead.
Great Teacher Onizuka: Often a particularly jaded character (such like Urumi, Miyabi, Ms. Daimon...) will go in a rant about the rotting of the society, Adults Are Useless or abusive/perverted creeps, kids are delinquents, you can trust nobody or they shall abuse you or take advantage of you... Only for being told they are just blind cynics and that mindset is one of the roots of those troubles.
Onizuka went so far to tell Urumi her outlook is not logical. It is cowardly.
This appears to be a major theme in Naruto; the younger generation of ninja that Naruto belongs to, who move a great deal of the plot, are idealists, while the older ninja who lived through dark and violent times are cynics. However, the narrative frequently depicts the cynical views that peace is impossible and people can't understand each other as completely wrong, and the people who buy into this cynicism most are villains, some of whom are fallen idealists that turn around and help the heroes when Naruto or another challenges their cynical outlook. Nobody embodies this trope better than the Big Bad Duumvirate Madara and Obito Uchiha; both have completely given up on the world and plan to use Infinite Tsukuyomi to trap everyone in a "perfect" dream-world with them. Obito is clearly shown doing this because his life experiences have turned him into a nihilist that doesn't care about anything but leaving behind the reality he's come to hate so much, while Madara, the biggest cynic in the series, is also depicted as the biggest loser of all, talking about how much life sucks and how people are always destined to be losers as long as winners exist anywhere. Yahiko, Zetsu, and many of the readers see right through this to observe that Madara's spiel is mostly self-pitying Wangst about the misfortune Madara himself experienced in life, but is too proud to admit was almost entirely self-inflicted.
Danzo also embodied this mindset. Ultimately, he leaves behind a huge mess for everyone else to clean up while he utterly fails to accomplish anything.
Invoked in the final episode of Puella Magi Madoka Magica, by the main character, after Homura had espoused the opposite for much of the series. "If someone says it's wrong to hope, I will tell them that they're wrong every time. I could tell them that countless times."
Black Lagoon: Revy gets this from "the little maid" Fabiola at the end of the "El Baile de la Muerte" arc, but it's doubtful it had any effect.
In the German film Sterne, Walter, who is disillusioned both by his service on the Eastern front and by the treatment of prisoners in a nearby concentration camp, gets this response from Ruth, a Jewish woman, who eventually convinces him that even if he's powerless to put a stop to the evils around him, he can still make a difference - no matter how small.
The film-era Luke Skywalker pretty much walks away with this one. Han Solo disbelieves he can do much of anything on a galactic scale, only wanting enough cash to get Jabba off his tail. Obi-Wan and Yoda have written his dad off as a total, irredeemable loss. Luke matures over the course of the films, but doesn't ditch the idealism. He brings Han around first, and then proves his masters and the Emperor dead wrong about Anakin.
Bruce Wayne in The Dark Knight Rises isn't exactly a sunny optimist himself, but he never loses faith that cynical, hardbitten thief Selina Kyle can be a better person than she is, even after she betrays him, much to her incredulity. He's eventually proven right. In the previous film The Dark Knight, Bruce is also confident that the Joker's scheme to prove that deep down everyone is as ugly as him will fail. The people of Gotham prove him right in the end. And in the film before that Batman Begins, he totally rejects Ra's Al Ghul's belief that Gotham is beyond saving. By the end of the trilogy, Bruce is vindicated.
In Pride and Prejudice, Elizabeth's cynical outlook on life allows Wickham to completely dupe her about Darcy's true nature. The irony is that she acted this way in order to avoid being played for a fool, but it just happened in a different way.
In the Green Sky Trilogy, the cynical Neric tells Raamo that Genaa cannot be trusted and is too steeped in Ol-Zhaan privilege to be sympathetic to their plans. Not only does Neric turn out to be wrong, but Genaa turns out to be the one with the tactical savvy to pull off their scheme.
This is what happens to the dwarves at the end of Last Battle — they end up in Aslan's country with everybody else, but they're too cynical to believe it, and manage to delude themselves into believing they're still locked in a dark stable eating rotten food.
Somewhat common in Discworld, especially with Rincewind. The guy would be so obviously right in his cynicism...but Twoflower would come out fine anyway, leaving Rincewind looking like an idiot.
This is part of the entire point of Jean-Paul Sartre's No Exit. At the end of the story, it's implied that the main characters could leave at any time they wished to, but their own character flaws and lack of empathy with each other prevent them from doing so.
In Animorphs, the team cynic Marco notes this to Rachel while Jake is out of commission. They need a fast, straightforward plan for a high-risk rescue, and he explains that that's not his territory — his cynicism makes him too cautious to address that situation, so she needs to lead.
Oscar Wilde called a cynic 'a man who knows the price of everything and the value of nothing'.
Haroun and the Sea of Stories: Haroun's problem is that he has become so cynical he can't accept the reality of the sea of stories despite being beaten over the head with it. Pointed out by Blabbermouth.
"That's the problem with you sad city types. You think a place has to be boring and dull as ditch water before you accept it as real."
1632: In the Author's Notes of the first novel, this trope is all but named as the driving source for the tone of the series, as a response to the cynicism that had flooded the Sci-Fi genre at the time. Eric Flint specifically calls Cynicism weak and narrow-minded as a philosophy.
Justinia: Idealism is our stock in trade, Lambert. A religion without ideals is tyranny.
One of the main themes of The Lord of the Rings and Tolkien's Legendarium in general is the evils of cynicism and despair. Evil triumphs because people believe it can't be fought and give up (Denethor and initially Théoden) or join it (Saruman). The only way for good to triumph is fight for it, even if things look hopeless. And it's the acts of good by the smallest that end up saving Middle-Earth.
Unsurprisingly the other Star Trek shows are very big on this trope, even Deep Space Nine the darkest show has a number of episodes showing cynics as "do nothing but whine" while Idealist do something to fix the problem.
The Babylon 5 episode Intersections in Real Time focuses on a State Sec interrogator attempting to break Sheridan's will and join the xenophobic, totalitarian Clark regime. The interrogator consistently displays a very cynical outlook, stating that the preeminent truth of the time is that you can't fight City Hall, and tries to paint Sheridan's idealism as futile. Sheridan disagrees at every turn, remaining true to his ideals even in the face of grueling torture. At one point, he sums up his attitude by stating that all he has to do to win is to say "No, I won't," one more time than the people trying to oppress him can say "Yes, you will."
Learning this is essentially Jeff Winger's whole character arc on Community. He's a jaded ex-lawyer who, initially at least, honestly believes that everyone is selfish and out for themselves, the world is corrupt and other people only exist to be used to benefit you before being cast aside when you're done with them before they do the same to you. It's pretty clear, though, that his cynicism has left him lonely, miserable, and objectively speaking just as big a failure as everyone else at Greendale no matter how much he may disdain them.
Jeff: The truth is- the patheticly, stupidly, inconveniently obvious truth is- helping only ourselves is bad, and helping each other is good....Its that easy. You just stop thinking about what's best for you, and start thinking what's good for someone else. And you can change the whole game, with just one move.
In an episode of Bringing Up Daddy, Danny Thomas's oldest daughter has fallen for a Beatnik, and he and Danny end up having a fairly well-written argument about the beatnik's relentless cynicism just being an excuse to avoid doing anything about the social problems he's endlessly complaining about.
The Craig Ferguson quote at the top of the page is actually a summary of the main theme of Doctor Who. Indeed, the arc of the very first Doctor was that of a bitter old man realizing the importance of kindness and empathy. Since then, the main theme of the show is the triumph of these ideals, no matter how dark the world gets.
Fear Effect: Royce Glas is the cynical one. Hana Tzu-Vachel is the idealistic one. Glas is treated as the Butt Monkey and The Lancer. Hana is treated as the Iron Woobie and The Hero. It probably won't surprise you that the best ending in the first game essentially has Hana winning out without having to shoot Glas.
Final Fantasy VIII: Squall is a pretty great example of this. In fact, he seems aware that his dark attitude denies him opportunities for (what he thinks would be) brief moments of happiness, but he does it to avoid feeling further pain as a result of the loss of those moments.
In Mass Effect, the more cynical Renegade decisions the PC can make tend to go badly. Most notably, choosing to let the Council die in the first game ends with humanity being generally hated by the other races, while the human Council isn't even willing to meet with Shepard.
In Oracle of Tao, Ambrosia at the end of the First Disc (so to speak) heads off for the second world. Unless she bothered to do the romance sidequest (or can get past the Beef Gate of skipping a key romantic scene and heading directly through the entrance without stopping at the vacation town first), the plot requires you to visit Nevras at his castle. If you decide not to, or if you didn't get the memo, the story suddenly gets much darker, most notably in the endings. Basically, the point is, because Ambrosia decided her love life with Nevras was doomed, things got a whole lot worse for her.
Tales of Symphonia: It doesn't matter if the current system of how the world works has been used for 5,000 years or if prejudice and hatred prevents things from getting better. Lloyd will absolutely never stop believing that there's always a better way that can save everyone without somebody or an entire world needing to be sacrificed.
This is one of the recurring themes of the Lunar series: in the (remakes of the) first game, the villain is convinced that humanity needs the Goddess Althena to rule because people aren't capable of solving their own problems by themselves. Obviously, he's wrong. In the second game, it's mostly people on the hero's side (and a few Easily Forgiven villains for whom Defeat Means Friendship) that need to be convinced that Humans Are Special and they actually can go beat the crap out of the local God of Evil even though this should be impossible.
Gunnerkrigg Court in Chapter 29 has Paz, of all people, setting straight Kat (who is at that moment quite disenchanted with the Court after stumbling upon some of its old secrets).
Ian Starshine (and to a lesser extent, Haley as well — she veered off from this just in time) from The Order of the Stick. Choosing to remain in prison because you think your little girl is being hoodwinked by a calculating, nefarious, deeply undercover mole linked to an Evil Overlord(Elan?!? The Chaotic GoodCloud Cuckoolander?!? You're serious, right?) is this. In spades. Even having met the guy.
By repute, this was also the case for Properly Paranoid Girard Draketooth. Possibly. Rogue-like types are subject to this, it seems.
In RoommatesJavert of all people called out Disbelief on being too cynical by stating that even he wishes sometimes to believe.
It's Walky: Anti-HeroKnight Templar Sal, who is attempting to destroy every alien abductee in the United States (and, by extension, the entire continent itself) tells Joyce, the quirky, innocent goofy girl trying to stop her, that she's just a naive, deluded little girl. Joyce shoots back that Sal is the 'little girl'; Joyce has been through as many difficult and painful moments in her life as Sal has, but has matured enough to be able to cope with them without letting them poison her essential goodness and optimism, whereas Sal has been weak enough to let them corrupt her, and her reaction is the world-destroying equivalent of a childish attention-seeking temper tantrum. Sal has no comeback to that, and later events in the strip prove Joyce to be correct.
A common Armor-Piercing Question that sums up this trope is to say to the wangsty emokid "Why haven't you committed suicide yet?". In general, encouraging the cynic to question his own cynicism through a Socratic method is a better tactic in cognitive-behavioural therapy as a treatment for depression, instead of trying to disprove and mock it actively which simply results in encouraging the cynic to hate himself and trap himself in a vicious cycle of self-hatred. After all, true cynics are cynical about their cynicism, and if you go directly offensive on the cynic, you're just proving him right that you are Not So Different.
Though actually asking someone "Why haven't you committed suicide yet?" is reckless, dangerous, and unproductive. As decades of psychological, therapeutic, and counseling experience have proven, the question by its very nature is mocking and disrespectful, and an excellent way to lock someone into an even more cynical state of mind. Anyone actually considering suicide will probably have enough of a fatalist instinct to passive-aggressively take that as encouragement.
Jean-Paul Sartre, the key thinker of the movement, wrote that "Existence precedes essence." Basically, you are born, and then you are defined. You are what you make of yourself. If you are a villain, you were not doomed to villainy, your choices made you so. If you are a hero, you were not destined for greatness, it was the combination of your choices that made you that way. Under this philosophy, great heroism and great villainy are both possible by choice.
Conan O'Brien ended his run on The Tonight Show by asking people to please not be cynical, saying "It doesn't accomplish anything". Doubles as a Crowning Moment of Heartwarming.
"Remember, you cannot be both young and wise. Young people who pretend to be wise to the ways of the world are mostly just cynics. Cynicism masquerades as wisdom, but it is the farthest thing from it. Because cynics don’t learn anything. Because cynicism is a self-imposed blindness, a rejection of the world because we are afraid it will hurt us or disappoint us. Cynics always say no. But saying “yes” begins things. Saying “yes” is how things grow. Saying “yes” leads to knowledge. “Yes” is for young people. So for as long as you have the strength to, say “yes'.”
John Lennonmentioned in an interview that the reason he was first attracted to Yoko Ono was because he had been used to and indifferent to avant-garde art exhibits in The Sixties that veered towards cynical, negative, destructive messages, but Yoko's simple, direct exhibit, where one climbed a ladder, peered into a hole in the ceiling, and saw the word "Yes", was in John's opinion more valid in its positivity, hopefulness and affirmative message than the True Art Is Angsty approach other Sixties avant-garde artists took. It inspired the often naturally cynical Lennon (at the time suffering through a drug- and fame-aggravated Creator Breakdown) to see the other exhibits, and later to meet and befriend Yoko.
For all that Lennon himself tends to be viewed as the dark, cynical and 'deep' member of the Beatles — which, in the first two elements at least, is not an entirely unreasonable viewpoint to take — part of him clearly subscribed to this trope (or at least wasn't very happy being dark and cynical and wanted this trope to be true). For all his Creator Breakdowns and darker sides, anyone who describes the man who wrote "All You Need Is Love", "Imagine" and "Give Peace A Chance" as an irredeemable cynic is clearly overlooking something.