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Perfect Solution Fallacy

"Perfection is the enemy of the good."
Voltaire

Also Called:

• Binary thinking
• Nirvana Fallacy

A subcategory of False Dichotomy, the Perfect Solution Fallacy is arguing that a course of action is no good because it is not perfect. This essentially assumes the opposite of the Golden Mean Fallacy; rather than assuming the extremes cannot exist and the middle is correct, it assumes the middle cannot exist and a solution is either absolutely perfect or entirely undesirable. This is then used to argue that the hypothetical perfect solution must be used, or that a solution is useless because some part of the problem will remain after it has been implemented.

Using reusable bags instead of paper or plastic will help the environment.
However, the ideal solution would be for nobody to use bags at all.
Therefore, since it isn't the best possible single solution, it isn't worth doing at all.

Since outside of mathematics a perfect solution to anything is unlikely in the extreme, this fallacy is usually combined with Begging the Question; a debater will assume a "perfect" solution is one which fits his argument and ideals, regardless of whether his opponent would view the result as perfect or even desirable.

A sneakier form is to not state what the idealised solution actually is, and instead dismiss a position purely because it has flaws at all:

Reusable bags require raw materials, manufacturing, fossil fuel consumption, shipping costs, (and so on).
These flaws clearly show it is not a worthwhile solution.

This will often incorporate "flaws" which are also flaws of the system that would remain if the solution were rejected. This is often the basis of an Appeal to Ignorance; the claim then is that because we don't perfectly understand something, our theories about it are necessarily false, no matter how good the models they generate are.

This fallacy is the basis of the proverbial admonition, "Don't let the perfect be the enemy of the good." The inverse is to argue that something is a good course of action simply because it is "better than nothing," without explaining why it is better than nothing.

Looks like this fallacy but is not:

• Assuming an opponent wants a perfect solution through use of a Slippery Slope / Hasty Generalisation Fallacy: for example, an opponent claims that minor things X, Y and Z in a videogame are unrealistic, and gets the response "well if it were really realistic you would only get to die once!"
• Rejecting a solution due to comparison to a concrete and achievable state which is argued to be superior. Rejecting a proposal to eat cold food when you are in a room which has a stove and you have time to cook it is not a perfect solution fallacy. Rejecting a proposal to eat cold food when you are in an ice cave at the North Pole with no method of starting a fire, on the other hand, is.
• Begging the Question applies here heavily: your opponent must agree that the state in question is concrete and achievable for you to be able to use this as a premise.
• Rejecting a solution which actually does prevent one agreed to be better from being implemented.
• Rejecting a solution based on a comparison to the status quo, such as a cost-to-benefit ratio. The fallacy is only committed when one side rejects a solution because it is inferior to an idealised one, not when they reject it because it is inferior to an existing one.
• Rejecting the presentation of something as an alternative to the current course of action when it is only actually suited as a complement to it; in this instance, the inability to provide 100% replacement means it cannot be regarded as an alternative. For example, "alternative" electrical sources are not capable of providing 100% of a country's energy needs, and therefore cannot be accurately described as an alternative to more conventional generating methods.

Examples:

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Comic Books

Fanfics
• As far as Knowledge Is Power is concerned, the fact that Dumbledore's plan to defeat Voldemort had some flaws makes him as evil as Voldemort himself.
• In the Miraculous Ladybug fic How Not To Propose, Adrien refuses to propose to his girlfriend because he wants the moment to be absolutely perfect when he does: scenery, food, music, everything. Naturally, the universe conspires to ruin all his attempts at setting up such a moment, and Adrien's inability to compromise ends up prolonging the situation so badly that Adrien's girlfriend begins to wonder if he's serious about their relationship at all.
Plagg: Adrien! You have to be kidding me! That was the third custom jeweler we visited. Do you even know what you want?

Internet
• This is popular when answering a technical question on the internet: "There is no solution to your problem which I can guarantee to work in 100% of all cases. So I'm not going to bother telling you what will work in 99% of all cases."
• Also common is ignoring the stated problem on the grounds that the questioner has in his or her ignorance already failed to follow a "perfect" approach or methodology and should never have come upon that question in the first place. In other words: "I won't give you the solution you're asking for, because the knowledge would clutter your mind. You should instead try to solve this problem, which will allow a more perfect solution." Especially annoying as while the odds are good responses of this type will satisfy the original questioner's needs and thus end the dialogue, there's bound to be somebody else who's already familiar with the issues, genuinely does need an answer to the question, and now has unhelpful nonanswers cluttering the search space.
• You will hear this combined with Poisoning the Well if you hang around a review site for any length of time; always in defence of something the poster likes that scored poorly. "Well, reviewer A might say that about game Z, but reviewer A scored game Y too high / low, so obviously this site is not trustworthy." The implication is that because the site's reviews are not perfect, they are worthless.
• Commonly used to refute the reliability of wikis, usually The Other Wiki. The fact that there's no way to permanently protect every single page from all vandalism or absolutely confirm that every last sentence added in good faith is absolutely true over all scenarios, becomes an excuse to claim the wiki is always wrong.

Live-Action TV
• Used in several episodes of Penn & Teller: Bullshit!. When discussing the American Disabilities Act, P&T take a man and his iron lung for a walk through town, noting several ADA-compliant shops and facilities that cannot accommodate him. No matter what accommodations a business implements, they state, somebody will always be left out, so why should the government be allowed to set and enforce an arbitrary standard?
• An episode of The Daily Show lampooned a group of Fox News personalities who claimed that a proposed tax increase on the super-rich was worthless in eliminating the federal debt because it would generate "only" an additional \$700 billion over 10 years, a small fraction of the overall debt. (Stewart and Co. then went on to show that raising taxes on the lowest-earning 50% of the population could only generate the same amount by claiming HALF of all of their material wealth in taxes.)
• A meta-example in a Star Trek: Voyager episode where the crew discards a new propulsion method, the quantum slipstream drive, because the field becomes unstable after a little while. Nobody brings up the possibility of using QSD for repeated hops until they get home. (Granted, the Anthropic Principle requires them to not consider this or else the show would be over.)

Video Games
• This fallacy is frequently the driving force behind Too Awesome to Use items or power-ups in video games; instead of using that all-powerful item in a situation that a player knows it would be helpful, they elect not to use it on the off-chance that an even more optimal situation will present itself somewhere down the line. As a result, such items quite often end up sitting in the player's inventory for a long period of time before they get used, if they get used at all.
• This is often used by people who complain about the Tribunal in League of Legends. "The Tribunal is supposed to punish trolls. There are still trolls in the game, therefore it doesn't work."
• In the Laurentia story arc from Nexus Clash, this was the Fatal Flaw of Lucien Moreau. A spectacularly lucky man who enjoyed great success at everything he put his mind to, Lucien imagined that his only suitable successor would be one who not only matched his achievements, but lacked the flaws and shortcomings that had held him back from doing even more. When all four of his children turned out to be merely excellent and not perfect, his backlash and meddling in their lives created enough problems that when he died, it kicked off a Succession Crisis that ended in a way that honored none of his will.
• This is the main reason why Mercy in Overwatch was completely re-worked. Under her old ability kit, the developers noticed that players would play Mercy too passively and were more than willing to pocket her active ultimate (which resurrected any dead teammates in her vicinity). Instead of "wasting" it on one or two revivals, players would try to wait for a moment for a near-or-full-team revive, and usually wind up not using it and being unhelpful if a perfect scenario did not present itself. Thus, the developers reworked her character where she has a revival ability on a 30-second cooldown and an ultimate that enhanced her abilities, allowing players to be more aggressive in keeping players alive instead of being trapped in the fallacy.

Webcomics
• Discussed this strip of The Order of the Stick, when Roy is getting evaluated by a daeva. The daeva says humans should just accept that they are not infallible and just try to be the best they can.
Daeva:...But it's the struggle that matters. It's easy for a being of pure Law and Good to live up to these ideals, but you're a mortal. What matters is when you blow it, you get back up on the horse and try again.

Other
• There’s that old saying: if a thing is not worth being well done, then it’s not worth being done at all. Which itself is an inversion of an older saying that defies this trope — "If a thing's worth doing, it's worth doing right."
• The ultimate example is rejecting anything you feel like on the basis that it has been imperfectly proven; for example, rejecting the existence of China on the basis that you have never seen it.note  This inevitably results in a philosophical concept called solipsism since it is impossible to prove beyond all possible doubt anything barring your own mind (maybe not even that).
• People who attempt to scare people into abstaining from sex often use this fallacy, with the argument that since condoms don't prevent pregnancy and STDs 100% of the time, they are useless. The "perfect" solution of "abstinence" is also Begging the Question, since most people who want a method of preventing pregnancy and STD transmission want it because they intend to have sex. It's rather like saying the best way to avoid straining muscles during a workout is to not exercise.
• Used often by anti-vaccinationists. Their reasoning: a particular measles vaccine only protects 95% of the time, so they'd rather take their chances with a potentially fatal disease. In addition to being an instance of this fallacy, this reasoning also ignores that, due to herd immunity, 95% of the time is more than enough.
• Likewise, in many cases the anti-vaccine group uses the potential for side effects to argue against vaccines in their entirety, often failing to do a cost-benefit analysis for the vaccines. For example, the smallpox vaccine carries a very real risk, as it is composed of a live virus (the cowpox virus). If one chooses to vaccinate a country with the smallpox vaccine, some people will get sick with cowpox. However, when the world began vaccinating against smallpox, an estimated two million deaths per year were due to smallpox, with many of the remaining cases becoming disfigured. This link summarizes the costs of vaccination (warning: graphic images of disease state). The world chose eradication, knowing some people would be adversely affected by the vaccine, over the millions more who would die terribly from smallpox. Furthermore, because of the vaccine, smallpox was eradicated in 1979; the vaccine would be irrelevant today if it weren't that some nations may attempt to weaponize the virus.
• Penn and Teller explain this fallacy and its relevance to vaccines for laypersons here. NSFW due to strong language, as expected from Penn and Teller.
• Opportunistic vendors of quack medicine use this fallacy all the time in the US. US law requires full disclosure of any and all side effects or known problems with any conventional, approved medical intervention. However, if a product makes no specific claims about treating a condition, symptom, or disease, then it is not bound to do so. As long as a product sticks to empty statements like, "Boosts your immune system!" and not specific, testable claims like, "Causes 95% of test subjects to develop Memory B cells capable of a rapid response on second exposure to Pathogen X!", the sellers of these products escape government oversight, regulation, and liability. These folks can point out the shortcomings of science-based medicine, but are under no obligation to provide scientific testing for their product and cannot be taken to task for failing to do so. Naturally, using this fallacy is in the marketing toolbox for these products.
• Common in environmentalism regarding fossil fuel industries and incineration: creation of new facilities is opposed because despite being cleaner, safer and more efficient, they do not perfectly solve the problem of pollution. The fact that the net result is antiquated, dangerous and more heavily polluting facilities being retained long past their service life is ignored.
• The responses to a single case of HIV being reported in the American porn industry: dozens of activists screaming that the industry's voluntary testing system was worthless, because it had not prevented someone from contracting HIV in the first place. They ignored the fact that this system was what gave the porn industry an infection rate vastly, vastly lower than that of the general population. Though as in the above example, it also resulted in some members of the porn industry being shocked that the system was not 100% perfect.
• Among people opposed to welfare, it's used thus: "In spite of welfare, there are still poor people, therefore welfare doesn't work."
• Similarly, like any other system, there will be people trying to abuse it. Arguing that welfare is bad because of welfare fraud ignores the balance between making the system fraud-proof and making it accessible enough to people who genuinely need it.
• This is often used by those who oppose animal testing. They cite the fact that animal testing isn't 100% perfect as a reason to do away with it altogether, even though we're still much better off with it than we'd be without it. (For the concerned, the law requires that researchers use non-animal analogs whenever they're available. Animal testing is only used when there is no other option.)
• This comes up all the time in politics, usually in the form of refusing to support certain candidates or laws because they don't completely solve our problems. It's a major cause of We ARE Struggling Together, as factions push for their perfect solutions.
• And a Diet Coke is one Played for Laughs; while it won't make you lose a noticeable amount of weight, drinking diet soda does cut some empty calories and if you don't eat fast food too often, getting a diet drink, unsweetened tea, black coffee or water the times you do isn't actually a bad idea. That's not even getting into the fact that nobody really thinks a Diet Coke will help them lose weight if they don't eat other healthy food.
• Used against the theory of evolution. Some claim that evolution cannot be correct, because it doesn't explain how life began. While technically right, no-one has claimed it does; finding out how life began is an entirely different scientific branch. It is also used with the fossil record, where when transitional fossils are demonstrated to exist, the creationist will demand the transitions between those transitions until a fossil is not found, which is then used as grounds to dismiss the entire fossil record. Sometimes followed by God of the Gaps argument, depending on what kind of person you're dealing with.
• The internalization of this fallacy is common in people suffering from anxiety and depression: "whatever I do won't be perfect, therefore it's not worth doing at all". Therapy for both conditions often involves getting over the need to be perfect.
• The fringe argument that biological sex is a social construct (not just gender) is based around arguing that since the biological description of a sexually dimophic species doesn't apply to the entire human population, it doesn't matter that it describes a good 99% of it.

http://tvtropes.org/pmwiki/pmwiki.php/Main/PerfectSolutionFallacy