Perfect Solution Fallacy

Also Called:
 * Binary thinking
 * Nirvana Fallacy (No, this has nothing to do with Kurt Cobain.)

A subcategory of False Dichotomy, the Perfect Solution Fallacy is arguing that a course of action is no good because it isn't 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 without worth. 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, using them won't solve the problem completely. 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 views ideally, regardless of whether his opponent would view the result as perfect or even desirable.

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.

There is a flip side to this fallacy. Some people will believe that their solution is perfect, and will defend it at all costs.

This fallacy is the basis of the proverbial admonition, "Don't let the perfect be the enemy of the good."

Looks like this fallacy but is not:
 * Rejecting a solution which actually does prevent one agreed to be better from being implemented.
 * 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.
 * Rejecting a solution because it has an unacceptable cost-to-benefit ratio.
 * Rejecting a solution because of differing projected cost-benefit ratios, at least until the projections are agreed upon.
 * Rejecting a solution because of different values to the costs and benefits, where one side values a particular cost or benefit more or less than the other.
 * Pointing out that a choice didn't work as well as anticipated, after it's been implemented.
 * Asking if there is a solution with a better one. There is nothing wrong with wanting a perfect solution; but there is with rejecting a solution because it does not have guaranteed success.
 * Rejecting an argument or claim that something is perfect, due to a proven imperfection.

Comic Books

 * In Irredeemable the Fatal Flaw behind the Plutonian's Face Heel Turn was the criticism he received from the population after all his acts of heroism, it is implied that he has a pathological desire to have everyone love him, and simply couldn't tolerate any criticism whatsoever, no matter how justified.

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?
 * A recent 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.)
 * Which means the Daily Show's argument is an example of False Dichotomy as the usual counter position is cutting spending not raising taxes on the other half.
 * And another usual counter position is to invoke the Laffer Curve and suggest that lowering marginal tax rates will eventually increase overall tax revenue.
 * Also, the original point that $700 billion will not pay off a debt that's already in the trillions is simple math.

Tropes

 * And a Diet Coke is a specific example of this fallacy, arguing that even the smallest attempt to cut back on sugar is futile. Sugar sodas actually contribute quite a bit to obesity and getting rid of them can yield significant results to one's health.
 * Surely that trope is not saying that the attempt is futile, just that it is incongruous with consuming an excessively large meal at the same time?

Video Games

 * This is often used by people who complain about the Tribunal in League of Legends. "The Tribunal is supposed to eradicate trolls. There are still trolls in the game, therefore it doesn't work."
 * This is a rare case where this fallacy actually makes sense. If something is eradicated, then there are none left, so if X is meant to eradicate Y, and there is still Y, X has not eradicated Y.
 * The funny thing is, the Tribunal in League of Legends wasn't even meant to "eradicate" trolls in the first place - it was meant to more easily punish trolls and discourage people from being trolls. Similar to Valve forbidding people from speaking in Dota 2 if they're being a complete douchebag. However; Riot and Valve's systems does not do anything to discourage "Stop Having Fun!" Guys from ruining the community of their games.

Web Comics

 * Discussed this strip of Order of the Stick, when Roy is getting evaluated by an angel. The angel says humans should just accept that they are not infallible and just try to be the best they can.

Real Life

 * The ultimate example is rejecting anything you 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. This inevitably results in a philosophical concept called solipsism since it is impossible to prove beyond all possible doubt anything barring your own mind.
 * 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."
 * 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.
 * 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; never mind that they do so over 98% of the time. The "perfect" solution of "abstinence" is also Begging the Question, since what is actually being advocated is abstinence-only education which the argument assumes will result in 0% of people having casual sex. In fact, 60% of people who have such education will go on to have casual sex anyway, and will be 30% less likely to use any form of contraception; the "perfect" solution is statistically massively inferior to the imperfect one.
 * 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.
 * 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 the 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."
 * This fallacy is argued the other way too. Because a purely private economy cannot be counted on to reliably support all members of society, our economy should be 100% government run. Of course, supporters and detractors of welfare usually argue from positions other than these two straw extremes.
 * 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.)
 * The "God of the gaps" argument of theology, as used by creationists to discredit evolution: those things that science is not able to explain must have come from God. Of course, when science does present explanations for things previously unexplained, God is still in the remaining gaps; this is Moving the Goalposts, of course.
 * Of course, this is a straw position as the "God of gaps" term was coined by atheists as a rebuttal to a generalization of a set of arguments made by some creationists. The arguments themselves tend to be more specific and usually based on perceived contradictions (i.e. not just "you don't know this so your theory sucks" but "your theory says this thing which contradicts that other thing that either your theory says or is observed in nature, therefore your theory sucks").
 * The term "God of the gaps" was coined by atheists to describe the use of this fallacy by theists. That it is sometimes misapplied does not mean that theists never commit this fallacy.
 * And it appears both sides above ignore the third option that God could have created the scientific laws that govern the universe.
 * And then from the other side, the problem of evil. Why would a good God allow things bad things to happen to good people? Slightly subverted in that many Christian theists do in fact claim God to be perfect (or at least all-knowing, all-powerful, and all-good), so any apparent imperfection must be justified (and indeed, there are many strong arguments that attempt to just that).
 * The U.S. EPA rejecting skimmers from The Netherlands from cleaning 99% of the oil from the water they pick up then return to the sea because the EPA requirement says that water can only be returned to the Gulf of Mexico if it's 99.9985% pure. The EPA finally allowed use of the equipment, but not the Dutch ships or crews.
 * This actually is sickenly common when it comes to stuff like new technologies. Not everyone supports new technology or even considers it anything but a gimmick because it's not instantly performing as well or outperforming current technologies. In reality, these things TAKE TIME - the current technologies were like that at one point. One can only imagine where we'd be if people reacted to such things as the automobile.
 * 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.
 * 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. When told You Could Always Edit It Yourself, they claim disdain for cleaning up other people's messes.
 * Quite a few creators object to digital distribution schemes because they don't make as much money as they do selling physical copies. They alternative is usually piracy, which they obviously aren't making any money at all on.
 * They're also ignoring that delivery costs are enormously less and production costs for every copy after the first are zero.