Nirvana fallacy

Demand complete solutions. Avoid the issues by requiring opponents to solve the crime at hand completely. The Nirvana fallacy is a logical fallacy in which one assumes that a perfect solution to a given problem exists, and rejects more realistic answers in favour of it.

The fallacy is an ad hoc moralistic fallacy and an informal fallacy.

The term "Nirvana approach" was coined by the prominent economist Harold Demsetz, who famously wrote:

Alternate names
The best is the enemy of the good. (Le mieux est l'ennemi du bien.)
 * Perfectionism
 * Perfectionist fallacy
 * Perfect solution fallacy

Form

 * 1) The problem X has a perfect solution A.
 * 2) Therefore, imperfect yet realistic solutions B, C and D are wrong because they are inferior to the idealised A.

Examples

 * The argument that abstinence is a perfect form of contraception ignores that most people might actually want to have sex while using the contraception, and therefore assumes a perfect solution. This argument is usually used to reject condoms because they "only" have a 99% rate of preventing pregnancy.
 * The anti-science argument "science does not know everything about X, therefore it is worthless compared to some pseudoscience which claims it does."
 * The anti-intellectual argument that some scientific research doesn't cure cancer, therefore is a waste of money. Bonus irony points when using this argument on the LHC and particle physics in general, which resulted in the radiation therapies for cancers. Particle physics also was responsible for NMRI machines to diagnose cancers earlier. And ion thrusters, because hell yeah!
 * The more woo-prone parts of the environmentalist movement (e.g., hard green) often fall prey to assuming that reducing pollution is worthless, favouring an idealised state where there is no pollution at all.
 * Proclaiming that any medication that has side effects is worthless, or that any treatment less than 100% effective is a waste of time. Also often used by medical quacks who will argue that treatment to mitigate symptoms is pointless because it is not a cure.
 * Chemophobic arguments based on exposure levels which assume any exposure is unacceptable, regardless of whether there is any meaningful risk to health.
 * Mental illness denial based on the argument that since we don't fully understand the causes of mental illness or how exactly the treatments for it work, mental illness therefore must not be real and the treatments must be ineffective and dangerous. Often this argument will refer to historical examples of psychiatric treatments that did more harm than good (e.g., lobotomy) or unsubstantiated claims such as that SSRIs cause homicidal ideation and are responsible for mass shootings.
 * The notion that because a politician or other public figure is not perfect in some area of social justice, that person should not be praised for the positive things they say or do, and perhaps those things should not even be recognised or acknowledged (which is different from saying that anyone who gets it right in any way should therefore be shielded from criticism if when they get it wrong).
 * Apologists who like to couple this fallacy with a false dilemma to claim that if something is only significant on the scale of our human experiences and lifetimes and not on a cosmic and/or eternal scale (e.g. an approach to morals or the effects of human behavior), then it's completely meaningless.
 * Rejecting efforts to abolish animal exploitation on the grounds that "people will not want to stop eating meat, so it's better to focus on killing animals in the best way possible."
 * Gun Extremists in the USA often reject reasonable law and regulation reform on the grounds that "criminals will just ignore laws" or "criminals will get their hands on guns anyways", ignoring the fact that gun laws do in fact reduce crime and the availability of illegal firearms.
 * Advocates of police abolition often vociferously oppose any proposals for reform or restructuring of police services to solve issues within it (e.g. racial bias) on the stated basis that the existence of any police force will potentially lead to these problems, and therefore the only acceptable solution is total abolition.