Assorted laws and paradoxes I can never remember

Eponymous, mostly

I always need these laws but they are not very mnemonic, y’know? The list of Hacker’s Laws is another nice one here.

Jevons Paradox

In economics, the Jevons Paradox (/ˈdʒɛvənz/; sometimes Jevons effect) occurs when technological progress or government policy increases the efficiency with which a resource is used (reducing the amount necessary for any one use), but the rate of consumption of that resource rises due to increasing demand. The Jevons paradox is perhaps the most widely known paradox in environmental economics.

See also induced demand.

Goodhart’s law

Goodhart’s law is an adage named after economist Charles Goodhart, which has been phrased by Marilyn Strathern as “When a measure becomes a target, it ceases to be a good measure.”

Goodhart first advanced the idea in a 1975 article, which later became used popularly to criticize the United Kingdom government of Margaret Thatcher for trying to conduct monetary policy on the basis of targets for broad and narrow money. His original formulation was:

Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes.

The verb form is fun as in don’t goodhardt yourself.

I occasionally embarrassingly confuse Goodhart’s law with the next one:

Godwin’s Law

Godwin’s Law

is an Internet adage asserting that “As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1”.

Gresham’s Law

Gresham’s law

The law was however named after Sir Thomas Gresham, a sixteenth-century financial agent of the English Crown in the city of Antwerp, to explain to Queen Elizabeth I what was happening to the English shilling. Her father, Henry VIII, had replaced 40 percent of the silver in the coin with base metals, to increase the government’s income without raising taxes. Astute English merchants and even ordinary subjects would save the good shillings from pure silver and circulate the bad ones; hence, the bad money would be used whenever possible, and the good coinage would be saved and disappear from circulation.

This one is fertile for metaphor despite sounding boring. Consider it applied by critics to Bitcoin, where we might argue that illicit uses of Bitcoin will drive out licit uses. Or by Bitcoin fans to argue that Bitcoin will drive out “fiat” currency.

Moore’s Law

is the observation that the number of transistors in a dense integrated circuit doubles about every two years. The observation is named after Gordon Moore, the co-founder of Fairchild Semiconductor and CEO of Intel…

The doubling period is often misquoted as 18 months because of a prediction by Moore’s colleague, Intel executive David House. In 1975, House noted that Moore’s revised law of doubling transistor count every 2 years in turn implied that computer chip performance would roughly double every 18 months

Moore’s Law of Mad Science

Moore’s Law of Mad Science

Every eighteen months, the minimum IQ necessary to destroy the world drops by one point.

Poe’s Law

How do you tell if the Landover Baptist Church is real or satire? This kind of thing is a “Conservapedia problem”. Apparently the mechanism is called “Poe’s Law”.

The core idea of Poe’s Law is that a parody of something extreme can be mistaken for the real thing, and if a real thing sounds extreme enough, it can be mistaken for a parody (all because parodies are intrinsically extreme, in case you haven’t noticed it). This can also happen to someone whose picture of the opposing position is such a grotesque caricature that it renders them unable to tell parody from reality.

See also TVTropes.

Zawinski’s Law of Software Envelopment

Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.

attributed and refuted.

These days it is more likely to grow until it includes a web browser.

Hofstadter’s Law

It always takes longer than you expect, even when you take into account Hofstadter’s law.

Littlewood’s law of miracles

HT Gwern in Littlewood’s Law of Media

[This] illustrates a version of Littlewood’s Law of Miracles: in a world with ~8 billion people, one which is increasingly networked and mobile and wealthy at that, a one-in-billion event will happen 8 times a month.

Human extremes are not only weirder than we suppose, they are weirder than we can suppose.