Finagle’s law is a principle that suggests that the worst outcomes will happen at the most inopportune times. Many consider Finagle’s law a corollary to Murphy’s law, which states that any negative outcomes will eventually happen. Both of these ideas are based on scientific theory around thermodynamics, and have been used in science fiction as well as technological analysis.
Finagle's law is also known as Finagle's law of of dynamic negatives.
Finagle’s law has also spawned its own corollaries, among them O’Toole’s law, which is often explained as entropy, or the tendency of a closed system toward disorder. These ideas, which can be formed scientifically or in a more colloquial sense as a type of pessimism, are sometimes helpful in testing plans and other technological studies. Those who think about Finagle’s law and associated ideas tend to anticipate problems and build in prevention, leading to stronger technologies.
Another element of Finagle’s law is sometimes called "resistentialism," or the "malicious nature of inanimate objects." This is a fairly obscure idea in IT, but something that many technology users might think about when they encounter problems with a device or piece of software. It can often seem like machines or other technologies are "out to get us," despite all evidence against real artificial intelligence. This idea can be traced back to Finagle’s law and related theories.