Murphy's Law: Anything that can go wrong, will go wrong.
Lindy's Law (Lindy Effect): The future life expectancy of a non-perishable thing (like an idea or technology) is proportional to its current age.
Laws of Infernal Dynamics: (1) An object in motion will always be headed in the wrong direction. (2) An object at rest will always be in the wrong place. (3) The energy required to change either state will always be more than you wish to expend, but never so much as to make the task impossible.
Yhprum's Law: Anything that can work, will work.
Sod's Law: The worst possible outcome tends to happen at the worst possible moment.
Finagle's Law: Anything that can go wrong, will — at the worst possible time.
Gilbert's Law: The biggest problem with a job is that nobody tells you what it is.
Hanlon's Razor: Never attribute to malice that which can be adequately explained by incompetence.
Parkinson's Law of Triviality (Bikeshedding): People spend more time discussing trivial matters than important ones.
Time & Productivity
Parkinson's Law: Work expands to fill the time available for its completion.
Hofstadter's Law: Everything takes longer than you expect, even when you take Hofstadter's Law into account.
Student Syndrome: People start working seriously only when the deadline becomes urgent.
Carlson's Law: Interrupted work takes longer than uninterrupted work.
Illich's Law: After a certain number of hours, productivity falls sharply.
Meskimen's Law: There's never enough time to do it right, but always enough time to do it over.
Engineering & Software
Brooks's Law: Adding manpower to a late software project makes it later. (Corollary: Nine women cannot make a baby in one month.)
Conway's Law: Systems mirror the communication structure of the organizations that build them.
Gall's Law: A complex system that works evolved from a simple system that worked.
Zawinski's Law: Every program attempts to expand until it can read email.
Knuth's Optimization Principle: Premature optimization is the root of much evil.
Kernighan's Law: Debugging is twice as hard as writing the code in the first place.
Decision Making & Thinking
Occam's Razor: The simplest explanation is usually the best.
Hitchens's Razor: What can be asserted without evidence can be dismissed without evidence.
Chesterton's Fence: Don't remove something until you understand why it was put there.
Goodhart's Law: When a measure becomes a target, it ceases to be a good measure.
Cobra Effect: Incentives often produce the opposite of the intended result.
Dunning-Kruger Effect: People with low competence tend to overestimate their competence.
Law of Unintended Consequences: Actions often have consequences that were not anticipated.
Business & Management
Peter Principle: People are promoted until they reach their level of incompetence.
Dilbert Principle: The least competent people are often promoted into management.
Shirky Principle: Institutions preserve the problem they were created to solve.
Price's Law: A small fraction of people often produce a large fraction of results.
Pareto Principle (80/20 Rule): Roughly 80% of effects come from 20% of causes.
Parkinson's Second Law: Expenditure rises to meet income.
Meetings & Organizations
Parkinson's Law of Meetings: Time spent discussing an item is inversely proportional to its importance.
Law of Bureaucratic Displacement: The process becomes more important than the result.
Committee Principle: A camel is a horse designed by a committee.
Iron Law of Oligarchy: Every organization eventually becomes dominated by a small group.
Markets & Investing
Keynes's Market Observation: The market can stay irrational longer than you can stay solvent.
Maximum Pain Theory: Markets often move where the largest number of traders lose money.
Recency Bias: People expect recent trends to continue indefinitely.
Taxi Driver Indicator: When everyone is giving stock tips, caution is warranted.
Greater Fool Theory: One can profit from overvalued assets if a greater fool will buy later.
Law of Mean Reversion: Extreme market moves tend to move back toward average levels over time.
Human Nature
Gumperson's Law: The probability that something will happen is inversely proportional to its desirability.
Sturgeon's Law: Ninety percent of everything is crap.
Sayre's Law: In any dispute, the intensity of feeling is inversely proportional to the value of the issues at stake.
Observation Selection Effect: You notice things only after becoming aware of them.
Law of Familiarity: The more often people see something, the more they tend to like it.
Internet & Technology
Cunningham's Law: The best way to get the right answer online is to post the wrong answer.
Metcalfe's Law: The value of a network grows roughly with the square of the number of users.
Moore's Law: Computing power tends to double roughly every two years.
Wirth's Law: Software becomes slower faster than hardware becomes faster.
Etorre's Observation: The other line always moves faster.
Betteridge's Law of Headlines: Any headline ending with a question mark can usually be answered with "No."
Project Management
Ninety-Ninety Rule: The first 90% of a project takes 90% of the estimated time; the remaining 10% takes also 90% of the estimated time.
Law of Project Schedules: The later a project is, the more effort is spent explaining why it is late.
Iron Triangle: You can optimize only two of: fast, cheap, good.
Data, Models & AI
All Models Are Wrong: All models are wrong, but some are useful.
Garbage In, Garbage Out (GIGO): Bad inputs produce bad outputs.
Streetlight Effect: People search where it is easiest to look rather than where the answer is likely to be.
McNamara Fallacy: Making decisions based only on measurable data while ignoring important unmeasurable factors.
Law of Instrument: If all you have is a hammer, everything looks like a nail.
Bonus One-Liners
No plan survives first contact with reality.
Every shortcut creates a future detour.
Temporary solutions become permanent.
The easiest way to solve a problem is to avoid creating it.
If you automate a bad process, you get bad results faster.
Success has many parents; failure is an orphan.
The more urgent a meeting, the less likely it needed to happen.
The person who wrote the code is no longer available.