As we have the ability to create a wiki, it would seem relevant to produce an authoritative list of project management maxims, adages and laws.


  • I can't quite decide if this the right kind of format for PMSE because it's pretty subjective. But in the sprit of fun I've answered it anyway... – Willl Jun 25 '15 at 10:11
  • This realy is an opinion polling question but a good / fun one. consider to post in on PMSE meta. – Tob Jun 26 '15 at 3:42
  • I have noticed that those voting to close have done so because the question is too broad and cannot be answered in a "few paragraphs." An amazing assertion given that Wikipedia has numerous pages of maxims, adages and laws which are condensed to a few paragraphs of lists. – Venture2099 Jun 26 '15 at 9:41

Amara's Law: We overestimate the benefits of technology in the short run and underestimate its benefits in the long run.

Dilbert Principle: The most ineffective workers are systematically moved to the place where they can do the least damage: management.

Dunning-Kruger: Unskilled workers suffer from illusory superiority.

Finagle's Law: What can go wrong will go wrong...at the worst possible time.

Hofstadter's Law: It will always take longer than expected, even if you take Hofstadter's law into account.

Muphrey's Law: When you criticize someone's writing, the criticism will have a grammar or spelling flaw.

Occam's Razor: With multiple alternative explanations, the simplest one is usually correct.

Pareto's Principle: 80% of the consequences stem from 20% of the causes.

Segal's Law: A man with one watch knows what time it is; a man with two is never sure.

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  • I've never seen Hofstadter's law before. That's a good 'un. – Willl Jun 25 '15 at 12:31
  • Surely it's about time someone mentioned Gnome's Law again? ;) – Marv Mills Jun 25 '15 at 13:30

My two favourites are Parkinson's law and Murphy's law (or the more cynical British version, Sod's law).

Parkinson's law

Work expands to fill available time

This is such an important rule to understand when you're scheduling. The moment you say 'this is going to take a week', it suddenly takes a week because people think, 'well, I've got a week so I'll just add this thing' or 'well, I've got a week so I'll just kick back for a day or two'. It's quite closely related to the idea of gold plating.

Murphy's law

Whatever can go wrong, will go wrong

Basically, when you plan for risk this should always be your starting point. Not necessarily to think that things will go wrong but that even edge cases can happen in real life.

A related adage might be Donald Rumsfelds' famous quote:

There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.

When you ignore the horrible English, it actually makes some sense - there are some unlikely risks you can predict (the known unknowns), and some that you can't (the unknown unknowns).

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  • 1
    Moore's Law definition you have there is Murphy's Law. Moore's law is about the doubling of transistors every two years. – David Espina Jun 25 '15 at 11:16
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    See that, right there, is a meta-example of Murphy's Law :) – Marv Mills Jun 25 '15 at 11:18
  • @MarvMills brilliant! – Willl Jun 25 '15 at 11:36
  • @DavidEspina d'oh! Edited that now! – Willl Jun 25 '15 at 11:37

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