Razors

A philosophical razor is a logical device that's effective at shaving away implausible explanations.  This is sometimes generalized to include any useful philosophical adage.   I intend to keep updating this list as I discover new ones.

Occam's razor:  The simplest explanation is the most likely one.  It doesn't necessarily mean the simplest explanation is right, but we can save a lot of time not worrying about unnecessarily complex stuff.

Hanlon's razor:  "never attribute to malice that which can be attributed to stupidity."  Sometimes this is expressed as "Do not invoke conspiracy as explanation when ignorance and incompetence will suffice, as conspiracy implies intelligence"

Popper's falsifiability principle:  It's not scientific unless it can be subjected to an experiment which might prove it false.  (this is actually due to Newton)

The golden rule: Don't do unto others that which you would not have them do unto you.

Rawls' veil of ignorance: When deciding the morality of something, imagine that society was completely refashioned, and you do not know who you will be.

Murphy's Law:  If it can go wrong, it will go wrong.  Sometimes this is expressed as: if there's a right way to do something and a wrong way, the wrong way will happen.

It is difficult to get a man to understand something when his salary depends upon him not understanding it.  -Sinclair Lewis

The Peter Principle: In a hierarchy, every employee tends to rise to his level of incompetence.

Sturgeon's Law: 90% of everything is crap. (I think Sturgeon was being very generous....99.9% at least...)

Gresham's Law (and): Bad money drives out the good.  This is valid for any competitive system: If cheating is allowed, pretty soon everybody has to do it in order to be competitive.

Planck's Principle: Science rarely proceeds by changing the minds of those who already have a position; rather, the conservatives die and younger people familiar with the new idea take over the field.  Sometimes expressed as "Science advances one funeral at a time"

Godwin's Law: If any conversation goes on long enough, someone will bring up the Nazis.  Who ever does that is losing.

Parkinson's Law: Work expands to fill the time and cost available

Parkinson's Law of Triviality:  During any meeting, most of the time is spent discussing trivial but easily understood issues, not what matters

To an uninformed person, an informed person seems insane.

  I've been looking for a source for this without success