This is a great rule

The original Reasonable Person Principle from CMU is a great way to think about communities of people, especially for online communities when you do not see someone in person: http://www.cs.cmu.edu/~csd-grad/reasonableperson.html

in reference to:

"In spite of all our best efforts, disconnects and misunderstandings
will still occur. The Reasonable Person Principle is an approach
for working through them. When a disconnect occurs, it often seems
that the other person is behaving unreasonably (“I can't believe X
could have done Y!”). The Reasonable Person Principle says that
you should always assume that other people are behaving reasonably,
even if it doesn't appear that way. Rather than attacking them,
ask questions to find out why they did what they did. Almost always,
you'll discover that there is a reasonable explanation. This way,
you can defuse the situation quickly and move forward constructively."
- Startup Company Culture (view on Google Sidewiki)