Occam's razor basically states the simplest solution is usually the correct one. It is a personal favorite of mine, because I see it so often.
For example: "No one understands what I am saying, it must be because they went to a different school district, where they didn't teach it and they don't have the background to understand it"
No, Occam's Razor would say that they just don't want to listen to you.
To bring this rocketing into my reality, I just get this phone call:
Him: Is Domain XYZ down? I can't ping it!
Me: Well XYZ is not listed in DNS, so you wouldn't be able to ping it, the key indicator of it being down is that no one in the building would be able to get on it.
Him: Can you get on it?
Me: Yes, I have been on all day.
Him: But I can't see it!
Occam's Razor here would state that the problem may be on your side rather than the domain that serves the entire building is down, but this means you would have to do work to fix it, instead of shoving it off on me. This is part of my own frustration. Yes, I did design the domain, and yes I do know it quite well, but there is a team of eight people that have the responsibility to support the day to day operations, and I am not on it. I'm busy on Fubar damnit!