Occam's razor
From The Big Bang Theory Wiki
Occam's razor is a logic principle that recommends that one should prefer the simplest explanation out of many available explanations for a phenomenon. For further information see [Occam's razor] on Wikipedia.
Sheldon quotes Occam's razor in "The Cooper-Hofstadter Polarization":
Leonard: Leonard: Sheldon, why is this letter in the trash?
Sheldon: Well, there's always the possibility that a trash can spontaneously formed around the letter, but Occam's Razor would suggest that someone threw it out.
