Occam's Razor

The very well known KISS philosophy (Keep It Simple, Stupid) has a more formal version known as Occam's Razor (attributed to William of Occam, a 14th century logician and Franciscan friar in England) which states (ironically, in a complicated way) that "one should not increase, beyond what is necessary, the number of entities required to explain anything". It is an important philosophy in engineering today (where it essentially tells you to fit a straight line between two points, instead of the infinite number of curves possible).

It is also called the Principle of Parsimony and it says that when you have multiple theories making the same predictions, the one that makes the fewest assumptions (and is hence simpler) is the better one. So when you are faced with a choice between multiple explanations or models to explain the same phenomenon, use the Occam's Razor to shave off (I guess that's why it's called a razor) the unnecessary assumptions.

How far can you go while choosing simpler theories? Here's what the venerable guru Einstein says : "Everything should be made as simple as possible, but not simpler."