Occam's razor (or Ockham's razor), is the meta-theoretical principle that "entities must not be multiplied beyond necessity" (entia non sunt multiplicanda praeter necessitatem). The term razor refers to the act of shaving away unnecessary assumptions to get to the simplest explanation.

 

The principle is attributed to 14th-century English logician, theologian and Franciscan friar, William of Ockham. Occam's razor may be alternatively phrased as pluralitas non est ponenda sine necessitate...

Interview of Milton Friedman by Phil Donahue, 1979

"Why would “smarter” brains work less hard? One strong bet is that when we are inexperienced—when we still have a lot to learn—we have to make a conscious effort to think about what we’re doing. But later, after we’ve become more adept, much of what initially took effort becomes automatic.