"Ockham's Razor" is a theoretical principle, attributed to the medieval philosopher, William of Ockham, who particularly opposed the unjustified creation of new terms in philosophy. It states that:
any explanation of any phenomenon should make as few assumptions as possible, ruthlessly eliminating those that make no difference either in terms of observable predictions or for the explanatory hypothesis or theory
Ockham did not, of course, invent the principle, but made frequent use of it, most often in this form: Numquam ponenda est pluralitas sine necessitate which roughly translates as 'Plurality ought never be posited without necessity'.
Recommended readings
Ockham's Razor and Its Improper Use
Walach, H. & Schmidt, S. (2005). Repairing Plato's Life Boat with Ockham's Razor. The Important Function of Research in Anomalies for Mainstream Science. Journal of Consciousness Studies
