The term Occam's razor was coined in the middle of the 19th century by William Hamilton, a Scottish mathematician:
Quote:
We are, therefore, entitled to apply "Occam's razor" to this theory of causality. Discussions, p.580 (link)
Different versions exist:
  • Entia non sunt multiplicanda praeter necessitatem Entities should not be multiplied unnecessarily. (Attributed to Occam, does not occur in any of his known works.)
  • Numquam ponenda est pluralitas sine necessitate Plurality must never be posited without necessity.
  • Frustra fit per plura quod potest fieri per pauciora It is futile to do with more things that which can be done with fewer.
For more information see William M Thorburn (1918) "The Myth of Occam's Razor" in Mind 27, pp.345–353 (link). Also, note that the philosopher in question was named William of Ockham (or Occam). Cf. Leonardo or Da Vinci.

Ceci n'est pas un seing.