Proposition that assumptions should be reduced to their minimum. Thus, if two assumptions seem to be equally valid, the simpler one should be preferred. It is attributed to the English philosopher and monk William of Ockham (c.1285-1349) who expressed it as "Entities are not to be multiplied beyond necessity." Also called principle of ontological economy, principle of parsimony, or principle of simplicity. Also spelled as Occham's razor or Occam's razor.