via Lex Communis, an essay arguing that the medieval scholastic William of Ockham never said "Entities should not be multiplied beyond necessity," tracing the geneaology of the idea.
I am under the impression that under medieval nominalists' principle of parsimony, which shirked multiplying seemingly unnecessary entities such as Aristotelian essences, the only necessary cause was God. A fire lights dry wood? No inherent properties in the fire or the wood are necessary to explain the phenomenon. God did it, and it is only the constancy of his will that makes this fire-lighting a regular coincidence.
I doubt that this interpretation of Ockham would be welcomed by those who invoke his name today.