For nothing ought to be posited without a reason given, unless it is self-evident (literally, known through itself) or known by experience or proved by the authority of Sacred Scripture.

Pluralitas non est ponenda sine necessitate. A plurality (of reasons) should not be posited without necessity.

Of two equivalent theories or explanations, all other things being equal, the simpler one is to be preferred.

Whenever two hypotheses cover the facts, use the simpler of the two.

Entities are not to be multiplied beyond necessity.

No more things should be presumed to exist than are absolutely necessary.

Plurality should not be assumed without necessity.