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

Entities should not be posited unnecessarily.

Plurality is not to be posited without necessity.

What can be explained by the assumption of fewer things is vainly explained by the assumption of more things.

Simpler explanations are, other things being equal, generally better than more complex ones.

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.

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