Entities must not be multiplied beyond necessity.

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

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

When you have two competing theories that make exactly the same predictions, the simpler one is the better.

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

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

Never increase, beyond what is necessary, the number of entities required to explain anything.