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

With all things being equal, the simplest explanation tends to be the right one.

Plurality should not be assumed without necessity.

It is vain to do with more what can be done with less.

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

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.

3 is a prime, 5 is a prime, and 7 is a prime. Why bother with non-prime numbers when the primes can do everything?