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

Entities should not be posited unnecessarily.

God's existence cannot be deduced by reason alone.

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

Plurality should not be assumed without necessity.

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

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