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

Plurality should not be assumed without necessity.

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

Entities are not to be multiplied beyond necessity.

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.

Intuitive cognition of a thing is cognition that enables us to know whether the thing exists or does not exist, in such a way that, if the thing exists, then the intellect immediately judges that it exists and evidently knows that it exists, unless the judgment happens to be impeded through the imperfection of this cognition.

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