“With all things being equal, the simplest explanation tends to be the right one.”
“All things being equal, the simplest solution tends to be the best one.”
“Entities should not be multiplied beyond necessity.”
“Entia non sunt multiplicanda praeter necessitatem.”
“Pluralitas non est ponenda sine neccesitate. (Entities should not be multiplied unnecessarily.)”
“When you have two competing theories that make exactly the same predictions, the simpler one is the better.”