Also called Principle of Parsimony.
Principle that one should not multiply entities unnecessarily, or make further assumptions than are needed, and in general that one should pursue the simplest hypothesis.
Adoption of this principle, though seemingly obvious, leads to problems about the role of simplicity in science, especially when we are choosing between hypotheses that are not (or are not known to be) equivalent.
There are often different and clashing criteria for what is the simplest hypothesis, and it is not clear whether a simpler hypothesis is pro tanto more likely to be true; and if not, what justification other than laziness there is for adopting it.
Philosophy of Science (1961); journal containing symposium on simplicity