Clarify by its practical effects

In "How to Make Our Ideas Clear", Peirce offers a rule for dissolving foggy disputes about what something would "really" be: to clarify a conception, ask what conceivable, observable practical difference it would make for it to be true rather than false. The whole content of an idea lies in the effects we can expect from it. This is the pragmatic maxim. A difference that makes no difference in experience is an empty difference: the dispute has become merely verbal.