High Quality Content by WIKIPEDIA articles! Logical harmony, a name coined by Sir Michael Dummett, is a supposed constraint on the rules of inference that can be used in a given logical system. The logician Gerhard Gentzen proposed that the meanings of logical connectives could be given by the rules for introducing them into discourse. For example, if one believes that the sky is blue and one also believes that grass is green, then one can introduce the connective and as follows: The sky is blue AND grass is green. Gentzen's idea was that having rules like this is what gives meaning to one's words, or at least to certain words. The idea has also been associated with Wittgenstein's dictum that in many cases we can say, the meaning is the use.