Not so stable
According to Michael Dummett, we may think of the meaning of an expression as given by the principles governing the use we make of it. The principles regulating our linguistic practices can then be grouped into two broad categories (Dummett 1973: 396, 1991: 211). We might state them as follows: 
 
I-principles: state the circumstances under which an assertion of a sentence containing the expression in question is warranted. 
 
E-principles: state the consequences of asserting a sentence containing the expression. 
 
In the case of the logical constants, we may associate a constant's I-principles with the set of its introduction rules and its E-principles with the set of its elimination rules (Dummett 1973: 454).1