An important feature of human common sense is that human knowledge of a phenomenon is often readily elaborated to take new information into account. It is important that logical theories of common sense phenomena also have this property. [McC99] has a detailed discussion.
Situation calculus theories benefit from several kinds of elaboration. Section 4 discusses elaborating the stuffy room theory by adding occurrence axioms for a person being motivated to open a vent when the room becomes stuffy. [McC92] constructs a theory of a persons travel planning which can be elaborated by adding a sentence asserting that he loses his airplane ticket at a certain point in his journey. Because the reasoning depends on minimizing occurrences, we can no longer conclude that the original travel plan will succeed.
In general, elaboration tolerance concerns making it easy to modify a theory, but the simplest kind of elaboration is to add one or more sentences to an existing theory. It is desirable that elaborations be doable in this way as much as possible. [McC99] discusses when this can and cannot be done for a given theory and how to make theories for which elaboration by conjoining sentences is possible. Theories expressed in natural language have this kind of elaboration tolerance to a high extent.