John Sowa writes:
Theories of semantics based on possible worlds cannot derive purpose or intention from collections of worlds, no matter how big, or from collections of situations, no matter how small. In their theory of situations, Barwise and Perry (1983) tried to use finite situations rather than infinite worlds as a basis for deriving the semantics of propositional attitude verbs, such as hope, wish, want, or fear. But the situations they used as examples were not arbitrary, random chunks of the world. For every sample situation in their book, there was an unstated reason why some agent focussed attention on that situation rather than any other. The reason why an agent selects a situation as a topic of interest is a more fundamental clue to its meaning than the situation itself. (emphasis added)
An interesting thought.
It is unfortunate, however, that Sowa uses (Barwise and Perry 1983) as the principle reference text for situation theory, given that the theory underwent so many changes in the following decade. For example, Sowa writes that Barwise and Perry identify situations with chunks of space-time; but if that were indeed their characterization at the time, it was certainly not their conception later.
For example, (Barwise 1989, 259) writes:
When situation theory is applied to Japanese, say, then when
we talk about the world, or reality, we do not mean just physical reality. We mean all that is part of the real world of the Japanese speaking community. This includes things like thoughts, sentences, customs, manners, elections, wars, and the like, abstract objects as well as concrete objects, spatio-temporally located objects but also abstract objects like natural numbers and sets. ...When we talk about a part, or portion of the world, in the former case, we mean some part of this all encompassing reality. We do not mean to restrict to parts that are determined by spatio-temporal location. Nor do we mean to restrict to portions determined by some objects, properties and relations. We want to include things like the part of the world I am seeing right now, and the part of the world I am thinking about. Thus we must be careful not to bring intuitions to bear on the part-of relation that are really intuitions about time and space, or are intuitions about sets of objects.
Barwise makes clear that he neither conflates situations with chunks of space-time nor considers situations to be entirely independent of the agents who individuate them.
Nonetheless, the agent-relativity of situations and situation theory's realist bent sit together rather uncomfortably. Scarcely will you find in the literature any serious discussion of the semantics of sentences whose semantic contents are descriptions with non-actual constituents, which if we are to be just constitute a substantial portion of our daily discourse (and not only in the most obvious places, either). The closest I know of, is in Edward Zalta's (1991) discussion of ordinary objects with external properties and encoded objects which exemplify internally defined properties.
Barwise, Jon. 1989. The Situation in Logic. CSLI Lecture Notes 17. Stanford, CA: Center for the Study of Language (CSLI). http://standish.stanford.edu/bin/detail?fileID=1848697363.
Barwise, Jon and John Perry. 1983.
1983. Situations and attitudes. MIT Press.
Zalta, Edward N. 1991. A theory of situations. In Situation Theory and Its Applications, ed. Jon Barwise, Jean Mark Gawron, Gordon Plotkin, and Syun Tutiya, 2:81-111. CSLI Lecture Notes 26. Stanford, California: Center for the Study of Language (CSLI).