Our starting points are minimal partial models of quantifier free formulas. This restriction on formulas can be relaxed, though not arbitrarily. The idea is that we start with a specific world description, and instantiate it in a minimal model. The Situation in Logic. Center for Study of Language and Information , Stanford, California, 1989.
Most researchers probably suspect that real reasoning is semantic.
Toward this end, we introduce the concept of default information structures. The Situation in Logic. Center for Study of Language and Information , Stanford, California, 1989. We also remark here that the idea to use partial information in studying nonmonotonicity is not new. The Situation in Logic.