Situation Semantics

Origin. Barwise, Perry (1983). Situations vs possible worlds. Partial information. Constraints and infons. Foundation of situated cognition.

Models. Situations: partial states of affairs. Infons: situation types. Constraints: lawful relations. Partiality central. Ecological information.

Formalism.

Situations: s: actual partial state of affairs. Not total (unlike possible worlds). Part of reality. Located, concrete.

Infons: ⟨⟨R, a₁,...,aₙ; 1⟩⟩: R holds of a₁,...,aₙ. ⟨⟨R, a₁,...,aₙ; 0⟩⟩: R doesn't hold. Basic information units. Polarity included.

Support: s ⊨ σ: situation s supports infon σ. s makes σ true. May be partial: neither supports nor denies. Partiality key.

Situation types: Type S: situations satisfying conditions. s : S means s is of type S. Abstract situations. Classification.

Constraints: S₁ ⇒ S₂: situations of type S₁ are of type S₂. Lawful connections. Carry information. Ecological.

Information carried: If s : S₁ and S₁ ⇒ S₂, then s carries info that S₂. Smoke carries info of fire. Constraint-based meaning. Ecological semantics.

Propositions: Structured: situation + type. Prop = situation that is of type S. Austinian propositions. Situated truth.

Symbols.

Symbol	Unicode	Meaning
s	—	situation
⊨	U+22A8	supports
⟨⟨R,a;i⟩⟩	—	infon
⇒	U+21D2	constraint

Metatheory. Partial situations. Infons. Constraints. Ecological information.

Applies to. Semantics. Information theory. Context. Situated cognition.

Limitations. Complexity. Formalization variations. Less compositional. Limited uptake now.