 Every formal language \(\mathbf{L}\) gives rise to a set of possible worlds in a canonical way. A model of \(\mathbf{L}\) assigns a truth value to every sentence in \(\mathbf{L}\) by first, assigning a truth value to ever atomic sentence and then, assigning truth values to all other sentences by respecting the intended meaning of the connectives. We write \( Mod_{\mathbf{L}} \) for the set of all models of \(\mathbf{L}\). Thus, each language \(\mathbf{L}\) induces a finitary field \(\mathbf{A}\) over the set of all models for \(\mathbf{L}\). \(\mathbf{A}\) is the set of propositions over \(Mod_{\mathbf{L}}\) that are expressed by the sentences in \(\mathbf{L}\). \(\mathbf{A}\) in turn induces a unique smallest \(\sigma\)-field \(\sigma(\mathbf{A})\) that contains \(\mathbf{A}\).