 Recall from  Section 1.2  that a deductive consequence relation satisfies Soundness, i.e. that \(\alpha\vdash \beta\) only if \(\beta\) is true in all the worlds in which \(\alpha\) is true. As we have discussed, non-monotonic logics are ampliative, and therefore must violate Soundness. Shoham (1987) inaugurated a semantics for non-monotonic logics in which \(\alpha\dproves \beta\) only if \(\beta\) is true in a “preferred” set of worlds in which \(\alpha\) is true. On a typical interpretation, these are the most typical, or most normal worlds in which \(\alpha\) is true.