All three of the controversial logical truths of SQML—BF, CBF, and \(\Box\textbf{N}\)—are invalid in KQML, that is, in KQML, they are not logically true. The key in each case is KQML’s modification of the way that quantified formulas are evaluated at worlds. As we saw in §3.3 above, the validity of BF in SQML—its truth in every interpretation—depends essentially on the fact that, in evaluating an existentially quantified formula \(\exists\nu\varphi\) at an arbitrary possible world \(w,\) the i