 In this kind of dynamic semantics for natural language, the meaning of a sentence does not correspond to a set of truth-conditions, but rather to an action performed on a context. There are two kinds of actions. Predications like \(\texttt{need-help}(x)\) or \(\texttt{met}(m,x)\) are tests. They merely check if every state/assignment in the current context assigns a value to \(x\) that satisfies the relevant predicate; if (and only if) this is the case, the test passes the unaltered assignment on to the output context. In contrast, the existential quantifier is not a test. It has the potential to alter the context by randomly resetting the value of its associated variable. So, \(\exists x(\psi)\) takes a context, randomly changes the value of \(x\) in each assignment in the context and passes these changed assignments on to the output context if they also satisfy the condition contributed by the test \(\psi\).