 One natural criterion is the following. We could say that a response to a question counts as a proper answer just in case it resolves the issue that the question raises. If we adopt this criterion then we also have to impose a certain structural condition on question-meanings. That is, question-meanings cannot just be defined as arbitrary sets of propositions, as in the theories of Hamblin (1973) and Karttunen (1977). Rather, they should be defined as downward closed sets of propositions. That is, if a question meaning contains a certain proposition \(\alpha\), then it must also contain all stronger propositions \(\beta \subseteq \alpha\). After all, suppose that \(\alpha\) is an element of the meaning of a question \(Q\). Given our answerhood criterion, this means that \(\alpha\) corresponds to an issue-resolving response to \(Q\). But then every \(\beta \subseteq \alpha\) corresponds to an even more informative, and therefore also issue-resolving response. So, given our answerhood criterion, \(\beta\) must also be an element of the meaning of \(Q\).