erotetic in the strict sense, pertaining to questions. Erotetic logic is the logic of questions. Different conceptions of questions yield different kinds of erotetic logic. A Platonistic approach holds that questions exist independently of interrogatives. For P. Tichý, a question is a function on possible worlds, the right answer being the value of the function at the actual world. Erotetic logic is the logic of such functions. In the epistemic-imperative approach (of L. Bqvist, Hintikka, et al.), one begins with a system for epistemic sentences and embeds this in a system for imperative sentences, thus obtaining sentences of the form ‘make it the case that I kno. . .’ and complex compounds of such sentences. Certain ones of these are defined to be interrogatives. Then erotetic logic is the logic of epistemic imperatives and the conditions for satisfaction of these imperatives. In the abstract interrogative approach (of N. Belnap, T. Kubigski, and many others), one chooses certain types of expression to serve as interrogatives, and, for each type, specifies what expressions count as answers of various kinds (direct, partial, . . .). On this approach we may say that interrogatives express questions, or we may identify questions with interrogatives, in which case the only meaning that an interrogative has is that it has the answers that it does. Either way, the emphasis is on interrogatives, and erotetic logic is the logic of systems that provide interrogatives and specify answers to them.
In the broad sense, ‘erotetic’ designates what pertains to utterance-and-response. In this sense erotetic logic is the logic of the relations between (1) sentences of many kinds and (2) the expressions that count as appropriate replies to them. This includes not only the relations between question and answer but also, e.g., between assertion and agreement or denial, command and report of compliance or refusal, and (for many types of sentence S) between S and various corrective replies to S (e.g., denial of the presupposition of S). Erotetic logics may differ in the class of sentences treated, the types of response counted as appropriate, the assignment of other content (presupposition, projection, etc.), and other details. See also DEONTIC LOGIC, EPIS- TEMIC LOGIC , MODAL LOGI. D.H.