AbstractInquisitive first order logic "Equation missing" is an extension of first order classical logic, introducing questions and studying the logical relations between questions and quantifiers. It is not known whether "Equation missing" is recursively axiomatizable, even though an axiomatization has been found for fragments of the logic (Ciardelli, 2016). In this paper we define the $$\mathsf {ClAnt}$$ ClAnt —classical antecedent—fragment, together with an axiomatization and a proof of its strong completeness. This result extends the ones presented in the literature and introduces a new approach to study the axiomatization problem for fragments of the logic.