  The study of defeasible reasoning unites epistemologists with those working
in AI, in part, because both are interested in epistemic rationality. While it
is traditionally thought to govern the formation and (with)holding of beliefs,
epistemic rationality may also apply to the interrogative attitudes associated
with our core epistemic practice of inquiry, such as wondering, investigating,
and curiosity. Since generally intelligent systems should be capable of
rational inquiry, AI researchers have a natural interest in the norms that
govern interrogative attitudes. Following its recent coinage, we use the term
"zetetic" to refer to the properties and norms associated with the capacity to
inquire. In this paper, we argue that zetetic norms can be modeled via
defeasible inferences to and from questions---a.k.a erotetic inferences---in a
manner similar to the way norms of epistemic rationality are represented by
defeasible inference rules. We offer a sequent calculus that accommodates the
unique features of "erotetic defeat" and that exhibits the computational
properties needed to inform the design of zetetic agents. The calculus
presented here is an improved version of the one presented in Millson (2019),
extended to cover a new class of defeasible erotetic inferences.
