  In this paper, we address the logic of knowing why, an example of a
non-standard epistemic logic dealing with justified knowledge via a new
epistemic operator, under the extensions with ideas from dynamic epistemic
logic, namely public announcements. Through the additional notions present in
the knowing why context, we consider two possible variants, namely the
extensions by (i): public announcements of a formula and by (ii): public
announcements of reasons, although the deeper analysis of the latter is left
for future work. We consider another logical operator, the conditional
knowing-why operator, for which we study the applications to the axiomatization
of public announcements as well as the solely framework. At the end, we
consider the logical expressivity of these different logics in comparison to
each other, and thus we show one of the main problems with the usual process of
proving completeness through translation in the context of logics with public
announcements.
