  We combine linear temporal logic (with both past and future modalities) with
a deontic version of justification logic to provide a framework for reasoning
about time and epistemic and normative reasons. In addition to temporal
modalities, the resulting logic contains two kinds of justification assertions:
epistemic justification assertions and deontic justification assertions. The
former presents justification for the agent's knowledge and the latter gives
reasons for why a proposition is obligatory. We present two kinds of semantics
for the logic: one based on Fitting models and the other based on neighborhood
models. The use of neighborhood semantics enables us to define the dual of
deontic justification assertions properly, which corresponds to the notion of
permission in deontic logic. We then establish the soundness and completeness
of an axiom system of the logic with respect to these semantics. Further, we
formalize the Protagoras versus Euathlus paradox in this logic and present a
precise analysis of the paradox, and also briefly discuss Leibniz's solution.
