 Other structural rules are also a called into question. Another possible application of substructural logic is found in the analysis of paradoxes such as  Curry’s paradox.  A crucial move in the reasoning in Curry’s paradox and other paradoxes like it seems to require the step reducing two applications of an assumption to a single one (which is then discharged). According to some, this step is problematic, and so, they must distinguish an argument from \(A\) to \(B\) and an argument from \(A, A\) to \(B\). The rule of contraction is rejected.