  Causal loops, e.g., in time travel, come with two main problems. Most
prominently, the grandfather antinomy describes the potentiality to
inconsistencies: a problem of logical nature. The other problem is called
information antinomy and is lesser known. Yet, it describes a variant of the
former: There are not too few consistent solutions -- namely none -- but too
many. At a first glance, the information antinomy does not seem as problematic
as the grandfather antinomy, because there is no apparent logical
contradiction. In this work we show that, however, both problems are equivalent
under interventions: If parties can intervene in such a way that the
information antinomy arises, then they can also intervene to generate a
contradiction, and vice versa.
