Christ is a walking contradiction. He is both fully human and fully divine. Indeed, he is both mutable and immutable. According to classical logic, the existence of a true contradiction would imply that everything is the case, no matter how absurd. And so, theologians and Christian metaphysicians have worked for centuries to conceptually make sense of Christ’s dual nature in a way that avoids contradiction.
Philosopher and logician Jc Beall argues that these efforts have been motivated by a naive understanding of logic. There are “subclassical” logics – that is, logics weaker than classical logic – in which contradictions do not entail every arbitrary conclusion. And these aren’t ad-hoc constructions. Beall argues that one subclassical logic – called First Degree Entailment (FDE) – is, in fact, the correct account of logical consequence, for reasons independent of the Christian problem. Beall covers the basics of how FDE works and why it is the universal or “basement-level” consequence relation. This allows us to have our cake and eat it too: we may take Christ to be, quite literally, both mutable and not mutable, at the same time and in the same respect. This isn’t just appealing for its simplicity. Beall suspects that it is essential to Christ’s role that he be literally contradictory.