  Prawitz conjectured that the proof-theoretically valid logic is
intuitionistic logic. Recent work on proof-theoretic validity has disproven
this. In fact, it has been shown that proof-theoretic validity is not even
closed under substitution. In this paper, we make a minor modification to the
definition of proof-theoretic validity found in Prawitz (1973) and refined by
Schroeder-Heister (2006). We will call the new notion generalised
proof-theoretic validity and show that the logic of generalised proof-theoretic
validity is intuitionistic logic.
