This talk will detail how a language I have formalised, MeDeTy, has an unsound type system. I will do this by showing how its type system allows the encoding of first order logic. Although most of the type system is non novel, it is the unique features of MeDeTy that allow the encoding of FOL relation symbols that leads to unsoundness, in particular I show how to encode Rusell and Curry’s famous paradoxes. However, this unsoundness only occurs if the user defines a logically inconsistent relation, and I explain how to formalise this result.