NAÏVE VALIDITY

A naive validity theory can formally express its own notion of logical consequence. To block the inevitable Curry paradox, it is well known that a logic without the metarule of contraction will suffice. However, there ought to be a reason, independent of merely blocking paradoxes, to suppose that contraction fails. In this paper I provide such an argument, showing that naive validity has both explanatory and expressive roles—local and global dimensions, that make it naturally unfit for contraction.