Bilateralism and invalidities.

There are many ways of understanding what it is for an argument to be valid. Although we usually identify the concept of validity with (classical first-order) logical validity and, in turn, we typically take this to capture the notion of necessary preservation of truth in virtue of logical form, this is just one way in which validity can be explained. A different understanding of the notion of validity that has received some attention recently is based on the idea that an argument is valid just in case accepting its premises is incoherent with rejecting its conclusion. The main claim of the paper will be that, under this understanding of the notion of validity, the usual reasons to privilege a treatment of validities over a treatment of invalidities loose much of their force. Validity and invalidity are on a par, which means that there are no strong reasons to treat validities primitively and to define invalidities in terms of them. [ABSTRACT FROM AUTHOR]