A common extension to the standard formal languages outlined above is to introduce the technical machinery required to evaluate natural language arguments containing modal terminology (that is, talk of possibility…

The language sketched above is better referred to as first-order predicate calculus, as the language only quantifies over (first-order) individuals. A stronger language, second-order predicate calculus, can therefore be constructed…

A relevance logic is motivated by the idea that the premises of a valid argument must be somehow “relevant” to its conclusion. The idea is motivated by the fact that…

Most non-classical logics are motivated by either philosophical considerations, such as the metaphysical status of the future, or technical concerns about the neutrality of the logical connectives or the notion…