[Revised entry by Jc Beall, Greg Restall, and Gil Sagi on May 17, 2024. Changes to: Bibliography, local.js] A good argument is one whose conclusions follow from its premises; its conclusions are consequences of its premises. But in what sense do conclusions follow from premises? What is it for a conclusion to be a consequence of premises? Those questions, in many respects, are at the heart of logic (as a philosophical discipline). Consider the following argument:...