If an argument is sound, then its conclusion is true and (assuming that you know the argument is sound) you must believe the conclusion. Knowing whether an argument is sound is much more difficult than knowing if it is valid. To test an argument for validity, one need only inspect the form of the argument. To test an argument for soundness, one must evaluate whether the premises are true. Sometimes that is not too difficult, but often it is very difficult. As a discipline, logic is mostly concerned