Abstract

According to the Asymmetry Thesis, whereas there are many kinds of argument-forms that make at least some of their instances valid, there is none that makes any of its instances invalid. To refute this thesis, a counterexample has been produced in the form of an argument-form whose premise-form's instances are all logically true and whose conclusion form's instances are all logically false. The purpose of this paper is to show that there are many more kinds of argument-forms that make some of their instances invalid and that, hence, are counterexamples refuting the Asymmetry Thesis