ABSTRACT
All of Part II of this book is devoted to deductive arguments. A deductive argument is one whose premises are claimed to provide conclusive grounds for the truth of its conclusion. If that claim is correct-that is, if the premises of the argument really do assure the truth of its conclusion with necessity-that deductive argument is valid. Every deductive argument either does what it claims, or it does not; therefore, every deductive argument is either valid or invalid. If it is valid, it is impossible for its premises to be true without its conclusion also being true.
