ABSTRACT
Argumentation is one of the areas in which logic can be useful. Statements are the basic building blocks of arguments. Logical arguments do not necessarily involve any anger or feelings of any kind. Speakers and writers typically use indicator words. These make it clear that statements have been combined into a logical argument by marking the role of one or more of the statements. An argument may be: valid with true premises; valid with at least one false premise; invalid with true premises; or invalid with at least one false premise. Category a corresponds to sound arguments; categories a and b together are the valid arguments; categories c and d together are the invalid arguments; and categories b, c, and d together are the unsound arguments. Arguments in which one of the premises or the conclusion is not explicitly stated are called enthymemes.
