Deductive arguments do not depend upon their specific content, but on theirform or structure. It is valid becauseof the form, and this means that every argument with this form will bea logically valid argument. Furthermore, if the premises ofsuch an argument are true, then the argument is a sound argument, i.e.,the conclusion is necessarily true. Categorical logic has existed forover two thousand years, since first developed by Aristotle. It isalso referred to by the terms traditional, Aristotelian, and syllogistic logic .
Categorical logic is primarily concernedwith categorical claims.
Categorical claims assert or deny relationshipsbetween terms or classes. The term Californians is said to be the subject term, and the term Americansis said to be the predicate term of the categorical claim All Californiansare Americans. Each of these forms of claims can be givena visual illustration in a Venn Diagram . In each Venndiagram , the two overlapping circles represent the groups or categoriesnamed by the subject and predicate term. Opposite to what youmay have experienced in illustrating sets in math class, a shaded arearepresents an empty class .