ABSTRACT
Aristotle held that the object of knowledge cannot be other than it is; it must necessarily be true. Aristotle shared Plato's belief that knowledge must be of necessary and eternal truths. Aristotle's writings on logical subjects illustrate graphically his views on knowledge. According to Aristotle, the kind of argument that could produce conclusions that were certain was demonstration. This kind of argumentation came to be known as deduction or syllogistic argument. Validity is a crucial aspect of logical reasoning. It has a technical meaning in logic that is stricter than its common street meaning of true, right, and okay. In logic, validity is not the same as truth, but it is important in the demonstration of truth. The syllogism is based on categorical statements, which declare that a subject is a member of a class of things having a certain essential attribute. Aristotle does not base his logic on hypothetical or disjunctive statements.
