Aristotle defines artistic proofs (invention) to be within the scope of the art of rhetoric, and inartistic proofs (testimony) to be outside the art of rhetoric.
Aristotle’s was the first attempt to separate the art of argument from evidence and facts. He was the first to realize that a collection of facts (inartistic proofs) is just a collection of facts. It takes a skilled rhetorician to study those facts and bring them together in a composition that is interesting, persuasive, and useful to others.
There are, according to Aristotle, five types of inartistic proofs: laws, contracts, witnesses, tortures, and oaths. Today we would ethically eliminate tortures, and add to Aristotle’s list—from our technology-driven world—photographs, video clips, Gallup polls, and scientific experimentation. Inartistic proofs should never comprise the bulk of your essay, they are merely the raw materials from which your essay will be constructed.