Media Argumentation by Douglas Walton | Excerpt

The following excerpt about evaluating appeals to expert opinion (aka appeal to authority) is from Professor Douglas Walton's Media Argumentation: Dialectic, Persuasion, and Rhetoric.

[I]n court, a ballistics expert may be called in as a witness to testify about a bullet found at a crime scene. The first component of the argumentation scheme for argument from expert opinion is the following form