Conspiracy Theory
PWR 1, Spring 2008
Stanford University
Jonah Willihnganz

Figures of Reasoning

Generally speaking, formal argumentation proceeds via strict syllogisms (inferences), and proceeds via deduction or induction. Most reasoning we encounter in writing and speech, however, is not formal and relies on what rhetoricians call "figures of reasoning". By far the most common of these is the enthymeme, or "truncated syllogism", in which one of the premises that leads to the conclusion is simply assumed. There are a number of other figures of reasoning and the most common are listed here. This list is drawn from the Forest of Rhetoric and BYU and the deifinitions and examples are provided by the Forest of Rhetoric.

• enthymeme
  The informal method of reasoning typical of rhetorical discourse. A truncated syllogism.
• sorites
  A chain of claims and reasons which build upon one another. Concatenated enthymemes.
• syllogismus
  The use of a remark or an image which calls upon the audience to draw an obvious conclusion.
• aetiologia
  A figure of reasoning by which one attributes a cause for a statement or claim made.
• ratiocinatio
  Reasoning (typically with oneself) by asking questions.
• anthypophora
  A figure of reasoning in which one asks and then immediately answers one's own questions.
• apophasis
  The rejection of several reasons why a thing should or should not be done and affirming a single one, considered most valid.
• contrarium
  Juxtaposing two opposing statements in such a way as to prove the one from the other.
• expeditio
  After enumerating all possibilities by which something could have occurred, the speaker eliminates all but one.
• proecthesis
  When, in conclusion, a justifying reason is provided.
• prosapodosis
  Providing a reason for each division of a statement, the reasons usually following the statement in parallel fashion.
• paromologia
  Admitting a weaker point in order to make a stronger one.
• dirimens copulatio
  A figure by which one balances one statement with a contrary, qualifying statement
• commoratio
  Dwelling on or returning to one's strongest argument.