Toulmin Logic

Four Factors Claim (Thesis) Data (Evidence that specifically supports your thesis) Warrant (Assumptions your audience has) Backing (Evidence that specifically addresses those audience assumptions)

Typically, student writers will address the claim and the data Typically, student writers will address the claim and the data. But to make a fully developed persuasive argument, you need more than just facts. You need to address the ideas and beliefs your audience already has to build your argument.

Example If you present a well-informed and researched argument about the detrimental effects of global climate change and why it’s so significant, your argument will be completely ineffective if your audience believes (Assumption) that global climate change doesn’t exist.

Backing What evidence can you use to specifically address your audience’s assumption that global warming does not exist?

Example of claim with datum (singular version of “data”) Claim/Thesis: Alien abduction is a real phenomenon. Datum/Evidence: Many people who have been hypnotized recall alien abduction scenarios. Assumption: Backing: Based on the thesis and subsequent evidence, what ASSUMPTION did the writer make? • Assumption: Hypnosis is a valid means of recovering suppressed memories. • Why it’s important to address this Assumption: If the reader does not believe that hypnosis is a valid means of recovering suppressed memories, there is no way that he/she will believe anything else presented in the argument.

Identify Assumptions Claim: Bill is going to be a really good teacher. Datum: (Evidence): He really loves kids. Assumption: Backing:

Identify Assumptions Claim: Debbie is a liar. Data (Evidence): Debbie has told us ten things about the Johnson contract and all ten have turned out to be untrue. Assumption: Backing:

Identify Assumptions From Patricia Cornwell’s Portrait of a Killer: Jack the Ripper – Case Closed Cornwell’s central claim is that Jack the Ripper was really Walter Richard Sickert, a relatively well-known English painter of the late 19th Century.

Identify Assumptions Claim: Sickert was Jack the Ripper. Datum (Evidence): One of the letters that purported to be from Jack the Ripper was written on the same brand of stationery as a letter from Sickert. Assumption: Backing:

Identify Assumptions Claim: Sickert was Jack the Ripper. Data (Evidence): Sickert had an operation as a child that left him unable to have a normal sex life. We know today that many serial killers are impotent. Assumption: Backing:

Identify Assumptions Claim: Sickert was Jack the Ripper. Data (Evidence): Sickert painted a picture in 1908 called “Jack the Ripper’s Bedroom,” described by an art historian as being “very dark and disturbing.” Sickert often painted scenes of violence against women. Assumption: Backing: