Introduction to Toulmin Logic

1. Introduction to Toulmin Logic Scott Hale English 1213.005

2. Logos • What do we mean by “logical structure?” • Chain of Reasoning and Support

3. Formal Logic vs. The REAL World...

4. Formal Logic • Operates according to prescribed values and methods • IF q=r • AND r=t • THEN q=t

5. REAL World • Prescribed rules and methods fail... • IF bad students fail classes • AND John fails a class • THEN John is a bad student?

6. The Difference? • Formal Logic=universal abstractions • REAL World=specific actualities • Formal Logic=SYLLOGISM • REAL World=ENTHYMEME

7. SYLLOGISM... • Aristotle called a “complete logical structure” • Three parts: • Specific Premise • General Premise • Conclusion

8. Example... • Fred is a dog • Dogs are red • Therefore… • Fred is red • Syllogisms provide the specific and general premises and ask the audience to supply the conclusion…

9. But what happens if…? • You’re given the conclusion and one of the premises… • Socrates is mortal • Socrates is human • What’s missing? • The general premise... • Humans are mortal

10. ENTHYMEME • Aristotle called an “incomplete logical structure” • The enthymeme consists of a claim (conclusion) and a reason (suggests the specificpremise) • All enthymemes then hinge upon an unstated assumption (generalpremise)

11. Example… • Fred is red because he is a dog… • Claim/Conclusion=Fred is a red • Reason/Suggests Specific premise=Fred is a dog • Assumption/General premise=Dogs are Red

12. Toulmin Logic • A method for the construction and analysis of arguments • Builds upon the enthymeme by supplying the unstated assumption/general premise • Calls the assumption into question by requiring support for it

13. Toulmin Terms: • Claim (conclusion) • Reason (support/explanation for conclusion) • Grounds (specific premise) • Evidence (support for Grounds) • Warrant (unstated assumption/general premise) • Backing (support for warrant)

14. Developing the Toulmin schema • Develop enthymeme (Claim and Reason) • To develop Grounds: Link Subject of Claim to Predicate of Reason • To develop Warrant: Link Category of Predicate of Reason to Predicate of Claim

15. Example... • Enthymerme: Fred is red because he is a dog • Claim: Fred is red • Reason: because he is a dog • Grounds: Fredis a dog (specific premise) • Warrant: Dogs are red (general premise)

16. Evidence and Backing • Evidence supports the Grounds (specific premise) and will always directly refer to the subject • Backing supports the Warrant (general premise) and will never refer directly to the subject, but instead to the category of the subject

17. Example… • C: Fred is red • R: b/c he is a dog • G: Fredis a dog • Evidence: Support that Fredis a dog--expert testimony, data, etc • W: Dogs are red • B: Support that Dogs are red--expert testimony, data, other examples

18. Qualifiers • A qualifier limits the force of a claim by pointing to any exceptions to a rule and indicating how the condition would have to change in order for the understanding (epistemology) to change

19. Examples… • Some dogs are red • Only when he is sunburned is Fred red • Unless it is Friday, I am going to study tonight