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Introduction to Toulmin Logic. Scott Hale English 1213.005. Logos. What do we mean by “logical structure?” Chain of Reasoning and Support. Formal Logic vs. The REAL World. Formal Logic. Operates according to prescribed values and methods IF q=r AND r=t THEN q=t. REAL World.

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Introduction to Toulmin Logic

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Introduction to Toulmin Logic

Scott Hale

English 1213.005

Logos

• What do we mean by “logical structure?”

• Chain of Reasoning and Support

Formal Logic

• Operates according to prescribed values and methods

• IF q=r

• AND r=t

• THEN q=t

REAL World

• Prescribed rules and methods fail...

• IF bad students fail classes

• AND John fails a class

• THEN John is a bad student?

The Difference?

• Formal Logic=universal abstractions

• REAL World=specific actualities

• Formal Logic=SYLLOGISM

• REAL World=ENTHYMEME

SYLLOGISM...

• Aristotle called a “complete logical structure”

• Three parts:

• Specific Premise

• General Premise

• Conclusion

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…

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

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)

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

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

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)

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

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)

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

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

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

Examples…

• Some dogs are red

• Only when he is sunburned is Fred red

• Unless it is Friday, I am going to study tonight