COMM 1117 Lecture Notes - Lecture 13: Stephen Toulmin
2 May 2018
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Informal Validity [RSP 58]
1. Patterns by which some statements (claims) are supported by other statements (grounds,
warrants, backing) (Toulmin model).
• Claim is affected by other aspects that is why you identify the claim first (look at how
everything is arranged)
2. This kind of validity depends on the arrangement, content, and meanings of a set of
statements/ words
Validity in the Toulmin Model
1. If the claim IS supported by the grounds, warrants, and backing, it is valid.
2. If the claim is NOT supported by the grounds, warrants, and backing, it is invalid.
• Validity in the Toulmin model emphasizes the types of warrants and the forms of
support needed for them
Formal Validity [RSP 57]
1. Pattern of formal relations by which statements (premises) can be combined to yield other
statements (conclusions).
2. This kind of validity depends on the arrangement or distribution of terms in a set of
statements (a logic).
3. Some situations in which arrangement of terms matters:
a) Equations in mathematics
EX) A (b + 1) = 3 not equivalent to ab+ 1=3 for values other than a = 1 and b = 2
Computer programs require that statements be placed in a certain order or they will
not run
b. Grammar
EX) Throw the horse over the fence to some hay.
Throw some hay over the fence to the horse.
Throw some hay to the horse over the fence.
• Changing the order changes the meaning
4. Formal logic is useful for ordinary argument as a way to organizing claims and grounds about
qualities possessed by people or things. Predication connects particulars to categories.
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