To evaluate an enthymeme in a categorical syllogism we must: o Identify the missing step It could be a major/minor premise or conclusion o Put the syllogism into standard form o Apply the Venn Diagram method
When choosing how to include the missing step, always include the one that'll produce the most validly possible argument considering the content given 6.6: Sorites and Removing Term-Complements Sorites : a chain of syllogisms in which the final conclusion is stated but the subconclusions are unstated o A "heap" of syllogisms o Easiest to identify in its standard form, which includes these features: i. Each statement in the argument is in standard form ii. The predicate term of the conclusion occurs in the first premise iii. Each term appears twice, in two different statements iv. Each premise has a term in common with the immediately preceding premise o Evaluate a sorite: i. Check to see if the sorites is in standard form. If it is, proceed to the next step; if it isn't, put it into standard form. ii. Identify the subconclusions. iii. Test each syllogism in the chain for validity, using Venn diagram. If each syllogism in the chain is valid, the sorites is valid; if any of the syllogisms in the chain are invalid , the entire sorites is invalid. o State the subconclusions next to the last premise that validates that subconclusion Removing Term-Complements o We can often reduce the number of terms by applying conversions, obversions, or contrapositions to arguments involving term-complements o We are free to remove term-complements as long as the changes we make to each statement produces a logically equivalent statement o Only these permissible changes are allowed as follows: Conversion: No S are P.
- Fall '08
- Logic, Standard form, Syllogism, Traditional logic, categorical syllogism