Philosophy:Polysyllogism
A polysyllogism (also called multi-premise syllogism, sorites, climax, or gradatio) is a string of any number of propositions forming together a sequence of syllogisms such that the conclusion of each syllogism, together with the next proposition, is a premise for the next, and so on. Each constituent syllogism is called a prosyllogism except the last, because the conclusion of the last syllogism is not a premise for another syllogism.
Example
An example for a polysyllogism is:
- It is raining.
- If we go out while it is raining we will get wet.
- If we get wet, we will get cold.
- Therefore, if we go out we will get cold.
Examination of the structure of the argument reveals the following sequence of constituent (pro)syllogisms:
- It is raining.
- If we go out while it is raining we will get wet.
- Therefore, if we go out we will get wet.
- If we go out we will get wet.
- If we get wet, we will get cold.
- Therefore, if we go out we will get cold.
Sorites
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Look up sorites in Wiktionary, the free dictionary. |
A sorites (plural: sorites) is a specific kind of polysyllogism in which the predicate of each proposition is the subject of the next premise. Example:
- All lions are big cats.
- All big cats are predators.
- All predators are carnivores.
- Therefore, all lions are carnivores.
The word sorites /sɒˈraɪtiːz/ comes from Ancient Greek:, heaped up, from σωρός heap or pile. Thus a sorites is a heap of propositions chained together. A sorites polysyllogism should not be confused with the sorites paradox, a.k.a. the fallacy of the heap.
Lewis Carroll uses sorites in his book Symbolic Logic (1896). For example:[1]
- No experienced person is incompetent;
- Jenkins is always blundering;
- No competent person is always blundering.
- Jenkins is inexperienced.
Carroll's example may be translated thus:
- All experienced persons are competent persons.
- No competent persons are blunderers.
- Jenkins is a blunderer.
- Jenkins is not an experienced person.
See also
- Anadiplosis - the rhetorical grounds of polysyllogism.
- Transitive relation
- Type of syllogism (disjunctive, hypothetical, legal, poly-, prosleptic, quasi-, statistical)
Notes
- ↑ Lewis Carroll (1897). Symbolic Logic. Project Gutenberg. pp. 113. https://www.gutenberg.org/files/28696/28696-h/28696-h.htm.
Bibliography
- B. P. Bairan. An Introduction to Syllogistic Logic. Goodwill Trading. p. 342. ISBN 971-574-094-4.
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