logic

1. CATEGORICAL PREPOSITION AND CLASSES

10. RULES AND FALLACIES GROUP MEMBERS: FARYAL PERVEZ AYESHA MUNEER ANUM GUL

11. CATEGORICAL SYLLOGISM: A categorical syllogism is a formal deductive argument consisting of three statements TERMS: MIDDLE TERM: It is a term that occurs in both premises and does not occur in conclusion.

12. : THREE TERMS MAJOR TERM : Major term is the predicate of the conclusion. MINOR TERM: Minor term is the subject of the conclusion. EXAMPLE: No homework is fun ……… major premise Some reading is homework ……… minor premise Some reading is not fun………. Conclusion

13. DISTRIBUTION OF TERMS : A categorical term is said to distributed if all individual members of that category are accounted. There are four categorical propositions that distribute there terms. A, E I,O are the standard names for type of statement indicated STATEMENT TYPE TERM DISTRIBUTED A: All X are Y subject E: No X are Y subject, predicate I: some X are Y none O: some X are not Y predicate

14. RULES AND FALLACIES : Valid syllogism conforms to certain rules which if violated, a specific “Formal Fallacy “ is committed and the syllogism becomes invalid RULES: There are six rules for standard form syllogisms which are presented follows:

15. RULE NO: 1 RULE: A valid standard-form categorical syllogism must contain exactly three terms, each of which is used in the same sense throughout the argument. FALLACY: FALLACY OF FOUR TERMS

17. RULE NO :2 RULE: In a valid standard form categorical syllogism the middle term must be distributed at least once. FALLACY: Undistributed middle

18. EXAMPLE : All sharks are fish. All salmon are fish All salmon are sharks. In this syllogism the middle term is “fish”. In both premises “fish” occurs as the predicate of an A proposition and therefore it is not distributed in either premises. Thus syllogism commits the fallacy of undistributed middle.

19. RULE NO : 3 RULE: If a term is distributed in the conclusion, then it must be distributed in a premise. FALLACY: Illicit major ; illicit minor

20. EXAMPLES: All horses are animals Some dogs are not horses Some dogs are not animals In this example there is fallacy of “illicit major.” All tigers are mammals All mammals are animals All animals are tigers In this example there is fallacy of “illicit minor.”

21. RULE NO :4 RULE: In a categorical syllogism, two negative premises are not allowed FALLACY: Exclusive premises

22. EXAMPLE: No fish are mammals. Some dogs are not fish. Some dogs are not mammals. This syllogism is invalid because it has two negative premises and because of that it commit the fallacy of exclusive premises.

23. RULE NO:5 RULE: A negative premise requires a negative conclusion, and a negative conclusion requires a negative premise. FALLACY: Drawing an affirmative conclusion from negative premise or drawing a negative conclusion from affirmative premises.

24. EXAMPLE: All crows are birds Some wolves are not crows Some wolves are birds All triangles are three angled polygon All three angled polygons are three sided polygons Some three sided polygons are not triangles Both are invalid because 1st draws an affirmative conclusion from a negative premise. And 2nd draws negative conclusion from affirmative premises

25. RULE NO :6 RULE: If both premises are universal, the conclusion cannot be particular. FALLACY: Existential fallacy.

26. EXAMPLE : All mammals are animals All unicorns are mammals Some unicorns are animals. This syllogism is invalid because in this case the conclusion is EXISTENTIAL i-e Beginning with ‘Some’.

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