Existential import in logic
Download as PPTX, PDF4 likes2,642 views
The document discusses different aspects of existential import in logic. It defines existential import as a statement having truth dependent on evidence for things in certain categories referenced by the statement's subject and predicate terms. It provides examples to illustrate formal vs material import, bivalence logic, traditional syllogistic views, developments during the golden age of logic with thinkers like Boole, Frege, and Russell, Fred Sommers' discussion of Strawson on existential import and truth-value gaps, and defines material implication as the relationship between an antecedent and consequent in conditional statements.
Existential import in logic
- 1. عور ُ شجوسے نام پاککے ہلل َ انہا بانمہر بڑایت ۔ ےہ واال حمر ِن ٰحمَّالر ِہللا ِسمِباِحَّلریم
- 2. Group # 9 Danish Raza 13170920-072 Ali Asghar 14220920-017
- 4. A statement has existential import when its truth depends on evidence for the existence of things in a certain category--in the case of categorical propositions, the existence of things in the categories signified by its subject and predicate terms.
- 5. Example: 1: All buttercups are blue Blue buttercups exist 2: Some dragons are fire-breathing fire-breathing dragons exist
- 6. Different forms of Existential Import Formal & Material Import Bivalence Import Traditional Views The Golden Age of Logic Fred Sommer and Existential Import Material Implication
- 7. Formal & Material Import Formal The structure of arguments in order to see how reasoning proceeds from premises to a conclusion. Material It does not deal with the form or structure of arguments, but rather with their content. While formal logic deals with how you get from one truth to another.
- 8. Example All men are mortal Socrates is a man Therefore, Socrates is mortal
- 9. Bivelence Logic logic philosophy the semantic principle that there are exactly two truth values, so that every meaningful statement is either true or false. Example T & T =T F & T= F T & F= F F &F= T
- 10. Traditional Views Traditional logic involves mostly the study of the classical syllogism. Example Murder is wrong. Some times murder is not wrong. Therefore murder is always wrong.
- 11. The Golden Age of Logic The golden age of logic occurred during the 19th century, when such giants as Boole, ideal precisely because there are none who fit the ideal, Example “perfect men do not break the rules.” This does not imply that even if a man were to refrain from breaking the rules, that perfect men actually exist.
- 12. It is ideal precisely for that reason. Venn says, however, that in popular usage we do not “without warning” make predicates of non-existence subjects.
- 13. Fred Sommers and Existential Import Fred Sommers discussed P. F. Strawson’s attempt to use “truth-value gaps” as a way of interpreting such expressions as, (1) “the present king of France is bald.” The “present king of France” has no existence, so under Russell’s view of existential import,
- 14. The proposition would be false merely because its subject term was vacuous Russell regarded the subject term as entailing that there was a present king of France and the proposition was false for that reason.
- 15. Material implication A conditional statement describes a relationship between the antecedent and the consequent. This relationship is called "material implication" Denoted by: “=>” or
- 16. For Example If you study hard, then you will pass. Antecedent Consequent => If p, then q.
- 17. Thank you