PHIL 109 Lecture Notes - Lecture 11: Syllogism, Informal Logic

• School: Marymount
• Department: Philosophy
• Course: PHIL 109
• Professor: Carrie-Anne Biondi

Document Summary

Study questions for chapters 5-6 were graded and redistributed to students. Exercises 6. 1a and 6. 1b were completed in class. Square of opposition exercises distributed and partially completed in class. Informal logic: trying to establish that the conclusion is probably true. Formal logic: trying to establish that the conclusion is absolutely true. Categorical syllogism: a syllogism made up of all categorical propositions. A copula (conjugated form of to be ) The different variables above can create four different categorical propositions (a,e,i, and o). It should be noted that the some we talk about in i and o means at least. The square of opposition shows the relationship between a, e, i, and o propositions (see above) A & e have a contrary relationship. Both propositions cannot be true, but both propositions can be false. A & o and e & i have a contradictory relationship. Both propositions cannot be true or false; they are always opposites.