PHIL 110 Lecture Notes - Lecture 7: Truth Table, Counterexample
16 Mar 2017
School
Department
Course
Professor
Document Summary
Dr mc"s philosophy 110 (1171), part notes 4#2 . Every substitution instance of a tautologous sentence form is true. Every sentence form that a tautologous sentence is a substitution instance of is a tautologous sentence form. Tautologous sentence forms have nothing but ts in the column for the main connective. Some sentence forms have f" on every line of the column for the main connective. Logic tells us sentences of these forms must be false. p | p ~p. These forms are contradictory form and any sentences that are substitution instances of them are contradictory. Some sentence forms have mixed bag in the main connective column. Logic alone does not determine that that a particular substitution instance is true or not. However, whether a sentence is contingent or not depends on what its one-one form is. These are logically equivalent the truth tables for their forms are identical in the main column.
