Philosophy 2250 Lecture Notes - Logical Biconditional

• School: Western University
• Department: Philosophy
• Course: Philosophy 2250
• Professor: Lorne Falkenstein

Document Summary

6. ((a=~a) v ~b) add outer brackets. 7. (a=~a) v ~b drop outer brackets. A, a, b are sentence letters by sl. ~a and ~b are sentences by ~ rule. (~a v ~b) is a sentence by bc rule. (a= (~a v ~b)) 1,4, bc rule. *do not apply parentheses when using ~ rule. *meta-variables are boldfaced letters that are meant to represent sentences of sl that could be atomic, binary or even more complicated. Whatever the last connective is when you build the sentence is the main connective. To improve the appearance of a sentence we adopt two conventions: (op) first, we will drop the outermost parentheses. May only be dropped if they are really outer: ([) second, we will allow brackets (i. e. , [ and ] ) to be substituted for parentheses. Brackets should be understood as parentheses, and outer parentheses should be understood to be there even if they are not written down.