PHIL 210 Lecture Notes - Lecture 14: Logical Consequence
21 Feb 2018
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Chapter 6 section 6. 3 : negation rules and the use of contradiction. Chapter 6 section 6. 5 : strategy on constructing proofs. Chapter 6 section 6. 6 : proofs without premises. We use two rules for it: an intro rule an elim rule. The normal use of this sign will be inside a subproof the main point is to be able to use negation introduction. Phil210 page 2 let us call a set of sentences gamma. Gamma is an inconsistent set of sentences if it is not possible for the sentences all to be true together note a set containing a contradictory sentence is automatically inconsistent consider an inconsistent gamma any sentence q and then. Avoid arguments with inconsistent premises if someone argues for q but uses inconsistent premises gamma then the argument is worthless because although q follows, so does not q the grounds given for q are not any good.
