PHL245H1 Chapter : Logic Unit 3 Part 1.pdf
Document Summary
A derivation is a proof or demonstration that shows how a sentence or sentences can be derived (obtained by making valid inferences) from a set of sentences. A derivation can be used to demonstrate that an argument is valid; that a sentence is a tautology or that a set of sentences is inconsistent. In a derivation, you are proving that the conclusion logically follows from the premises. We"ll be using a natural deduction system for first-order logic that uses the symbolic language that we have learned. Every sentence that is logically entailed by a set of sentences can be derived from that set of sentences using our derivation system the system is complete. Every one of the infinite number of valid theorems and valid arguments (within the scope of first-order sentential logic) can be proven. Every argument arrived at through our sentential derivation system will be deductively valid our system is consistent.
