Chapter 6.4 Notes PDF

Preview

Summary

Chapter 6.4 Notes Fall 2018...

Description

6.4 Truth Tables for Arguments ●

●

Truth tables can be used for evaluating validity/invalidity of arguments! ○ Can prove that an argument is invalid (presence of a counter example) ○ Can prove that an argument is valid (absence of any possible counter example) Validity ○ If premises are true, then conclusion must be true ○ (premise true but conclusion false = invalid, prove that use counter example method)

Finding counter example with truth table ● Symbolize the argument (make sure to use letters to represent the simple propositions) ● Write out the symbolized argument; place a single slash between the premises and a double slash between the last premise and the conclusion ● Draw a truth table for the symbolized argument (compute the possible truth values for the premises and the conclusion) ● Look for a line in which all of the premises are true and the conclusion is false. If such a line exists, the argument is invalid (aka theres a counter example) If not, it is valid...