PHIL 2P25 Lecture Notes - Lecture 11: Jack Layton, First-Order Logic, Logical Form

• School: Brock University
• Department: Philosophy
• Course: PHIL 2P25
• Professor: Brian Lightbody

Document Summary

For an argument to have its conclusion accepted then it must have true premises, but valid arguments are more than that, as illustrated by the following example. No ndp leader has been elected as prime minister. Jack layton was not elected as prime minister. Even though all three are true, we have not been given good reason to accept the conclusion. It is not good reasoning if we can accept the premises and still deny the truth of the conclusion. An argument or inference is valid if and only if denying its conclusion is incompatible with accepting all its premises. Two statements are logically inconsistent if there is a logical contradiction between them. The second example requires knowledge of circles and squares whereas the first does not. In addition to valid reason, its premises must be true for an argument to be accepted. An argument is sound only if it is valid and all its premises are true.