PHIL 24320 Lecture Notes - Lecture 4: Validity
Document Summary
An argument is *logically valid if the move from the premise p to the conclusion q could never take you from truth to falsehood. If an argument is valid, it means that reasoning from those premises to the conclusion could never take you downhill. Validity is just a guarantee that you won"t go downhill in your reasoning. The conclusion cannot be false if the premises are true. It has to be a necessary truth, where there"s no way that it could ever be false, no matter the circumstances. Not valid: the professor always brings coffee to class; therefore, he brought coffee to class today. Not valid because it could be possible that he was running late today so he couldn"t get coffee. This would happen when the premises couldn"t possibly all be true (because could change the conclusion to something false and the argument can"t be valid if all of the premises are true and the conclusion is false).
