PHL245H1 Lecture Notes - Lecture 1: Propositional Calculus, Atomic Sentence, Deductive Reasoning
Document Summary
Statements are sentences that are true or false. Type of arguments: deductive arguments are certain (from general to specific) Inductive arguments are fallible (from specific to general) Two senses of good are valid and sound. Wherever the premises are true, the conclusion must be true. It is impossible for the premises to be true and the conclusion to be false. Validity is not about content and truth; it is all about form and structure. It is possible for the premises to be true and the conclusion to be false. It is valid: all the premises are true. Soundness is about content, truth, form and structure. If it is raining, then the sidewalk is wet. However, there could be a tree on the sidewalk to make the premises not always true. Inductive arguments are not valid or sound, but they are strong or cogent. Cogent inductive arguments can have a false conclusion. This swan is white; this other swan is white.
