PHLA10H3 Lecture 3: Lecture 3 Notes
Document Summary
In the land of the knights and knaves. A says "at least one of use us a knave". You meet two individuals , a and b. A says "either i am a knave or b is a knight" A sound argument cannot have a false conclusion. An invalid argument can have a false conclusion. Deductive arguments - conditionals: x > y, x; therefore y (valid, x > y, y; therefore x (invalid, x > y, not-x; therefore not-y (invalid, x > y, not-y; therefore not-x (valid) Necessary and sufficient conditions: given if x then y, x is a sufficient condition for y, given if x then y, y is a necessary condition for x. Correspondence: a sentence is true if it corresponds to reality. Coherence the biggest collection of statements that are all true together. "snow is white" is true says just "snow is white"
