Presentation on theme: "-- in other words, logic is"— Presentation transcript:
1-- in other words, logic is i.e. the study of argumentand the use of reason-- in other words, logic isthe study of thinking
2Logic:differs from Psychologydoes not deal with allmental phenomena (learning,remembering, daydreaming,etc.), but only with that typeof thinking called “reasoning.”
3Logicis not concerned withemotional states at all, orwith the “inner processes”going on in the mind of thethinker.
4Logicis concerned only withreasoning itself, and theformulation of rules that willhelp us determine if anyparticular piece of reasoningis logical; i.e. coherent andconsistent.
5The Structure of Argument The basic unit of logic is theproposition or statement,typically expressed in adeclarative sentence:e.g. “Smith loves Jones.”“Socrates is mortal.”
6The Structure of Argument The key characteristic of eachproposition is that it can beeither true or false, but notboth.e.g. Either “Socrates is a man”is true, or “Socrates is not aman” is true -- but not both.
7The Structure of Argument The chief concern of logic ishow the truth of somepropositions (premises) isconnected with the truth ofanother (the conclusion).
8The Structure of Argument For example:All men are mortal. (premise)Socrates is a man. (premise)Socrates is mortal. (conclusion)
9The Structure of Argument The pattern of logic that letsus connect these premises toarrive at the conclusion wecall an inference.
10The Structure of Argument Without this pattern ofinference, we have merely acollection of disjointedpropositions.e.g.“My dog has fleas.”“The moon is made of cheese.”“Strawberries are red.”
11The Structure of Argument Our primary concern is toevaluate the reliability ofinferences, the patterns ofreasoning that lead frompremises to conclusion in avalid argument.