I teach Intro to Logic, and Philosophy of Religion. I started off Logic by giving some basics. Here they are.
Logic, in philosophy, is about the making and evaluating of arguments.
An argument has one (and only one) conclusion, and one or more supporting premises.
The conclusion and premises need to be statements, also called propositions. A statement is a sentence that is either true or false. Aren't all sentences either true or false? No - many sentences have no cognitive value. such as, for example, requests. If I'm at your home for dinner and request of you, "Please pass the salt," your response should not be: "True." Requests are neither true nor false. That I made a request can be either true or false, but ot the request itself, as stated.
If a statement is true, it is true for everybody; if it is false, it is false for everybody. For example, consider the statement: The lights in this room are on. If that statement is true, it is true for everybody. Or, consider this statement: I think the lights in this room are on. If true, it's true for everybody; viz., it is true that I think the lights in this room are on.
Try this statement: God exists. If that statement is true, it is true for everybody, and atheists are wrong. If it is false, then it is false for everybody, and theists are wrong. Such is the logical character of statements.
This is a hard one for a lot of students, who are relativists at heart (and unreflectively so). So I give another, easier-to-see example. The temPerature outside is now 70 degrees F. This statement is either T or F. If T, then (isn't this obvious?) it is T for everyone. If F, then it is F for everyone. What if someone says, For me the temperature is 71 degrees F. That statement, if it expresses a truth about the person uttering it, is true, and true for everyone. It changes nothing about the statement The temperature is 71 degrees F.
Logic has no necessary connection with the disciplines of psychology, sociology, or anthropology. The truth or falsity of a statement has nothing to do with issues like what a person believes, how they were raised, where they were raised, how many believe certain things, and so on.
Thus Logic is the philosophical tool for discovering truth.
