What is logic?

by Matt Slick

Logic is the process of proper inference.  It is the system of thinking properly, of arriving at proper conclusions.  It is the process of proper thinking based upon principles that govern the validity of arguments.

The first law of logic is the Law of Identity.  It states that something is what it is, and is not what it is not.  For example, a rock is a rock and not a frog.

The second law of logic is the Law of Non-Contradiction.  This means that something cannot be both true and false at the same time and in the same way.  In other words, two contradictory statements cannot both be true.

The third law of logic is the Law of Excluded Middle, which says that a statement is either true or false.  “We are here” is a true statement.  “The planet Mars is in my pocket” is not a true statement.