The task of logic is to study the principles underlying the validity deductive arguments and the strength of inductive arguments.

Since not all deductive argument are valid, we need to know the principles that ensures a valid argument to be valid and in valid argument to be invalid. It has been suggested that the arguments that satisfy or conform to the laws or principles of logic are valid and arguments that do not do so are invalid. In other won validity amounts to not violating any law of logic.

Logic deals with these principles and also we their interrelation. Out of the various laws of logic there exists three fundamental principle namely, (I) the law of identity, (ii) the law of contradiction (or the law of non-contradiction) are the law of excluded middle.

These are known as the laws of thought or fundamental principles logic. In calling these as laws of thought, there is a danger of interpreting them as psychological laws concerning mental processes of thinking. This would be a misunderstanding of their true nature. These are not descriptive laws. They do not tell us how people think. Rather these are prescriptive in nature. They tell us how one should think or, more precisely, how one should reason. So instead of calling them laws of thought, it is better to call them principles of logic.


These three laws are considered as fundamental or basic in the sense that any correct or good argument must conform to these laws. This means that these laws are presuppositions of a good argument.