What are the basic principles of logic?

1. The Law of Identity
2. The Law of Non-Contradiction
3. The Law of Excluded Middle

1. The law of identity says that A is A, that if something exist it has a nature, a single nature. It is what it is.
2. The law of non-contradiction says that A cannot be both A and not A at the same time and in the same sense. Truth is not self-contradictory.
3. The law of excluded middle says that a statement is either true or false.