Law of the excluded middle

The law of the excluded middle is a simple rule of logic. It states that for any proposition, there is no middle ground. Every proposition is either true or false.
Example.
For example, "Ginger is a cat" says the fact that Ginger is a cat. If it is true, then its opposite cannot also be true. If Ginger is a cat, then Ginger is not something else.
Mathematics.
In mathematics, the law of the excluded middle is a presupposition behind the proof by contradiction. Because of that, those who reject the validity of the law of the excluded middle (for example, the intuitionists) must also reject the validity of proof by contradiction as well.