Parol Evidence Rule says that if a written contract is a complete and final statement of the parties' agreement, any prior or comtemporaneous oral or written statements that alter, contradict, or are in addition to the terms of the written contract are inadmissable in court regarding a dispute over the contract.
Basically, what is being said here is that "a written contract is viewed as the best evidence of the terms that the parties agreed to", and the courts will not allow the use of extrensic documents in a dispute over the terms of the contract. The contract stands on its own, up to the court's intrepretation.
what is your opinon (300+words)
The Parol Evidence Rule makes sure that somebody does not try to circumvent the legal contract system to their own favor by doing something when the contract is formed in order to alter the conditions of the contract later on. In this case a person can agree on paper to one thing but then agree orally to something else. Later on, if something changes, the person can think that his "oral" agreement will act as a kind of insurance policy to ...