Quote from: augustocroppo on November 09, 2012, 03:48:36 AM

Now you are pretending that a signed contract cannot determine if the mutual agreement was changed or not. In case you do not know, contracts are signed to avoid any party to append additional obligations that were not part of the mutual agreement. If you were wise enough to read the book I recommended to you, instead to spell out your arrogance, you would find this:

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A written offer containing all the terms of the contract, signed by the proposer, and accepted by the other party by performance on his part, is enough to enable the latter to sue under the statute of frauds. And where there is no such necessity for writing, it is optional with the parties to express their agreement by word of mouth, by action, or by writing, or partly by one and partly by another of these processes. It is always possible, therefore, that a simple contract may have to be sought for in the words and acts, as well as in the writing, of the contracting parties. But in so far as they have reduced their meaning to writing they cannot adduce evidence in contradiction or alteration of it. They put on paper what is to bind them, and so make the written document conclusive evidence against them.

This is called the parol evidence rule. It is important to remember three things:

1) The parol evidence rule only applies to things that occurred *before* the contract was reduced to writing. The logic is that if the parties intended their previous agreements or terms to be part of the final agreement, they would have included them in that final agreement. This can't apply to subsequent acts. (Though if the contract specifically states how the contract may be modified, this is usually enforceable.)

2) The parol evidence rule does not apply to evidence of fraud, mistake, or other ways to invalidate the contract. These are not forms of extrinsic evidence seeking to modify terms of the contract, and so are not restricted by this rule.

3) The parol evidence rule only applies if the written agreement appears to have been intended by the parties to encompass their complete agreement. This is why many contracts specifically state that they are the entire agreement.