Which of the following is NOT a principle needed to form a valid contract?

To form a valid contract, several key principles are essential, two of which are offer and acceptance, as well as consideration. An offer is a clear proposal made by one party to another, which is then accepted by the other party, indicating mutual agreement. Consideration refers to something of value that is exchanged between the parties involved, which is necessary for the contract to be legally binding.

Negotiation, on the other hand, while important in the process of reaching an agreement and discussing terms, is not a formal requirement for a valid contract. Contracts can be formed without extensive negotiation, as long as there is a clear offer, acceptance of that offer, and consideration in place. Therefore, negotiation does not serve as a foundational principle in the same way the other elements do when legally establishing a contract.