Final answer:
A situation where only one party is mistaken about a basic contractual assumption is called a unilateral mistake. This occurs amidst imperfect information and can impact the enforceability of the contract if the mistake substantially alters the agreement basis.
Step-by-step explanation:
When only one party, and not both, misunderstands the facts relating to a basic assumption on which a contract is made, this situation is termed unilateral mistake. In the context of contract law, a unilateral mistake occurs when one party is mistaken about a material fact pertinent to the contract's terms, while the other party is not misled. It is essential to understand that imperfect information can lead to such mistakes, and when arguing for a particular interpretation of a contract, rhetorical strategies and understanding the language used in the contract are significant.
In the case of a unilateral mistake, it may affect the contract's enforceability if it was so fundamental that it substantially altered the agreement's basis. Recognizing and addressing asymmetric information is crucial in preventing disputes arising from unilateral misunderstandings. Often, reliance on imperfect knowledge can cause one party to conclude erroneously about the terms or implications of the contract.