I do not think we should allow one party to defeat a contract for their genuine mistake even though the other party is not mistaken and is not at fault. I think this because if unilateral mistakes were allowed to be a defense to contract formation, then there would be a lot more mistakes made in contracts. This would be because people would start to become less careful when reviewing or creating a contract, because they ultimately know that if they make a mistake then they can just void the contract altogether and start over. With unilateral mistakes not being a defense to contract formation, this helps people know to thoroughly review the contract for any mistakes before the contract becomes binding. Thankfully there are a couple of exceptions to unilateral mistakes, like when the other party knows or should have known about a mistake of fact. Another exception is substantial mathematics error. I think both those exceptions are a good ground for unilateral mistakes.