The courts resort to established rules of interpretation for assistance in solving the doubts found in ambiguous contracts. The cardinal rule of interpretation is that the court must endeavor to ascertain and give effect to the intention of the parties to the contract at the time of the making of the contract. Intention can not be proved by direct and positive evidence. It is a question of fact to be proved "like any other fact, by acts, conduct and circumstances". Thus the issue, the intention of the parties to the contract at the time of the making of the contract, is an issue of fact to be proved like any other fact. Relevant evidence is admissible—irrelevant evidence is not.
James B. Howe & John M. Davis,
Applicability to Assignees of Doctrine of Practical Construction of Contracts,
15 Wash. L. Rev. & St. B.J.
Available at: https://digitalcommons.law.uw.edu/wlr/vol15/iss4/3