A Mystery of English Interpretation of “Endeavours” Provisions: Use of the Word “Probably”

I’m still in the weeds on efforts, so please indulge me. Consider the following (emphasis added):

  • In UBH (Mechanical Services) Ltd v. Standard Life Assurance Co. T.L.R., 13 Nov. 1986 (Q.B.)., the court said that “the phrase ‘all reasonable endeavours’ is probably a middle position somewhere between the other two, implying something more than reasonable endeavours but less than best endeavours.”
  • In Rhodia Int’l Holdings Ltd v. Huntsman Int’l LLC [2007] EWHC 292 (Comm), the court said, “An obligation to use reasonable endeavours to achieve the aim probably only requires a party to take one reasonable course, not all of them, whereas an obligation to use best endeavours probably requires a party to take all the reasonable courses he can.”
  • And this is from Kim Lewison, The Interpretation of Contracts § 16.07 (6th ed. 2017): “Although the content of such an obligation is a question of interpretation of the contract in question, it is probable that an obligation to use best endeavours is more onerous than an obligation to use reasonable endeavours.”

What do all these quotations share? Use of the word probably or probable.

I don’t understand it. To quote a useful English authority, Richard Calnan, Principles of Contractual Interpretation 13 (2d ed. 2017), “The purpose of contractual interpretation is to establish the intention of the parties to the contract. This is done objectively: what would a reasonable person understand their common intention to be from what they have written?”

You won’t find in Calnan’s book, or any other authority I’ve looked at, anything suggesting that contract interpretation is a function of the probability of a given meaning.

Can anyone explain this?

About the author

Ken Adams is the leading authority on how to say clearly whatever you want to say in a contract. He’s author of A Manual of Style for Contract Drafting, and he offers online and in-person training around the world. He’s also chief content officer of LegalSifter, Inc., a company that combines artificial intelligence and expertise to assist with review of contracts.