More “Or” Ambiguity

One of the chapters of MSCD that I sweated most over was chapter 10, “Ambiguity of the Part Versus the Whole.” Here’s the first paragraph:

Use of plural nouns and the words and, or, every, each, and any can result in ambiguity. In each case, the question is whether it is a single member of a group of two or more that’s being referred to, or the entire group, so this manual uses the phrase “the part versus the whole” to refer to this sort of ambiguity.

This topic is fiendishly complex, with the ambiguity varying depending on the grammatical context and the category of contract language that you’re dealing with. The literature on drafting has botched its treatment of this subject, and courts can be relied on to oversimplify it. When revising this chapter for the second edition, I bugged linguists and kept close at hand a copy of The Cambridge Grammar of the English Language. I’d like to think that the MSCD analysis is by far the most comprehensive and practical for purposes of understanding legal prose. (If I’m wrong, I’d like to know it!) But I’m looking forward to improving it for the third edition.

I feel a bit proprietorial about this topic, and I’ve revisited it sporadically in this blog, including in this May 2009 post about a Toronto restroom notice. I’m delighted to be able to revisit it again, thanks to this post by Neal Goldfarb on Language Log.

Neal’s post concerns a recent decision of the United States Tax Court regarding how cosmetic surgery is defined in the tax code. It’s defined as—

any procedure which is directed at improving the patient’s appearance and does not meaningfully promote the proper function of the body or prevent or treat illness or disease.

The question presented was whether in order to constitute cosmetic surgery a procedure has to neither meaningfully promote the proper function of the body nor prevent or treat illness or disease, or whether not doing just one of those two elements is sufficient.

I’ll leave you to read Neal’s post for the gory details, but here’s my take: if you don’t want to find yourself in court haggling about, in Neal’s words, “disjunction under negation,” you should familiarize yourself with the sources of “the part versus the whole” ambiguity and root it from your contracts. The kind of ambiguity at issue in the Tax Court case is discussed at MSCD 10.42–44.

Incidentally, Neal’s an interesting fellow, in that he’s a lawyer who’s knowledgeable about linguistics. By contrast, I’m entirely unschooled in the subject—my approach is to try to figure out what sounds right, then hit the books to determine the linguistics underpinnings of my instinct. I’m sure I would have benefitted from a more formal education in the subject, but a saving grace is that my approach ensures that my analysis is rooted in the needs of drafters.

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.

6 thoughts on “More “Or” Ambiguity”

  1. you could always rely on classical logic courses rule: De Morgan’s laws, for example. (

    Using De Morgan’s law, we’re told that “not (A or B) = (not A and not B).”

    For example, “I will not eat or drink = I will not eat and I will not drink.”

    Then you can just look at the truth table for the conjunctive table (! means not)(& means ‘and’):
    !T & !T = F
    !T & !F = F
    !F & !T = F
    !F & !F = T

    Thus, the only result of the clause that can be a “cosmetic surgery” is one that is not any of the choices.

  2. Ah, De Morgan’s law—reminds me of my computer science undergrad days.

    And also gives me a good idea. This blog has had a lot of posts about and/or issues (and the stupidity of using that expression). To solve this “problem” once and for all, I am introducing “xor” as a new word in the English language. Now we won’t have to deal with typing “A or B, but not both” or whatever is recommended. Instead, it will be “A xor B.” With this, all people will be able to agree that “A and/or B” is unnecessary as “A or B” would do it.

    Also, it would be a decent “x” word for scrabble.

    Also, ambiguous laws should always be interpreted in the favor of the taxpayer. (If not, would there be a due process violation?). Also, Congressmen introducing the bill (or adding the amendment) should be publicly flogged (or tarred and feathered).

  3. Ken —

    You might also want to point out to Mike that the original post by Mr. Goldfarb has an interesting discussion about the fact that “natural languages don’t necessarily follow the rules of formal logic. Indeed, the whole point of formal logic is to provide an artificial language that avoids the messiness of natural language.”

    It also contains an interesting discussion of why reference specifically to De Morgan’s law in a opinion concurring with the majority does not necessarily settle the question.

  4. Okay – trying to determine whether or not I have an ambiguity. Contract statement reads: "Upon the death of a Stockholder his interest shall pass to his OLDEST SON OR HIS OLDEST DAUGHTER (emphasis added) or in the event a stockholder has no oldest son or oldest daughter, then his estate shall sell, and the surviving stockholders shall purchase all of the shares of stock owned by the stockholder at the time of his death, for the price and upon the other terms provided herein, bearing in mind that the price of the shares for the first (15) fifteen years is $301.90 per share."

    Stockholder dies: There are three children: 1 daughter (55) 1 son (53) and another daughter (50). QUESTION: Since there is a superlative adjective "oldest" used for both the son and also for the daughter, would the statement presumably suggest the interest should go to the "oldest" child whether it be son or daughter? Who should receive the interest? Is this another case of "OR" ambiguity?


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