“Likely” and “Probable”

The words likely and probable both express the degree of probability of something occurring.

They’re not vague words. Vagueness is a function of borderline cases—at what point does someone become tall? It follows that vague words such as promptly and material require that you assess circumstances from the perspective of a reasonable person. By contrast, likely and probable aren’t a function of reasonableness.

Nevertheless, likely and probable exhibit uncertainty of a sort that makes them problematic. In this post I said that likely might indicate a degree of probability greater than five on a scale of one to ten, or it might mean something different. The same could be said for probable.

Not convinced? Consider the following:
“Although the term ‘likely’ connotes something more than a mere possibility, it also connotes something less than a probability or reasonable certainty.” State v. Green, 18 Ohio App. 3d 69, 72, 480 N.E.2d 1128, 1132 (1984).
“Probable and likely are synonyms.” Anderson v. Bell, 303 S.W.2d 93, 98 (Mo. 1957).
Given that two courts came to different conclusions regarding how likely relates to probable, I don’t think you can rely on any court to have a clear idea what one or the other word means.

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.

12 thoughts on ““Likely” and “Probable””

  1. I don’t know if the Green court was being particularly meticulous with its usage.  “Less than a probability” is a nonsensical statement, mathematically.

  2. Agreed that a drafter cannot rely on courts to know what either “likely” or “probable” means. As “Guest” pointed out, in mathematics, every event has some degree of probability. 

    Both words are best avoided in contracts, because although they are everyday words, they partake of deep philosophy.* 

    The danger of using either word can be lessened by defining it in a verifiable way. 

    “The Vendor shall erect rainproof tents the day before Market Day at the Customer’s option. The Vendor shall bear the cost of erecting tents in any month when rain is likely, and the Customer shall bear the cost in any month when rain is not likely. Rain is ‘likely’ in November, December, January, February, and March, and not in the other months of the year.” 

    Obviously, the provision could be more concise, but the point is that you can cure the vagueness of “likely” and “probably” by defining them quantitatively or otherwise objectively.

    I disagree that they are not vague words, since whether one or more events pertinent to a contract are likely or probable could easily require that you assess circumstances from the perspective of a reasonable person.

    *What is the likelihood of a flipped coin coming up heads? Arguably, it’s never 50%, but always either 0% or 100%, only we don’t know which till after the flip. The Big Bang determined absolutely heads or tails, but we’re insufficiently familiar with the Big Bang to know which one till after the flip. This is the version of probability theory that considers itself a science of human ignorance rather than of something inherent in nature.   

      • 1 If you define “probable” or “likely” quantitatively, reasonableness may not come into it. (But it still could: see graph 4 below.)

        2 For example if a church contracted with a contractor to put on a Las Vegas night as a fundraiser and specified that none of the games of chance could have less than a 10% probability of winning, you’ve defined the problem away.

        3 But if the electrical linemen’s contract says they needn’t work on rainy days or days when rain is likely, it’s a poor drafting choice precisely because reasonableness comes into it, and reasonable people can differ over whether rain is likely.

        4 In such a case, even specifying an “X% probability” of rain would leave the reader in reasonableness land, unless the contract defines the percentage by an external standard like “according to Weather.com’s percentage rain probability for the Zip Code of the place of work.”

        In State v. Greene, cited in the lead article, a criminal statute contained the phrase “likely to be present” and the court stated:

        “A person is likely to be present when a consideration of all the circumstances would seem to justify a logical expectation that a person could be present.”  State v. Green, 18 Ohio App.3d 69, 72, 480 N.E.2d 1128 (10th Dist.1984).

        Without using the word, that passage reeks of a “reasonableness” standard.

        In the other case cited, Anderson v. Bell, the court held that “a jury could reasonably find” that the defendant “could have known that there was probable danger of collision between the two automobiles….”

        In both cases, reasonableness played a role in defining “likely” or “probable” where the terms were not more ascertainably defined. I avoid saying “objectively” defined, because the reasonable person standard is often said to be objective.

        It would ground the discussion better if EDGAR or some other source identified contexts where contracts actually use concepts like “probability,” “likelihood,” and “chance.” I confess I can’t think of any besides the church casino night hypothetical above. 

        I know Connecticut has an agreement (treaty?) with the sovereign Indian tribes that run casinos on their Connecticut reservations, but isn’t there anything more mainstream?

        • Determining whether you’ve exceeded the 50% likelihood threshold is just a matter of choosing the referee. That’s different from determining whether, for example, someone has acted promptly.

          But I think your comment gets at something I said in my original likely post: “Another problem is that referring to a mathematical degree of probability is fine when you’re rolling dice or playing cards, but it
          probably won’t be relevant for purposes of contract provisions featuring likely. So arguments over likelihood quickly become murky as you move from one or other end of the spectrum of probability into the middle. For example, I wouldn’t want to be involved in a debate over whether a given injury has a 49% or a 51% chance of rending Executive disabled.”

          In other words, when you’re not at one or other end of the spectrum, you’re winging it. That’s not a function of reasonableness but instead a function of working without meaningful guidelines.

  3. Ken, I agree that these words should not be used in contracts, because there is no universal meaning.  If you take the approach suggested in the extract from State v Green, you might end up with a range of words indicating a scale of mathematical probabilities. With no scientific or linguistic justification, how about this scale (rounded to the nearest whole number percentage) of percentage probabilities:

    Impossible: 0%
    Barely conceivable / very unlikely: 1-10%
    Possible: [1][11]%-100%
    Plausible: [11][26]% – 100%
    Unlikely: 0% – [50]%
    Likely [more likely than not]: [51]% – 100%
    Probable: [51][76]% – 100%
    Beyond reasonable doubt / sure: [91]% – 100%
    Certain: 100%

    English case law indicates that for civil cases the standard of proof is “the balance of probabilities” or “more likely than not”, ie 51%-100%.  For criminal cases is it “beyond reasonable doubt” or “sure”.  Although I am not a criminal lawyer, I have associated this standard with 90% probability (but I am not sure where I got this from).

    In some of the examples you quote in your earlier article, the phrase used is “reasonably likely”.  This is even more woolly than likely, and might mean more or less than 50% probability.

    I recall some negotiations several years ago where the parties got hung up over the words “substantial”.  We found English case law on “substantial [rent increases]” where the percentages hovered around 15%, while the other party, from Canada, were looking at Canadian cases indicating a much higher percentage (more than 50% but I can’t remember the figures) in cases involving a completely different set of facts.

    Much better to avoid these words…

  4. I think that the discussion over what percentage probabilities certain words correspond to is a red herring. As no one can calculate a percentage likelihood of most events occurring, because most events are unique and dependent on very uncertain variables, any percentage probability is an estimate based on intuition, dressed up as a precise number. It is not any more scientific, accurate or mathematical than using words like “probable” or “likely”.

    Percentages may have some advantage in terms of ambiguity, though it is probably harder to reasonably assess whether something has a 0%-25% chance of happening than assessing whether it is “unlikely”, because of the way our brains work.

  5. I think likely indicates what one can assume independently, for a probability one also has to consider external factors – read other people, situations etc.

  6. The two cases were a generation apart, however, and although they may set confusing precedents, they may reflect the way languages changes.

    I grew up in the 1980s, and my impression of the meaning of the two words matches the 1984 case. I also note that the 1957 case was released before this CIA article was made public, so perhaps it influenced the general understanding of the two terms in the intervening quarter-century: https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/sherman-kent-and-the-board-of-national-estimates-collected-essays/6words.html

    (‘Perhaps’, to me, means the odds are in the range from zero/impossible to likely. 😉)


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