I feel the phrase "more likely than not" is often seen or heard here and there, sometimes in a sentence, other times just the phrase alone like the following ones.
"More likely than not" a COVID-19 vaccine is possible, Fauci tells Senate
https://arstechnica.com/tech-policy/2020/05/fauci-adequate-response-needed-to-reduce-deaths-from-covid-19-rebound/
More Likely Than Not? This is Scientific?
https://www.econlib.org/archives/2013/12/more_likely_tha.html
I am now curious about:
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How likely is it for you in percentage terms? (My perception is somewhere between 51% and 55%)
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Is there any phrase describing exactly the opposite, which implies a probability level of around 46% to 49%, for example? Any such phrase especially in a similar word combination like "less likely than xxxxx", if any?
Best Answer
"More likely than not" logically means with a probability greater than 50%. A probability of 50% would be "as likely as not".
But the user of the phrase is not making a mathematically precise estimate of probability. They are expressing what they think is likely in an intentionally vague way, and it's misplaced precision to try to assign a number to it.
As an opposite, one could simply say "unlikely" to mean a probability of less than 50%. Or, given a proposition A, one could say "It's more likely than not that A is false."
I guess you could say "less likely than not", but I've never heard that.