when is an assumption not a presumption?

I ASSUME THAT MOST OF US dare to presume when we should be merely assuming! Just the other day one of my friends drifted into discussing the difference between ‘assume’ and ‘presume’ and before either of us could look it up and find out the difference we were both called to other duties and there the conversation rested until now because I wanna know once and for all when is an assumption not a presumption! 1

First I used Merriam-Webster Online. Books with the MW trademark have been reasonably trustworthy since 1843, when George and Charles Merriam bought the rights to An American Dictionary of the English Language from the Noah Webster estate.

•  According to MW, assume means “to think that something is true or probably true without knowing that it is true.”

•  According to MW, presume means “to think that (something) is true without knowing that it is true.”



But! They both have the same definition!

(Why the one has one word in parentheses is probably known only to the hoariest of MW’s lexicographers.)



There is a second type of assumption, most closely identified with the Catholic Church: “The Assumption of the Blessed Virgin Mary into Heaven is a defined dogma of the Catholic Church. The Feast of the Assumption commemorates the death of Mary and her bodily assumption into Heaven—a foretaste of our own bodily resurrection at the end of tie.” I found this great engraving of The Most Famous Assumption in Western History on the website for The Cathedral of the Holy Family of Nazareth of Tulsa, Oklahoma. Alas, the artist is not credited.

A second opinion can turn an assumption into a presumption

So I turned to The Free Dictionary, an American online combined dictionary and encyclopedia that derives its explanations by cross-referencing the American Heritage Dictionary of the English Language, the Columbia Encyclopedia, the Computer Desktop Encyclopedia, the Hutchinson Encyclopedia, Wikipedia, and Acronym Finder, along with several specialist dictionaries (such as financial and legal).

•  According to the FD, assume means “to take for granted; suppose.”

 According to the FD, presume means, “to take for granted as being true in the absence of proof to the contrary.”

So, according to the two dictionaries that I refer to when online, there is essentially no difference between the definitions of the two words. But that is technically not so says the Grammarist:

Assume and presume both mean to take something for granted as true (among their many other definitions). The difference is in the degree of certainty. A presumption is usually more authoritative than an assumption. To presume is to make an informed guess based on reasonable evidence, while to assume is to make a guess based on little or no evidence.” 2



On November 10, 1871, American Henry Morton Stanley made The Most Famous Presumption in Western History when he greeted Scottish medical missionary David Livingstone with the question, “Dr. Livingstone, I presume?” Livingstone was a national hero in Britain, but hadn’t been heard from in six years at the time of this meeting. Stanley had been sent to find him by the New York Herald newspaper in 1869, and it took the intrepid investigative journalist two years before he located the man in the town of Ujiji on the shores of Lake Tanganyika. 3

The ass and u and me thing

This I like: a variation in theme, more or less. Most of the comments that followed the Grammarist’s explanation either concurred with that explanation, or expressed appreciation for having a line drawn between the two words. Several reasonable statements follow in the Comments section; my fave is from ‘Dash’:

“When you assume, you usually make an ass out of u and me. That’s exactly what happens when you don’t have enough information/evidence to make a presumption.”

I am content with this explanation, but for the sake of my more scrupulous readers, I pursued another explanation, this time from the Oxford Dictionaries on Language Matters:

“In common usage both assume and presume can mean ‘suppose’ and are often interchangeable in this meaning. However, technically there is a subtle difference between the two where presume is to suppose to be the case on the basis of probability. Assume on the other hand is to suppose to be the case without proof.”

I began this piece for my “Strunkandwhiten It” category assuming that I would reach some conclusion that satisfied my curiosity and that of most readers. I presume that I have:

•  All presumptions are assumptions; only the better breed of assumption is a presumption.

 You may assume any time you like and not look too foolish (as long as you have something factual to go by), but you’d better have more than an assumption to make a presumption.

 Good luck explaining the difference to those among us who think opinion is paramount.

Three quips to stick in you head

“There is nothing more deceptive than an obvious fact.” Sherlock Holmes said that.

“Your assumptions are your windows on the world. Scrub them off every once in a while, or the light won’t come in.” Isaac Asimov said that. 4

“Never make no f*cking assumptions!” I said that.



HEADER IMAGE: Wow! This may be the most mandala-like interpretation of the Assumption that I have ever seen! I found this on the website for the St. Francis de Sales Catholic Church of Norton Shores, Michigan, Diocese of Grand Rapids. It is used there to announce the holy day commemorating the Assumption of the Blessed Virgin Mary on August 15 of each year. Unfortunately, the artist is not credited. 5

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1   After all, never having to say you’re sorry is why Grommett, through his disciple Al Gore, gave us the Internet!

2   When forming a presumption, a little authoritative backing helps to differentiate it from a mere assumption, and the word authoritative has a meaning. Despite what our conservative brethren think, it does not mean “someone who shares my opinions.”

3   Isn’t “Dr. Livingstone, I presume?” a question (the first two words) within a statement? Stanley is stating to Livingstone that he is presuming that he is Livingstone, so the four words do not form a question, but a declaration. Shouldn’t it be properly punctuated as, “Dr. Livingstone? I presume.”

4   For more, Goodreads has another 157 statements on the foolishness of assuming much of anything. (Um, you won’t find my statement there.)

5   This image is so psychedelic that it makes me wanna unlapse (sic) my standing with the Church of Rome and see if this might happen to me!


5 Replies to “when is an assumption not a presumption?”

  1. Re. Footnotes 3 and 4: Assume nothing.

    Footnote 5: I thought it was an illustration from Dante’s “Inferno”!

    And, the whole thing goes round’n round. Paul Simon said it best, “The greatest story ever told.”

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