Assume vs. Presume: How to Choose the Right Word

The words "assume" and "presume" are both verbs which come from the Latin verb sumere, which means "to take." In common use, the two words are often used as synonyms meaning "suppose." Yet "assume" and "presume" are not exact synonyms, and they are used in different contexts. "Assume" refers to the act of laying claim to something or a statement that is taken for granted. "Presume" refers to a belief that something is true even though it hasn't been proven, an attitude or belief that's been determined by probability, or the overstepping of proper bounds.

How to Use "Assume"

"Assume" is a verb with two separate but related meanings. First, "assume" means to suppose that something is true, despite having no proof, or to take something for granted, as in "I 'assume' you will cook dinner this evening". This is by far the most common use of the word.

A second, less-common meaning is to take on, shoulder, or accept responsibility or an honor of some sort, as in "She 'assumed' leadership and led the group to success." "Assumption," the noun form of "assume," carries the same meanings, as in "His 'assumption'' was incorrect," or "Her 'assumption' of power was difficult to accept."

"Assume" also has several other less-common meanings: (1) to take control, (2) to pretend, or (3) to don or put on an article of clothing. All of these are more literary uses, but they do appear in both historical and contemporary literature.

How to Use "Presume"

"Presume" is listed in some dictionaries as a synonym of "assume," and, as such, is often substituted for "assume." "Presume," however, has a subtly different meaning. Unlike an "assumption," which may have no particular reason behind it, a "presumption" is based on some level of proof, as in "I 'presumed,' based on our past experience, that the dinner would be excellent."

"Presume" also has a very different meaning: It is synonymous with the word "dare" and means to take an action that is offensive and, usually, not allowed, as in "You should never 'presume' to address the queen by her first name!" This use of the word can also be described as taking a "presumptuous" action.

Examples

"Assume" and "presume" often are used interchangeably. For example, both of these sentences are correct:

• I assume I can get my money back if I can't attend the event.
• I presume I can get my money back if I can't attend the event.

The following are uses of "assume" that are not synonymous with "presume":

• Marianne assumed the position of CEO of Big Corporation, Inc.
• Eileen assumed that she would inherit all her parents' belongings.
• Mrs. Jones assumed her favorite outfit: a black dress and mink stole.
• Anthony assumed the appearance of a monk, making it harder for the police to track him.

These uses of "presume" are not synonymous with "assume"; in the first sentence, the context shows that Jacob had a good reason for his presumption, and in the second, the word is used as a synonym for "dare":

• Jacob presumes that he will become president of the company, based on his series of quick promotions.
• Because of his position as the church warden, Roger presumed to castigate the priest for his boring homily.

How to Remember the Difference

It's important to recall that, in some cases, the two words are really synonymous. When they are not synonymous, it's helpful to remember that assumptions are not based on proof, whereas presumptions are based on proof.

Unusual uses of the words can be remembered in this way:

• When "presume" is used to mean "dare," try substituting the word "dare" for "presume." If the meaning of the sentence is the same, use the word "presume."
• When someone is taking or putting on something, the word "assume" is correct.
• When someone is overstepping his or her bounds, the word "presume" is correct.

Sources

• "'Assume' or 'Presume'?" Oxford Dictionaries | English, Oxford Dictionaries.
• "Presume vs. Assume." Grammarly Blog, 7 Apr. 2017.