Q: I was taught that “persuade” is used with “to” and “convince” with “of” or “that.” This rule must have changed when I wasn’t looking, since I can’t for the life of me figure out how the two verbs are being used now. Your help would be appreciated.
A: Yes, “convince” and “persuade” once had two different meanings.
The old rule was that you “convince” someone “of” something or “that” something is the case, while you “persuade” someone “to” do something.
In other words, “convince” meant to make someone believe something, while “persuade” meant to make someone believe something and act on that belief.
However, most standard dictionaries have dropped the old distinction. Today both verbs can be used with “to” infinitives, “of” prepositional phrases, and “that” clauses.
The American Heritage Dictionary of the English Language (5th ed.), for example, has almost identical definitions of “convince” and “persuade”:
Convince: “To cause (someone) by the use of argument or evidence to believe something or to take a course of action.”
Persuade: “To cause (someone) to accept a point of view or to undertake a course of action by means of argument, reasoning, or entreaty.”
So now you can say: “The polls convinced [or “persuaded”] the candidate to drop out” … “He was convinced [or “persuaded”] of the need to drop out” … “The polls convinced [or “persuaded”] him that he should drop out.”
In fact, “persuade” has been used in all three ways since it showed up in English in the 15th century, according to the Oxford English Dictionary.
And “convince” has been used similarly since the 17th century, according to our searches of literary databases, though its use with an infinitive wasn’t common until the 20th century.
Merriam-Webster’s Dictionary of English Usage notes that the expansive use of “persuade” is long established, while the similar use of “convince” is now “fully established.”
Merriam-Webster’s adds that language commentators insisted unsuccessfully for a century and a half that “convince” and “persuade” had distinct meanings.
“The earlier usage writers who tried to fence off persuade from convince and the later ones who tried to fence off convince from persuade have failed alike,” the usage guide says.
Even the conservative Garner’s Modern English Usage (4th ed.) acknowledges that the use of “convince as an equivalent of persuade” is “fully accepted” (that is, stage 5 on Garner’s index of language change).
The oldest of the two verbs, “persuade,” is ultimately derived from persuādēre, classical Latin for to get someone to believe something or do something.
When the verb showed up in English in the mid-15th century, according to the Oxford English Dictionary, it meant to “induce to believe or accept a statement, doctrine, etc.; to convince that or of; to urge successfully to think, believe, etc.”
The earliest OED citation is from an English translation, dated around 1450, of Giovanni Boccaccio’s De Claris Mulieribus (Concerning Famous Women):
“This witty lady togyder didd them call … Persuadynge them …To thynke that they were creatures racionall And vndirstondyng hadd of good and ill.” (The Latin work is a collection of biographies of historical and mythological women.)
The dictionary’s first citation for “persuade” meaning to make someone believe and act on the belief is from a translation, dated around 1487, of Bibliotheca Historica, a 40-book world history written in the first century BC by the Greek scholar Diodorus Siculus:
“They perswade the kyng wilfully to take his deth aftre the accustumable vsaige observed of olde” (originally translated by John Skelton; edited by F. M. Salter and H. L. R. Edwards, 1968-1971).
As mentioned above, we’ve found examples from the 17th century for “convince” meaning to make someone believe something and act on that belief.
Here’s a passage from a statement by Sir Francis Winnington during an Oct. 30, 1680, debate in the House of Commons:
“I conceive, by the proposal of this Question, that the House is fully convinced to proceed to prepare things to bring these persons to Judgment” (from Debates of the House of Commons from 1667 to 1694, published in 1763).
Finally, here’s a 20th-century example from The Powers That Be, a 1979 book by David Halberstam about the American news media: “He worked very hard personally to convince Ike to run.” (The reference is to Henry R. Luce, creator of the Time-Life magazine empire.)