Q: I know what the phrase “have to” means, but it doesn’t make sense if you take the individual words literally. For example, “I have to wash the dishes.” It would make more sense to say “need to” or “must.” Is “have to” a vestige of Old English?
A: You’re right in suggesting that the usage has its roots in Anglo-Saxon times. In early Old English, people who intended or needed to do something would say they had something to do—a forerunner of the usage you’re asking about.
As the Oxford English Dictionary explains, “the duty or thing to be done was initially expressed as a direct object of the verb (to have something to do), then in an infinitive clause (to have to do something).”
The earliest example of the usage in the OED is from an early Old English translation of Historiarum Adversum Paganos, a comparison of pagan and Christian times, by the theologian and historian Paulus Orosius:
“Nu ic longe spell hæbbe to secgenne” (literally, “Now I long story have to say” or, more naturally, “Now I have a long story to tell you”).
The OED says this early use of “have to” expressed “something that is to be done or needs to be done, as a duty, obligation, requirement, etc.”
That usage developed into the modern sense of “have to” as an auxiliary phrasal verb expressing necessity or, as Oxford puts it, “to be under an obligation to do something; to be required to; to need to.”
“Because word order was unfixed in early periods, it is difficult to determine precisely when this sense arose,” the OED says, adding that some Old English citations “are syntactically ambiguous, and may be transitional.”
However, the dictionary notes, “It has also been suggested that in early use the construction may occasionally approach a periphrastic or modal future” — that is, “have to” may have been used in Old English much like a phrasal verb in its modern sense.
(Modal auxiliaries, like “can,” “could,” “will,” “would,” and “must” express necessity or possibility. A periphrastic construction uses a combination of word, like “have to” or “need to,” in place of one.)
The OED gives an Old English example from the West Saxon Gospels that may show “have to” used in its modern sense of “must.”
The citation is from a translation of the Latin text of Matthew 20:22, where Jesus asks Zebedee’s sons if they are able to drink the cup of suffering that he will drink (bibiturus sum):
“Mage gyt drincan þone calic ðe ic to drincenne hæbbe” (literally, “Can you drink the cup that I to drink have?” or, more felicitously, “Can you drink the cup that I have to drink?”).
Does “to drincenne hæbbe” here mean “will drink” (a literal translation of the Latin) or does it mean “must drink,” a theological interpretation of the Latin passage by Anglo-Saxon scholars?
We lean toward interpreting “to drincenne hæbbe” as “must drink,” since other Old English translations of the same passage are closer to the Latin, according to Andrzej M. Łęcki, a linguist at the Pedagogical University of Cracow in Poland.
In Grammaticalisation Paths of Have in English (2010), Łęcki cites Old English translations of bibiturus sum in Matthew as “I will drink” and “I am drinking.” The Rushworth Gospels, for example, translates it as “ic drincande beom” (“I am drinking”).
Enough Old English. We’ll end with a very contemporary “have to” example in the OED from the July 22, 2012, issue of the New York Times: “You will have to enter the user name and password that corresponds to your account.”
from Grammarphobia http://www.grammarphobia.com/blog/2016/07/have-to.html