Q: I’m stumped by the use of “due” in this sentence by Bertrand Russell about Plato’s cave allegory: “Inevitably they regard these shadows as real, and have no notion of the objects to which they are due.”
A: In the cave allegory, as you know, a group of people have lived chained to the wall of a cave since childhood, and shadows cast on the wall by a fire behind them become the prisoners’ reality.
In History of Western Civilization (1946), Bertrand Russell discusses the allegory, a Socratic dialogue in Plato’s Republic, written in the fourth-century BC. Here’s an expanded excerpt that puts Russell’s sentence into context:
“Between them and the wall there is nothing; all that they see are shadows of themselves, and of objects behind them, cast on the wall by the light of the fire. Inevitably they regard these shadows as real, and have no notion of the objects to which they are due.”
In that last sentence, “the objects to which they are due” means “the objects to which they are attributable” or “the objects that they are due to” or simply “the objects that caused them.”
We wonder if Russell’s awkward wording may have been due to his unwillingness to end the sentence with “due to.” However, the so-called rule against ending a sentence with a preposition is a common misconception that we’ve written about on our language myths page.
As for “due to,” the usage showed up in the 17th century as an adjectival phrase meaning “caused by” or “resulting from.” But over the last century and a half, it has also been used adverbially as a compound preposition meaning “because of” or “on account of.”
The newer usage is now accepted by all 10 online standard dictionaries that we regularly consult. Lexico, the former Oxford Dictionaries Online, cites this example of “due to” used to modify a verb: “he had to withdraw due to a knee injury.”
Despite the acceptance by dictionaries, some traditionalists still object to the usage. The critics insist that “due to” should introduce an adjectival phrase that modifies a particular noun.
When “due to” first showed up in writing, according to citations in the Oxford English Dictionary, it was used adjectivally in the predicate to mean “attributable to a particular cause or origin; derived or arising from; caused by, consequent on; as a result of.”
The OED’s earliest example is from a scientific treatise: “The motion of the Oyly drops may be in part due to some partial solution made of them by the vivous spirit” (The History of Fluidity and Firmnesse, 1669, by Robert Boyle).
However, the OED says the usage was rare before the 19th century, when it widened to include the use of “due to” as a compound preposition meaning “as a result of, on account of, because of.”
The dictionary’s first example for “due to” used adverbially as a compound preposition is from another scientific treatise: “electric currents produced by periodical variations of temperature at its [the earth’s] surface, due to the sun’s position above the horizon” (1840, Royal Society report on a British expedition to Antarctica; we’ve expanded the citation to include the verb).
“This use became well established during the 19th century, and is now usually regarded as acceptable standard English, but began to be criticized in usage guides in the early 20th century, apparently beginning with H. W. Fowler,” the OED says.
In the 1926 first edition of his Dictionary of Modern English Usage, Fowler says “due to is often used by the illiterate” as “a mere compound preposition.” But in the 2015 fourth edition, Jeremy Butterfield says “it looks as if this use of due to is now part of the natural language of the 21c.”