Q: What’s the origin of the use of “afraid” in sentences like “I’m afraid I can’t help you” or “I’m afraid that is the case”? Is this apologetic sense considered old-fashioned today?
A: When the adjective “afraid” showed up in the 1300s (as affred or afreyd in Middle English), it meant alarmed or frightened.
But by the early 1600s, according to the Oxford English Dictionary, the expression “I am afraid” (or “I’m afraid”) was being used in the apologetic sense you’re asking about.
The OED says “I’m afraid” here means “I regret to say,” “I apologetically report,” “I suspect,” “I am inclined to think,” and so on.
Oxford’s earliest example is from Shakespeare’s The Taming of the Shrew (circa 1590): “I am affraid sir, doe what you can / Yours will not be entreated.”
In this citation from Jane Austen’s Pride and Prejudice (1813), Miss Bingley’s offer of help is rebuffed by Darcy:
“I am afraid you do not like your pen. Let me mend it for you. I mend pens remarkably well.”
“Thank you—but I always mend my own.”
(We’ve expanded on the OED citation to savor Miss Bingley’s comeuppance.)
The most recent Oxford example is from Bloodless Shadow, a 2003 detective novel by Victoria Blake: “I’m afraid I can’t discuss my cases.”
You ask if this apologetic sense of “I’m afraid” is now considered old-fashioned. Not as far as we can tell.
It seems as contemporary today as when Shakespeare put those words into the mouth of Petruchio’s friend Hortensio.