Why have a letter in a word when it’s silent in pronunciation, like the b in debt?
Can anyone please clarify my uncertainty here?
In general, never trust words in the English language to be phonetic! This is largely a consequence of English being such a fast-evolving language, and importantly, owing its vocabulary to many linguistic sources: Latin, Old French, Anglo-Saxon (a.k.a. Old English), Norse, and many others.
In this case it seems we have French to thank. This etymology is given online, and explains the supposed strange pronunciation:
In other words, debt comes via the Old French dete, which itself derives from classical Latin debitum. The b sound got lost due to French phonological rules/convention, and hence the French-origin pronunciation in English. Evidently, after the end of the Middle Ages in the 15th century, there was much revived interest in the classical world, and the spelling reverted to include the original b. Pronunciation, of course, stayed the same.
(Note that this sort of evolution occurred with many different English words, and occurred at the same time many new Latin words entered the English language.)
On the blessings of ‘silent’ letters in English
One important and often overlooked reason for having silent letters in the spelling of English words is because spelling in English is meant to do much more than tell you how to pronounce a word. For one thing, it can also tell you about the history of the word, its origins and its evolution. Not all languages have this property in their written forms, but English does.
It can also serve to create heterographs out of homophones, which helps when reading. For example, consider the word pronounced
As soon as you see it on the printed page, you know which of those four words it is. You don’t have to puzzle it out. This increases reading speed and proficiency.
Be Careful What You Wish For
The other largely unsung reason for how English spelling helps you is because if you actually spelled things the way people said them, no one could ever read anything anyone else ever wrote! Well, nobody outside their own current dialect — if that.
Even using something like
For example, when I think I am saying
It’s not an uncommon pronunciation, but there are many others:
As you can see from the list above, you do not have to spell English with “silent” letters. However, when you really do go to the trouble to spell it out phonetically, you thereby:
But because English has silent letters, none of that applies. This is a blessing, you know. You should be happy nearly to the point of being overjoyed that English has silent letters. They are a major win, and without them, we would all be lost.
I’m sure I remember reading that some “redundant” letters were inserted into English words by early printers, simply to make the typesetting easier or to improve the visual appearance of the text. The example given was the ‘h’ in “ghost”, though while Oxford does indeed attribute that to an early printer, it suggests that the influence was a foreign spelling rather than practicality or aesthetics.