Why does English spelling use silent letters?
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:
debt
late 13c., dette, from O.Fr. dete, from L. debitum “thing owed”, neut. pp. of debere “to owe”, originally, “keep something away from someone”, from de- “away” (see de-) + habere “to have” (see habit). Restored spelling after c.1400.
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 /raɪt/. That can be any of:
- wright
- right
- write
- rite
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 /raɪt/ doesn’t work to tell you how to say the word if you do not already know English. That’s because that is a phonemic transcription, not a phonetic transcription. Speaking broadly, phonetics is what people actually say, whereas phonemics is more like what people actually hear.
For example, when I think I am saying /raɪt/, I am not. I actually pronounce all four of those words [ɹʷʌɪt] — or often enough, simply [ɹʷʌɪʔ]. You can also spell that [ɻʌɪʔ] if you prefer.
It’s not an uncommon pronunciation, but there are many others:
-
[ɾɜit]Hawick -
[ræ̠x̟tʰ]Buckie -
[rɐit]South Wales -
[rəit]Coldstream -
[ʁɛ̈it]Holy Island -
[ɹäˑɪt]North Carolina, Nigeria (Igbo), Rossendale -
[ɹäˑɪʔ]Morley -
[ɹäɛ̝̈tʰ]South Africa: Johannesburg -
[ɹa̠it]Longtown -
[ɹäi̞t]Middlesbrough -
[ɹäɪt]Alabama, Chicago -
[ɹäɪtʰ]Received Pronunciation -
[ɹäɪt]North Carolina -
[ɹä̝ɪt]Ohio -
[ɹaɪθ̠]Liverpool -
[ɹɐit]Antrim, Belfast, Boston, Chicago -
[ɹɐiʔ]Norwich -
[ɹɐɪt]Cornhill -
[ɹ̝ɐɪt]India: Delhi -
[ɹɐɪt]Singapore -
[ɹɑ̈ë̞t]Buxton -
[ɹɑ̟it̟̚]New York -
[ɹɑ̈ɪ̠t]Australia: Perth -
[ɹɑɪt]North Devon -
[ɹɑ̈ɪt]North Devon, New Zealand: Auckland -
[ɹɑɪt]Somerset -
[ɹɑɪʔ]London -
[ɹɑ̟ɪʔ]North Devon -
[ɹəɪʔ]Edinburgh -
[ɹə̟̝xt]Edinburgh -
[ɹɛ̈ɪs̺̆]Tyneside -
[ɹɛ̝̈xt]Antrim -
[ɹɜitʰ]Berwick -
[ɹɜ̟̆ıĭtʰ]Tyrone -
[ɹiˑtʰ]Tyneside -
[ɹʋ͡ɛ̈i̞ʰs̺̆]Tyneside -
[ɹʌ̞̈it]Edinburgh -
[ɹʌ̈itʰ]Standard Scottish -
[ɹʌ̈ɪt̚]Standard Canadian -
[ɻäiʰtʰ]Lewis -
[ɻäɪtʰ]Standard American
Summary
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:
- Cut yourself off from all your literature, so you can kiss your culture goodbye.
- Make it impossible to distinguish homophones.
- Disconnect a word’s history from its spelling.
- Force people to learn a much larger alphabet, one that requires several hundred letters — have fun typing those, too.
- Make it so that you can no longer communicate with anybody who lives two miles away, let alone two (or twelve!) thousand miles away.
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.