Why does English have so many silent letters

For people around the world, English is now becoming one of the most common and accessible languages. No matter in which part of the world you go, and if you know the native language or not, English can bridge the gap to some extent and help you go around.
But even today, for some, English is one of the trickiest languages to learn, and one of the reasons is the abundance of silent letters in it. The way people pronounce ‘schedule’ as ‘scedule’ or the way ‘debt’ becomes ‘det’, but ‘debit’ remains the same, is the tricky part for many.
And this gap in writing and pronunciation is owed to the ‘silent letters’.

Silent letters are basically alphabets in a word that are not pronounced when spoken. For example, in the word knight, the ‘k’ and ‘gh’ are silent, and what we pronounce is ‘nite’. And when we say ‘castle’, the ‘t’ is silent, owing to ‘casle’.
And overtime, silent letters became much more prominent in English, and are pretty much everywhere in the word. The letter could be silent in the beginning, middle, or end of words.

If you ask a non-native speaker if silent letters help them, the answer would probably be no. For many, it just complicates their understanding. And while they do make spelling a word difficult, they have a very important purpose - distinguishing words.
For speakers, silent letters help differentiate words that would otherwise be homophones, i.e., words that sound the same but have different meanings. For example ‘knight’ is a warrior, and ‘night’ is the opposite of day, but they both have the same pronunciation, and the spelling difference would make it difficult to decipher which is which.

Well, there are many reasons for English having silent letters. And according to reports, the most common one is that English words are often borrowed.
English has borrowed words from different languages, including Latin, Greek, French, and German, and many of these borrowed words retained their original spellings, even when pronunciation changed over time.
For example, English inherited silent letters from words like ‘Debitum’ from Latin, ‘honnete’ from French, and the likes.
The Great vowel shift
Another reason people say that English has so many silent letters is because of the Great Vowel Shift between the 15th and 18th centuries. During this time, vowel sounds changed dramatically, but spellings remained the same. For example, some say that ‘her’ was pronounced as ‘here’ before, but now it is just ‘har’.
Changes in pronunciation
Another reason English has so many silent letters is that the way people pronounce words changes over time, and speech does not just become simpler, it also changes for the worse sometimes, making a word difficult to pronounce and understand.
As a result, silent letters remain in words even though they are no longer pronounced. For example, the "gh" letters in ‘though’ are now silent and it is simply pronounced ‘tho’. Plus, the ‘t’ from soften has become silent, and people often just say ‘soffen’.

Silent letters appear in many commonly used words. For example, the ‘K’ is missing from the pronunciation of words like knife, knee, knock, knowledge, and more. Similarly, the letter ‘G’ is silent from sign, gnome, foreign, etc.
Overtime, even the pronunciation of ‘B’ letters has become silent in words like subtle, thumb, comb, and the likes.
And of course, there is the more common silence of ‘H’ from words like honest, schedule, hour, ghost, rhino, and more.
And replacing the ‘W’ with the sound ‘R’ are words like write, wrong, answer, etc.

For non-native speakers, silent words can be difficult to learn and understand, and even remember. For a non-native speaker, the most common question would be ‘why is the ‘H’ in ‘Honest’ silent even though it is the first letter itself?’
But as English speaking and practice increases and improves, people start getting a hang of silent letters.
Memorising words with common silent ‘H’ sounds or ‘N’ sounds can help overtime. Then reading and writing words with silent letters repeatedly helps to etch the silent letters in your knowledge. And the best of all is to listen to native speakers, preferably ones with simple accents so as to not complicate understanding.