This is true for a lot of words and I don’t understand what the point of including letters if they’re not supposed to be pronounced.
In many cases, the words were pronounced as they were spelled many many many years ago. But over time, the way we say the words changed, but the way we spelled them did not. So you end up with words whose spelling no longer reflects their pronounciation.
In other cases, the words are borrowed from other languages with different rules for spelling.
Usually silent letters are left over from an era when those letters were pronounced. If you read Chaucer, every letter in “knighte” (which is how he spelled “knight”) is pronounced. Scribes kept that same spelling even after people stopped pronouncing all the letters. The same is true of plumb, numb, and dumb, where people stopped pronouncing the “b” but the spelling remained the same.
They were pronounced in the language the words come from. If you see silent letters in a word, look at the etymology of the word and it will probably make sense.
In the case of plumber is comes from the old French word plummier, which doesn’t have the b in it, but the French word plummier actually comes from the Latin word plumbarius. So, during the renaissance when they realized the Latin origin word had a b in it, they added it to the written language but it wasn’t ever pronounced with the b in French, and both the written form and spoken form were carried over to English giving us a silent b.
After 2 years of Latin I can tell you this answer. Some words have silent letters due to their origins and the evolution of language over time. In the case of “plumber,” the word comes from the Latin word “plumbum,” which means lead. Plumbing used to use lead piping. The “b” in “plumber” is a remnant of its Latin origin. Over time, the pronunciation of the word changed, but the spelling remained the same, resulting in a silent “b.” Spelling it as “Plummer” would not accurately reflect its historical roots.
derived from the Latin word ‘plumbum’, meaning lead (as in lead pipes). The word plumber gradually came to mean a person who installs pipes. It’s pronounced as it’s spelled. We’ve just decided over time that plummer was better than plum-ber