Why English is like this

A history of borrowing.

Layers of language

English took words from Old English, Norse, Norman French, Latin and Greek, keeping much of the original spelling while pronunciation drifted. The result is several systems overlapping.

Silent letters often mark a word origin: knight, psychology, debt.
Printing fixed spellings before pronunciation had settled.

What follows

Rules hold within a family of words rather than universally. Knowing where a word came from often explains a spelling that looks arbitrary.