
Some languages choose to capitalize multiple pronouns, while others don't capitalize any. English, however, is unique in that it only capitalizes the first person singular, I.
But why is this the case? Truthfully, linguists and historians are uncertain. No definitive explanation has ever been found. What we do know is that in Old and early Middle English, the German-derived ich was the personal pronoun. Over time, during the Middle English period, pronouns evolved and variations like Ich, ich, Ic, ic, I, and i were all used in written form. By the end of the Middle English period, I emerged as the sole survivor, standing tall. The ch sound was dropped in one of the major phonetic shifts that English underwent, but the reason why the lone i was suddenly capitalized remains unclear.
Various scholars have put forward different theories to explain this phenomenon.
One theory is that capitalization was a linguistic choice. When I appears in sentences, it is often the subject, and capitalizing it may have been a way to highlight its significance in a statement.
A related idea is that capitalization serves a psychological purpose, emphasizing not the subject, but the writer themselves. However, if the intention was ego-driven, why wouldn't me also be capitalized in every instance?
Another suggestion is that the capital I had more to do with the practicalities of writing than with language. The lowercase i appears a bit flimsy on its own. Some historians, including Charles Bigelow, a type historian and the designer behind the Lucida and Wingdings fonts, argue that a lone i could become illegible after being handled and read multiple times, and scribes had to make the pronoun more visually solid to withstand the wear and tear of time and smudged hands.
