Why are words like "Thou" / "Thee" / "Ye" no longer used in English?

Solution 1:

English has been steadily losing many of its grammatical "complexities" (or beauty, depending on how much one enjoys grammar).

Thou and thee did not stress respect, to my knowledge. Whoever informed you as such probably felt that way due to associations between those particular pronouns and the King James Bible, which is probably where those pronouns are most associated with today.

Thou was the second-person nominative-cased pronoun. Simply put, it was the second-person form of "he" (subject). Its roots go very far back, but in Old English it was rendered þū.

Thee, on the other hand, was the second-person accusative-cased pronoun (analogous to our third-person "him"). In OE this was þē or þēc. Note that 'þ' is pronounced as a voiceless 'th', like the 'th' in thick.

You also has a similar storied past. It was simply the plural dative-cased second-person pronoun ēow (Old English had different pronouns for singular second person, when you're speaking to one person, versus plural second person, which we render as "you guys"). In modern English we form the dative case of nouns by putting it into a prepositional phrase like 'to you'. This was a single-word form of that.

English has lost many of its grammatical rules regarding case agreement. In concert with that, we've also lost having two sets of second person pronouns. For reasons mysterious, the language evolved this way. According to Google, in the 14th century 'you' began replacing 'ye', 'thee', and 'thou', and by the 17th century 'you' was the primary second-person pronoun for both accusative and nominative cases. Remember we still have the genitive your, which was also from the second-person plural genitive pronoun ēower.

References:

• Old English Grammar/Pronouns
• Etymology of you

Solution 2:

Thou/thee were originally forms of second person singular pronouns; You being the (polite) second person plural (not unlike the french Vous/ Tu dichotomy).

According to this article, they basically both just fell into disuse

Solution 3:

An interesting question. Albert C. Baugh in his A History of the English Language has in paragraph 182 a relatively short passage on the disappearance of the familiar personal pronouns thou, thee, thine, which are related with German du, dich, dein.

Baugh is relatively vague about the cause for the disappearance of thou. He hints at French influence. He only says that by the sixteenth century the familiar singular forms of the second person had all but disappeared from polite speech and are in ordinary use today only among Quakers.

Actually it is astonishing that such a radical change in the grammatical system can't be explained better.

Solution 4:

An explanation I've heard, but can't cite research on, is that the archaic letter þ thorn (th sound) as used in þe ("the", pronounced "thuh", pretend the e is a schwa) and þee ("thee", the "ee" is actually a long e, with macron) and þou ("thou", with an elevated "ou"). Over time þ lost its ascender and came to look very much like a "y", but still pronounced as "th".

When movable type was introduced to England from continental Europe, there was no þ or wynn. A "y" was the closest match in the type set, so it was substituted by printers, giving us "ye" (with schwa or long e, eventually the or thee as the vowels dropped to the baseline) and "you" (thou). Over time, ye as an article became the, thee as a pronoun pretty much disappeared, and thou became you (and the pronunciation shifted to the y sound).

Can anyone confirm or definitely refute this?