Why is “ss” equal to the German sharp-s character 'ß'?

Question

Coming from this question I\'m wondering why ä and ae are different(which makes sense) but ß and ss are treated as equal.

Answer 1

Most of what i read here is true. But there are some misconceptions involved, so – as a German – let me put this straight:

ß/ẞ is a genuin german letter comming from a ligature of either ſs or ſz but never ss. That is long-s followed by either s or z.

A mid-syllable s in german is pronounced /z/ while a start and end-syllable s is pronounced /s/. As the letter z in german is always pronounced /ts/, it needed a way to distiguish those rarer cases, where that rule is broken by adding another letter and finally forming that ligature for those cases, where a mid-syllable sound /s/ was needed.

The sound /s/ never occures in genuin german words in the beginning and just in one foreign word, where it is (tada!) written with sz: Szene. So the need for a capital ß (ẞ) first arrised as capitalization of whole words came into use. ß and ss are not the same, historically ſz and ß are, that's why it is called an "eszett"! There are certain rules that allow ß to ss translation if ß is not available which is not true in modern evironments.

The right capitalization of Maße is MAẞE, and the right capitalization of Masse is MASSE. Both are different words in german.

So, in actual german, ss is /s/ shorting the vowel before and ß is /s/ after a long vowel. Assuming ss and ß being equal in any comparation is simply wrong because it might force words of completely different meaning being equal. Period.