Why is it common practice to say Nakdishach/Nekadesh before the hazzan?

Question

Shulchan Aruch OC 125:1 rules (and the Rama agrees):

אין הצבור אומרים עם שליח ציבור נקדישך אלא שותקין ומכונין למה ששליח ציבור אומר עד שמגיע לקדושה ואז עונים הציבור קדוש
The congregation does not say along with the leader "Nakdishach" but rather remain silent and focus on what the leader says, until he gets to Kedusha and then the congregation answers "Holy [Holy Holy etc.]"

In my experience, the majority of the shuls nowadays go directly against this and say Nakdishach/Nekadesh before the hazzan.

When did this custom come about and what was the reasoning behind it?

Answer 1

The Levushei Serad to OC 109 (bio) speculates that the custom is based on the Taz 125:1 who argues that even if there is no reason to encourage reciting along with the Chazzan it is not prohibited to do so. However, the Levushei Serad notes that this isn't satisfying as later authorities (eg. Peri Megadim) nearly universally question the Taz's proof. He remains uncertain (צ"ע) as to the basis of the custom.

R Akiva Eiger to OC 125 quotes the Nezirut Shimshon who quotes from the Ari who apparently thought that Kabbalisticly one should recite all of the parts of Kedusha along with the Chazzan. However, looking up the Ari inside shows from the continuation of the quote that he held that only the first two words נקדישך ונעריצך should be said aloud and the rest of the leaders parts should be said along quietly. It is possible though that people just stopped being particular about that at some point and thus was born the practice you see. In any event one would still probably have to accept the Taz from above (or some variation thereof) that there is no prohibition to justify going against the apparent Halacha for a Kabbalistic consideration.

Despite all that, the near universal traditional practice of all Rishonim - to not say it - was still recommended by many Achronim, prominent among them the Gra (Maaseh Rav 44).

Answer 2

The Shulchan Aruch HaRav says (O.C. 125:1):

אם כל הצבור נהגו לומר נקדישך עם הש"ץ אע"פ שאין אומרים בלחש מלה במלה עם הש"ץ אין למחות כיון שמקדישין בעשרה ואע"פ שאינו נקרא צבור אלא כשאחד אומר וט' שומעין ועונין אבל כשכל אחד אומר לעצמו כיחידים הם כמו שיתבאר בסי' תקצ"ד מכל מקום בדבר שבקדושה א"צ לכך שלא אמרו אלא אין אומרים דבר שבקדושה בפחות מעשרה אבל עשרה רשאים כולם לומר נקדש כמו שאומרים קדוש וברוך שהוא עיקר הקדושה ואעפ"כ אומרים כל הצבור אפילו שלא בדרך ענייה אחר הש"ץ כגון קדושת ובא לציון לדברי האומרים שאינה נאמרת אלא בי

Note that although it is similar to the Taz, it isn't the same argument. Rather based on the very Rosh that is the basis of the Beis Yosef and the Shulchan Aruch (see footnote 15 which (as indicated by the bold) was written by the author of the Shulchan Aruch HaRav or possibly his brother who collaborated on those footnotes), together with the observation that those that do require 10 to say those same pesukim in Uva LeTzion don't require the responsive format.

Note that this argument is completely independent of the Arizal's practice, as that is brought afterwards as a separate point.

Note that he considers this a justification for the practice, but does not pasken like it, he just says it should be tolerated.

Answer 3

The best theory is it is based on the opinion of the Arizal, as mentioned in the Biur Halacha from the Magen Avraham #2.

This theory works very well as we now have the source of a worldwide practice without a halachic basis.

The problem is that according to the way it is presented in the Magen Avraham, Nakdishakh Vinaaritzach and Kadosh Kadosh Kadosh is said out loud, and the rest is said quietly along with the chazzon, which seems to have gotten lost along the way, so now we have mixed minhagim.