Is there any opinion that permits davening Maariv before plag

Question

I davened at a shul this morning that announced mincha at 5:30pm with maariv following immediately after. Plag mincha is around 6:45pm today. I pointed this out to the gabbai and he said that there is an opinion that says that you can daven maariv before plag, and that it is ok in this case because otherwise the attendees would not daven maariv at all. I didn't argue with him, though based on what I have learned, you can't daven maariv before plag (and thus if you do, birkot keryiat shema would be ברכות לבטלות, not to mention that tefillat amidah is also לא בזמנו and is at best a תפילת רשות).

Does anyone know of a legitimate source permitting this practice (davening maariv before plag, specifically for those would would otherwise not daven maariv at all)?

Answer 1

As noted in a number of comments to the question, T'rumat HaDeshen in Responsum #1 struggles with the common (in his day) practice to pray arvit three or four hours before tzeit hakochavim (long before how he calculated p'lag hamincha).

His conclusion is that if one is in a place where the community cannot be persuaded to pray arvit later, one can more or less disregard the rules regarding the correct time for arvit and pray with them (relying on the bedtime shema to fulfill the mitzva of keriat shema).

Answer 2

There are 2 opinions of plag brought down in Shulchan Aruch Orach Chaim Siman 261 in the Beer Halacha:

להקדים וכו': הנה לפי מה שכתב המחבר לקמן בסי' תנ"ט ס"ב מוכח דס"ל די"ב שעות היום נחשב מעמוד השחר עד צאת הכוכבים ופלג המנחה הוא שעה ורביע קודם צאת הכוכבים א"כ אין בין דברי הרמ"א להקודם רק חלק עשרים מן השעה דארבעה מילין הם שעה וחומש לפי דעת המחבר שם ומפלג המנחה עד הלילה הוא שעה ורביע וידוע דרביע יתר הוא על חמישית רק בחלק עשרים.
According to the Rema Plag hamicha is 3 minutes before Shekia (sunset) which is a 20th of an hour.

The Be-er Halacha then brings the opinion of the Levush:

אח"כ מצאתי בלבוש בסי' רס"ז שהעיר בכ"ז ועי"ש שדעתו באמת **שפלג המנחה הוא שעה ורביע קודם השקיע
The Levush says Plag Hamincha is 1 hour 15 minutes before Shekia (suset).

Hungarians follow the Rema and litvaks follow the Levush.

So the questioner must have been a Hungarian askig a Litvuk how can plag Hamincha be 1 hour 15 miutes early which is almost exactly the difference between the Rema and the Levush of 1 hour 12 minutes. Add 3 minutes when the shaos zemanios (daylight hours split into 12) are slightly longer around April and August and you know why one Shul davens 1 hour 15 minutes before another. So no-one davened Maariv before their opinion of Plag!