I have a fairly expansive Point of View [POV] regarding Elu v'Elu [E"vE].
From Rabbi Ben Hecht's writings, one can sense his disappointment when he senses intolerance or "delegitimization" of other opinions within the Halachic universe
I posted about allowing for tolerance with regard to [WRT] the Lower East Side [LES] Eruv. The sons and successors to R Moshe Feinstein [RMF] wanted to ban any attempt at an Eruv in Manhattan - which after all their late father had banned one many decades ago.
The argument FOR tolerating the LES is more subtle. It is after all not IMPOSING an Eruv. Rather it is merely enabling it for those who wish to - or need to - rely upon it. AISI - the Feinsteins are well within their rights to say:
"We oppose this Eruv and forbid our community to rely upon it"
But if they say:
"Anyone relying upon this Eruv has transgressed Shabbos" is over the line because it really implies
"Anyone relying upon this Eruv has UNCONDITIONALLY Transgressed Shabbos". Because IMHO no poseiq acquires exclusivity - absent a Sanhedrin.
There are many tricky areas to this E"vE concept. The first point I want to make is that it has been attacked by some non-Jewish systems.
Rabbinic Judaism does not always see things in black-and-white. While we might say that Hashem has a definitive read - we say "lo bashamayim hee" and humans have grayer perceptions.
Also Judaism is a bit more Eastern when it comes to paradoxes than are pure Westerners. We don't completely invalidate Western either-or thinking, nor are we slaves to it either. We allow for many paradoxes that Greek-style thinking will not condone, while more Eastern thinking has no problem with the same.
At this point, I have not discovered any definite parameters for E"vE; hopefully some of these boundaries will emerge as a result of the posts and feedback