In the ongoing conflict between Open Orthodoxy and the rest of the Torah observant community, one word keeps popping up on the non-OO side of the debate: mesorah.
It's a loaded word, mesorah. It means tradition and transmission all rolled into one but, like many other Jewish terms that have been hijacked by a group within our nation it's current use is a new one not reall envisioned by its creators. (Think tikun olam and how the Reformatives changed it)
Mesorah is, like Daas Torah, a magical concept owned by the Agudah and those to the right of it. It's a magical word which means "they way we present Torah Judaism today is the way its always been since Har Sinai and anything that deviates from our standard is a lesser version."
Why do we listen to our "Gedolim" even when they talk about subjects they have no expertise in? Mesorah! Why do we dress so rigidly? Mesorah! Why do we relegate women to second class status and erase their existence from public life? Mesorah! Why do we oppose women rabbis? Mesorah!
The problem is that arguing against that position when it comes to some of Open Orthodoxy's egalitarian innovations really paints one into a corner. The easy response to "Women rabbis are forbidden because of mesorah" is two words: Turkey and kitniyos.
Turkey is a response because technically speaking it shouldn't be kosher. The Torah contains two lists of birds that are not kosher and the Gemara in Chullin derives from this that since the Torah always mentions the short list of two options it must mean that all other birds in the world are kosher. It then goes on to fully describe the signs differentiating a kosher bird from a non-kosher one but concludes that since we are not expert in examining birds for these simanim we avoid eating any bird that we do not have a valid mesorah for its kashrus.
The problem with turkey is that, on one hand, it has the simanim of a kosher bird. On the other hand the Chazal, Rishonim and early Acharonim never heard of it because it existed only in the Americas so there was no way to include it in the mesorah of kosher birds. Despite this the vast majority of Jews have been eating turkey, probably because it looks like a giant chicken, since it was discovered. This led to lots of teshuvos with the final decision being that turkey is kosher.
Why is this relevant? Because one of the main reasons used to justify turkey's kashrus is that it got itself into the mesorah in a back handed way. That is, most Jews ate it because it lacked the simanim necessary to forbid it outright and now that most Jews eat it, it has a mesorah of being kosher and until someone can provide proof of a non-kosher siman, it remains acceptable.
And that's something the OO's can use to their advantage. Sure women rabbis aren't acceptable under the current mesorah but here's a great example as to how the mesorah changes based on popular behaviour. The more women rabbis become accepted by the population of Torah observant Jews, the more the mesorah will grow to include them until eventually the mesorah will demand proof from the person who wants to disqualify them.
Then there's kitniyos. Everyone Ashkenazi knows this one. While our Sephardi brothers are enjoying a delightfully spiced rice and pea pillaf at the seder we Ashkenazi are chewing on our waterproof non-gebrokht matzah balls. (Did you know that matzahs are male? Well apparently so) Originally designed to forbid to Ashkenazim those foods that might accidentally come to resemble chometz foods, the numbers slowly grew from the original list as more and more foods came to be of concern. But one food should concern us. Peanuts is on the list. What's the problem with that? Well, like turkeys peanuts started off in the Americas. The Rishonim who created the concept of kitniyos didn't know of their existence. What's more, exactly who uses peanut flour for anything? Yet there they are on the list, probably because they're a legume and other legumes are kitniyos but strictly speaking there's no way there's any mesorah about peanuts, just like there isn't with turkeys.
This leaves proponents of the mesorah with a difficult choice: either ban turkeys and allow peanuts on Pesach or admit that the mesorah does change over time and be left without a good argument against women rabbonim.
Which is a shame because there's plenty of other good reasons to maintain the status quo, just they require a lot more thinking and explaining.