Where do I begin?
PBA: You may have a point but we are not discussing Slifkin as an individual (at least, we shouldn’t be). We are discussing the Hashkafic movement that he epitomizes. Thus, defects in his formulation of the Hashkafa do not delegitimize what super-rationalism actually is. And my point was that Ikkarei Emunah are not the place for glib points to be made.
ROB: This statement, “that pretty conclusively shows that aggadata is not binding on us and we do not have to accept everything that chazal say in aggadata.” is Mach’chish Magideha and Kefirah. It’s not what Rabbi Ohsie (I read it after you mentioned it) said and not what the Rambam said. He just says that we cannot Pasken it, meaning that we cannot exclude one valid viewpoint (in Chazal) in favor of another. It does not mean that we can ignore Aggadic issues entirely, as you seem to want to do.
That being said, I will have to look through all of Rabbi Ohsie’s Mekoros because I think he might be mistaken anyway. While we cannot Pasken “Hashkafa” (according to the simple reading of the Rambam), the Rambam holds that Ikkarei Emunah fall under Halachah and not “Hashkafa” anyway.
It is certainly clear that we sometimes do reject Hashkafic viewpoints. The Gemara itself says that Rabbi Hillel’s Shittah is untenable. So we can call believing in Mashiach an Ikkar Emunah.
Whether we can do that with later opinions is an interesting issue. I don’t know how to answer that. I think it’s clear that we all believe that corporealism is absolute Kefirah, even though legitimate Rishonim said it. How we have come to reject those Rishonim, I can’t quite say. But it greatly troubles me when people write off Rishonim’s Shittos as Apikorsus and ignore them. We do it with the corporealist Rishonim, yes. But I don’t know how anyone today can claim the authority to do it in any other situation.