R' Aryeh Kaplan - is there psak on hashkafa?
R' Aryeh Kaplan states clearly and unequivocally that the answer is no.
He discusses this issue in an article The Age of the Universe - A Torah True Perspective and he writes as follows
The second introduction is a principle (klal) that the Rambam makes in his Perush HaMishnayos. When one has a question of historical fact or hashkafah – there is no p’sak.
The Rambam makes this point in his Perush HaMishnayos on Shavuos, at the end of Makkos, and in a few other places in Shas.
In any case, the Rambam says clearly that in questions of hashkafah or history, there is no p’sak. In other words, if an opinion is found in Chazal or in our
accepted Torah seforim, one cannot say that we do not posken like that opinion. Thus, the Rambam often takes a daas yachid (the opinion of just one person) and builds an
entire hashkafah on it. He may use this opinion because it fits into his system of logic, even though it may be a minority opinion. He can do this, since the entire concept of p’sak only applies to questions of halachah and not to questions of hashkafah.
I am going to try to find these Rambam's in the Peirush Hamishnayos when I get home.
If R' Kaplan is right then it it completely and utterly negates the Slifkin ban.