There was also an approach developed by Saadia Geon that when the literal meaning is impossible (according to Reason) then we must understand it as an allegory.
The Maimonides approach was of a first level of Natural Law, and then a higher level of Law that can only be known by revelation.
Reform Judaism I think was too much influenced by the Reformation in which the laws of the Torah were considered superfluous. Or perhaps Reform just decided the halacha is like R. Shimon Ben Yochai that we go by the reason for each law. This come up in Bava Metzia at the end of ch 9 and in Yevamot. And though people think we do not poskin by R. Shimon still there is a contradiction in the Rambam concerning this. And there is a long Mishna Lamelech which I think tries to answer this problem.