Rambam on Rational Judaism
Rambam had to defend the use of tefillin against the heretical Karaites "enlightened" literal approach to the Torah and rational Judaism, claiming it wasn't necessary. This is just one of many issues with using purely logic in Torah observance. Rabbi Yaron Reuven says that in the face of struggles and tests like Avraham and Yitzchak had to face, rational approach to Judaism doesn't work.
