From al-Ash`arī's "Vindication of Kalām"

This is a very interesting statement that al-Ash`arī makes when defending the practice of kalām against those who argue that it is a needless, unimportant, irrelevant, or misleading innovation (bid`a) because the Prophet said nothing about it.

"But when new and specific questions pertaining to the basic dogmas arise, every intelligent Muslim ought to refer judgment on them to the sum of principles accepted on the grounds of reason, sense experience, intuition, etc. For judgment on legal questions which belong to the category of the traditional is to be based on reference to legal principles which likewise belong to the category of the traditional. And judgment on questions involving the data of reason and the senses should be a matter of referring every such instance to (something within) its own category, without confounding the rational with the traditional, or the traditional with the rational."

(p. 131, The Theology of al-Ash`arī, translated by Richard J. McCarthy)

It seems that al-Ash`arī considers the intellectual world to be sharply divided between reason and tradition, with each having its own domain of operations. Let's see how well that intuition holds up as I continue to read. I can sense one wrinkle already: how does one come to agree on what, precisely, the "tradition" constitutes? Only the Qur'ān? The Qur'ān and the Sunna? Are all the various madhhabs of jurisprudence included in this? And so on. I'm very eager to see how this turns out.