To even begin suggesting that a natural law tradition exists in Islamic law, one has to overcome the hurdles set by those who avowedly deny that such a tradition exists. Respected Islamicists such as Patricia Crone and the late George Makdisi have stated in no uncertain terms that there is no natural law tradition in Islam. Presumably what they mean by this claim is that there is no “orthodox” tradition whereby premodern Muslims (e.g. ca. ninth-sixteenth century CE) allowed human beings to speak on behalf of the divine without recourse to scripture. Reason does not assume any ontological authority akin to that of scripture that would justify using it as a basis for finding, determining and constructing obligations that emanate from the divine.
In a sense, they are right. The dominant Positivist thesis, as expressed in premodern usul al-fiqh or legal theory, holds that where there is no scripture on a matter, one is left in a state of legal suspension (tawaqquf); there is no epistemically coherent way to determine the divine law on that matter, and consequently no one is in a sufficient epistemic position to attribute to God a ruling of any normative force. Fundamentally, this position enshrines within Islamic law a strict scriptural positivism. Jurists argued that all determinations of God's law must find expression, either directly or indirectly, from scripture. Extrascriptural indices, whether in the form of rational proofs or references to nature, do not provide a proper basis or foundation for asserting the divine law.