A Critique on the Theory of the Necessity of the Oneness of Consort (Faḥl)

Among the causes for the prohibition of marriage is fosterage, which is one of the most important issues of concern. There is consensus among the jurists of all the Islamic schools in that fosterage is one of the causes of prohibition. However, the issue disagreed upon is whether the source in fosterage causing the spread of sanctity (ḥurma) is the mother (murḍi‘a = foster mother) or the father (ṣāḥib laban = possessor of milk). The renowned majority of Imāmīs believe that what is valid in the spread of sanctity in fosterage is the oneness of the consort (faḥl); and their reason is (based on) the traditions that cause specification and limitation of several generalities, such as the Prophet’s (S.A.W) ḥadīth, “What is prohibited through fosterage would be prohibited through parentage (nasab), too”, and the verse of the Qur’ān, ﴾your [foster-] mothers who have suckled you and your sisters through fosterage﴿. (Al-Nisā’, 23) The renowned disapproving majority’s statement is that of Ṭabarsī, the author of Tafsīr al-Bayān, and another group of the Imāmīs, who have not considered as a precondition the oneness of consort in the fosterage causing the spread of prohibition. The reason for this statement is the generality of ḥadīth, inclusiveness of the verse, and the traditions of Muḥammad b. ‘Ubayda. The critical review of the two viewpoints and their reasons reinforce the unrenowned majority’s statement.