The effective causes of rulings:
Here, the effective cause is synonymous with wisdom. Linguistically, it means a cause: one says, “this is the illah of that”, meaning its cause.
Al-Amidi (d. 631 AH) therefore said: “The effective cause originally means the motive, that is, something that contains a wisdom suitable to be intended by the Lawgiver in prescribing the ruling.”[1]
Al-Shatibi (d. 790 AH) said: “By effective cause we mean the wisdoms and benefits to which commands or permissions relate, and the harms to which prohibitions relate. Hardship is the effective cause of permitting the shortening of prayer and breaking of the fast while travelling; travel is the circumstance designated as the cause of that permission. In sum, the effective cause is the benefit or harm itself, not its presumed locus, whether apparent or unapparent, objectively delimited or not.”[2]
[1] Al-Ihkam, 3/202. Its annotator, Shaykh Abd al-Razzaq Afifi, may God have mercy on him, preferred that, out of proper reverence for God, the “motive” in relation to Him be expressed as the purpose of prescribing the ruling.
[2] Al-Muwafaqat, 1/410-411.
I say: in the discussion of analogy, legal theorists distinguish between effective cause and wisdom. The effective cause is the apparent, objectively delimited attribute by which the ruling is identified. Wisdom is the ruling’s purpose of securing a benefit or averting a harm, and may or may not be objectively delimited. Thus, the effective cause of shortening prayer is travel, an objectively delimited matter, whereas its wisdom is averting hardship, which is not objectively delimited. The ruling is therefore attached to the effective cause, not to the wisdom.