Grammar term · Nahw · syntax
لَام التَّعْلِيل
lam al-ta'lil
Lam of purpose/reason
Nahw · syntaxSpecific particleadvanced term
In one line
The لِ of purpose — 'in order to': a harf jarr that hides أَنْ before a mudari' and makes it mansub.
Definition (modern)
التَّعْلِيلُ: بِأَنْ يَكُونَ مَا بَعْدَهَا عِلَّةً وَسَبَبًا فِيمَا قَبْلَهَا. وَمِنْ لَامِ التَّعْلِيلِ: اللَّامُ الدَّاخِلَةُ لَفْظًا عَلَى الْمُضَارِعِ.
“Purpose: that what follows the lam is the motive and cause of what precedes it. And among the lam of purpose is the lam entering directly upon the present-tense verb.”
(النحو التطبيقي)
Key words in the Arabic
عِلَّةً وَسَبَبًاa motive and cause
أَنْ مُضْمَرَةa hidden an
Understand it
The pin's definition is a direction of motive: what follows the lam explains what precedes it — سَافَرْتُ لِلْحَجِّ, the Hajj is the reason for the journey. Before a noun it is an ordinary harf jarr. Before a mudari' it keeps that jarr nature by working through a hidden أَنْ, so the verb turns mansub — and the masdar recast shows the machinery: لِتُبَيِّنَ amounts to لِلتَّبْيِينِ.
How to spot it
Recognition test
لِ + mansub mudari' where 'in order to' fits = ta'lil. Contrast lam al-amr (jazm — a demand) and the possessive jarr lam (a noun follows).
In the Qur'an
وَأَنزَلْنَآ إِلَيْكَ ٱلذِّكْرَ لِتُبَيِّنَ لِلنَّاسِ
An-Nahl 16:44 — “And We revealed to you the Reminder so that you may make clear to the people”
لِ gives the purpose of the revealing; تُبَيِّنَ is mansub by the hidden أَنْ.
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