«وَلَكِنَّهُمَا أَيْ إِنْ وَإِذَا لِتَعْلِيقِ أَمْرٍ هُوَ حُصُولُ مَضْمُونِ الْجَزَاءِ بِغَيْرِهِ»
Both in and idha attach the occurrence conveyed by the response to another occurrence.
Taʿliq does not automatically mean that the condition is the sole sufficient physical cause of the response. At this stage it states a rhetorical dependence: the occurrence of the condition is made the reference for presenting the response.
Example: «إِنْ جِئْتَنِي أَكْرَمْتُكَ» — If you come to me, I will honor you. Coming is the condition, and honoring is the response tied to it.