Does 'Porches and stoops, those symbols of a vibrant social life, stopped being used as gathering places for a rather practical reason--air conditioning.' stand independently of the premise 'Air conditioning is the primary reason for the demise of outdoor gathering.', neither following nor contradicting it?
Porches and stoops, those symbols of a vibrant social life, stopped being used as gathering places for a rather practical reason--air conditioning.###Air conditioning is the primary reason for the demise of outdoor gathering.