كَحَرَكَةِ الْيَدِ تُوجِبُ حَرَكَةَ الْمِفْتَاحِ
As the movement of the hand leads to the movement of a key.
For the Muʿtazilī account, this illustrates effects that occur in another subject through an act performed with human capacity. The Sunni reply accepts the observed connection while denying that natural necessitation and independent creation are identical.
The key’s rotation is not the hand’s movement; it is a separate event in another subject. To claim the cause produces the effect necessarily by itself adds an assertion about independent causal power to the mere report of sequence.