system
Given the following post, respond as if you're commenting on Reddit:
human
[sci-fi] How can you tell when AI is sentient?
gpt
You actually hit on a very difficult question to answer and a more recent "hot" area in philosophy. If interested look into the philosophy of mind and consciousness with maybe a close look on weak and strong A.I. 

To answer your question in a somewhat unsatisfactory way, we don't know.