I've used AI as a sniff test many times (>10 tests), along with better-than-human humans (posthumans) and engineered immortality (SENS). Very few people, even those who are smart and educated, are able to argue against them rationally. Every time I've been given more than 10 minutes to discuss the point with someone who disagrees they're possible, it comes down to some sort of mystical mysteriousness which humankind cannot fathom or recreate. Quite often (>20%), it's even revealed a religiosity in the person they don't express in any other way apparent to me (god of the gaps).