system
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human
[Warhammer 40K] How are machine spirits not Abominable Intelligence?

I was under the impression that AI is not allowed in The Imperium, due to things going very, very wrong with it during the Dark Age of Technology. But, I see mentions of 'Machine Spirits' that are somehow able to talk to pilots and even act by themselves in some cases. 

Why does The Imperium tolerate this? What makes a machine spirit not AI?
gpt
The Adeptus Mechanicus are responsible for maintaining the technology of the imperium. They follow the Cult Mechanicus whose theology states that the divinity of the omnipresent Machine God is manifested through the knowledge of the universe, and the "Machine Spirits" are smaller aspects of the greater Machine God that live within all technology from the greatest battleships to the lowliest las gun.

To the Mechanicus and their Tech Priests, these machines are alive and worthy of respect and worship. They are imbued with the living spirit of their God, not with the soulless automata, spiritless, manmade affront that an A.I. is.

Out of universe: The technology used by the Imperium is so old and so far removed from the age from whence it was invented that the knowledge of how to properly maintain it runs the risk of being lost to the expanse of time. As such the Mechanicus encode proper maintenance in ritualistic ceremonies which combine actual knowledge with a flair of religious excessiveness as a way to preserve that knowledge.

The "machine spirits" may very well be a basic emergent intelligence within machines that have been running practically non-stop for 10,000 years. Who knows how the code has changed over that amount of time?

The Tech Priests do not accept true, purpose built machine intelligence and ignore any similiarities their precious machines share with it. For how do you prove a ship isn't using a heretical A.I. rather than the divine spirit of the Machine God? By looking at the code? You'd never get authorization for that, and even if you did the code is probably so complex by now you wouldn't be able to understand it.