I have just finished titan death and, more then any other book I have read, it explains the process of a titan crew linking with there machine. The Titan is described as having a personality, in the book when a princeps first joins with her reaver it fights her not wanting to wake.

This description matches similar descriptions of pilots in imperial knights and to a lesser extent the purifying of tanks and other mechanicum weapons.

I know that by the time of the Horus heresy true AI has been outlawed due to some Great War that has happened in the past. But these descriptions of machines exhibiting a mind of there own seems to be a form of AI that an augmented human can then mesh with and work with. Almost like being the key to a car the AI is not able to operate or have higher thoughts of its own but it is intelligent enough to have basic needs and wants, war, sleep, feel pain and fear etc.

Have the writers of any 40k material ever discussed what these “machine spirits” are? Has there been any suggestion that actualy it is a form of AI?



  • We don't really have an exact answer for what a machine spirit is...
  • We don't really know if machine spirits are real either... I don't think so...
  • The Black Library has not definitively explained the machine spirit or the inter-connectivity of man and machine, but we do have examples such as you have read to give us a base understanding.
  • It is possible to mistake AI as a machine spirit, but that depends on the AI and the one inspecting it.

The machine spirit is not really explained very well in the 40k universe. This has a number of people in debate on what even constitutes a machine spirit. I think this also is perpetuated by Guardsman and others we read about that are not associated with the Priesthood of Mars referring to their gear as having machine spirits, without verification from a Tech Priest... I used to think it was just the more advanced machines that had automated functionality, but that is not the case.

Anything that a follower of the Cult Mechanicus would deem to have a machine spirit will have been blessed with oils and chants to keep the device's machine spirit happy. I do not remember ever reading anything about a lasgun being blessed before battle (though the cleaning kit undoubtedly has some oils that could count), but boltguns and power armour have been blessed with oils and chants before battle without question. These are not automated by any respect, which is how I previously corrected the error of my ways...

I mention the most basic technologies that can have a machine spirit to show just how vast the complexity and range of the machine spirit is. From (possibly) the lasgun, to the boltgun, to power armour, to land raiders, to titans and battle barges all these devices have a machine spirit, and the complexity between them is drastic. Basically anything that one could say, "the device failed because its machine spirit was not satisfied," that machine has a machine spirit.

Once you get into the more complex machines it gets tricky. If an automated machine is complex enough with multiple functions, perfect situational programming, and even perfect error correcting programming the machine can be trusted to operate on its own as if it were a living being. For machines like a titan or battle barge that can be interfaced directly with someone's mind and communication between the two is seamless it would be like having a conversation with another being or using their senses as your own.

Personally, I think that the idea of the machine spirit is just more of the confusion of the 40k universe and humanity trying to explain what they don't know anymore from all the knowledge that has been lost... There is no machine spirit... it stopped working because you didn't take care of it and a component failed; not because it was angry... As far as I know only the Orks have the capability of making something a reality because they believe it to be true...

A clear example would be Rynn's Might. This Crimson Fist land raider defeated an entire Ork Warband without a crew or outside direction. When it was attacked the vehicle's systems activated and proceeded to kill all the Orks outside the fortress-monastery, including the Warboss, all on its own. The vehicle itself simply functioned based upon its extremely complex programming and did what the original programmer told it to do in certain situations. However, without the understanding of why the vehicle did what it did humanity is left to the idea Rynn's Might is just another example of how impressive and capable the machine spirit is.

For humanity, if someone believes that a machine has a spirit or soul then it is not a grand step for them to think that the programming or functionality of a machine is indicative of the machine having a personality or moods; such as your character thinking that a millennia old, unknowingly complicated machine taking its time to turn on would be stubborn to wake up.

Regarding AI, there are not any known AIs in use by the Imperium. Because they were outlawed, like the men of iron, there are no known instances that currently exist. The only AI that can be addressed are xenos, like Necrons or something similar.

That said, looking at the possibility of humanity mistaking an AI for a machine spirit, it is possible, in my opinion. I have not read anything that states someone can not interface with an AI such as @TerranGaming states in his answer, but assuming such a connection is possible it would not be a stretch for someone to mistake an AI for a machine spirit.

The step below artificial intelligence is virtual intelligence, something that mimics intelligence based on its complex programming. Believing that a device has a spirit and moods, but isn't AI leaves the only option to be a VI, which is entirely accepted.

If the AI does not give itself away then the individual inspecting it would likely not suspect anything. Given how complex programming is in the 40k universe and the fact that people think machines have a spirit it seems rather likely to me that without extreme deviation from what that individual has seen before in similar machine functionality they would believe an AI to just be a more moody machine spirit...

  • Because it is a future set universe I think everyone is thinking AI means fully conscious artificial being like skynet or data. The fact is that by definition Siri and Alexa are considered to be a form of artificial intelligence and I don’t think anyone would mistake them for a higher intelligence. I do agree that a lack of understanding makes even the mechanicum mistake technology they don’t understand for a spirit. The rituals of building a titan probably include copying a computer program installing it and letting it do its thing. That AI then says “Hello Dave” and is considered a spirit. – Richard C Mar 3 at 23:18

Do the mechanicum mistake AI for machine spirits?

No i don't think so. Rather i would argue that there are real machine spirits because of the way the 40k universe works. The power of belief is a real thing in 40k and machines have a real 'spirit' because everyone believes they have a spirit and thus it becomes true. there has been a Horus Heresy book that features real AI and that displayed to be vastly different from all the other machines. Furthermore one of the reasons it not real AI is because of the effects a machine spirit can have on a human interfacing with it. In a Titan it can be that the spirit literally influences the operators emotions and behavior, this is most common with Titans and Knights. It seems that the bigger the machine the more powerful the spirit.
There are examples of lesser machine spirits which make a weapon malfunction more/less which happens more often with tanks or larger weaponry.

edit: there is a example of a low level AI along with a machine spirit in the imperial military, the space marine land raider is capable of driving and firing on its own, albeit to a lesser degree than when manned.

Warhammer 40,000: Rulebook (4th Edition), pg. 25
Warhammer 40,000: Rulebook (5th Edition), pg. 81


The Mechanicum doesn't exactly "mistake" AI for what they call a Machine Spirit. Rather, it's just another word for the same thing in some cases. There are two particular kinds of so-called "Machine Spirits", which aren't always the same thing.

When it comes to Land Raiders and certain other vehicles, the limited artificial intelligence (very limited, basically an auto-pilot or the equivalent of modern-day targeting software) that helps to control the vehicle (and in some cases is capable of fully controlling it) is referred to as a Machine Spirit because the Mechanicum literally considers it to be the vehicle's soul. Combined with the banishment of advanced AI in the Imperium and their dogmatically religious approach to technology, the Mechanicum believes technology to be divine, with every machine from a battlecruiser to a toaster to be part and parcel of the Omnissiah's domain. This is where the second kind of "machine spirit" comes in.

According to the Mechanicum, machines like a bolter, chainsword, or a toaster, which don't possess an AI of any sort, are also referred to as having a "machine spirit". These are not unlike the idea held by Feudal Japan that a sword (and many other objects) contained a spirit that needed to be properly appeased during the weapon's creation at every step from purifying the iron ore to the final presentation of the weapon to its recipient. Again, this has to do with the Mechanicum's religious attitude towards technology as a whole. Since they believe that technology is divine, it is only logical to them that every machine has a literal spark of divinity within it.

Compare the latter attitude to saying "Oh god, oh god, PLEASE work!" when you're trying to get an old engine to finally turn over after you've finished repairing it. To you, you're just expressing your hope it will work, you don't really expect God to have a hand in making it function. The Mechanicum not only does believe God will make the engine work, but believes with every fiber-optic of their being that it's the only way to make the engine work, by prayer and appeasement and ritualized devotion to the very act of turning a screw into a housing.

So in conclusion, yes in some cases the Machine Spirit is an AI. And, as a note, there's a distinct possibility that the AI used by the Mechanicum uses actual human brain tissue hooked up to arcane technology to get around the ban on creating new AI technology. In other cases, the Machine Spirit is just another example of the Medieval-like superstition that permeates the Future Space Middle Ages of the 41st Millennium.

  • I agree with your answer regarding everything but AI. Nothing in the Imperium is AI. Artificial Intelligence refers to the idea that the machine learns and can make both decisions and mistakes because it is an imitation of life. Even space marines have abandoned their posts to save their own skins... I feel like an AI would have at least once come to the same conclusion, even to a minor degree. Something that runs autonomously is just an extremely complex program, following a predetermined protocol, not necessarily an AI. – Odin1806 Mar 2 at 19:47
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    @Odin1806 Fair enough. I'm not a computer expert. But I'm still not 100% unconvinced AI doesn't exist within the Imperium. – SpaceWolf1701 Mar 2 at 21:09
  • I am far from an expert too, but I agree with you again. I shouldn't have said that nothing in the Imperium is AI, but rather nothing we know of is AI! – Odin1806 Mar 2 at 21:28
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    Hmmm, I did mention in my answer that it seems like they use human tissue for making their advanced "machine spirits". So... maybe it's not that it's an AI, per se, but an organic intelligence that's been heavily... machined over? Sort of like the neural gel packs in Star Trek: Voyager that increased computer speed, or the SS Madame De Pompadour in Series Two of Doctor Who. The way that the Titan Stormherald acts, it's not just automation or programming, it's all-but-alive in a sense. – SpaceWolf1701 Mar 2 at 22:07
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    being AI does not mean it has to be fully sentient, Siri and Alexa are considered to be AI. Reading further into Titandeath it does feel to e more and more that the engine soul that the princeps melds with is something created from what we would consider to be a computer with a sense of itself and what it is. The fact that different Legios engines behave in a different way and need a different personality of princeps also suggests that when they are built there are subtle differences to the programming making some titans more aggressive meaning they need an aggressive crew and pilot. – Richard C Mar 3 at 23:10

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