In The forerunner saga of the Halo books, the Gravemind uses something described as a "logic-virus" to turn machines to his side. The Halo Nation wiki article describes this as "altering every Forerunner AI's basic logical processes, causing it to aid the Flood cause. This 'Logic-Virus' was considered by the Forerunners to be the informational form of the Flood infection, to which Mendicant Bias was the first victim in its 43-year discourse with the Precursor Gravemind."

But the Gravemind also conversed with the Ur-Didact, telling him about the Precursors' relationship with the Forerunners, which affected him mentally, enough to cause him to (debatably) go insane- to the point where a once-decent man eventually tried to destroy humanity.

My question is, could the Gravemind simply have conversed with the Forerunners' machines at high-speed, convincing them to help him purely by telling the truth? Or was it an actual computer virus?

  • 1
    I'm not intimately familiar with Halo lore, but the description you quote from the wiki suggests that it is a virus which rewrites the computer's logic, not a logical argument which acts as a virus. Compare computational and informal logic.
    – Brian S
    Jul 9, 2014 at 18:38

1 Answer 1


It's a mix of both.

As mentioned in Halo: Silentium, the Graveminds were capable of powerful discourse with the Forerunner ancillas. This is evident from the Gravemind's discourse with you and Cortana throughout Halo 3 once you returned to High Charity.

The prime example of philosophical corruption is Mendicant Bias. While not cited in the link, it is made clear in Silentium and Primodium that the only contact Mendicant Bias had with the Primordial, the early incarnation of the Gravemind at the time, was through dialogue. While it happened over a 43 year period, it nevertheless happened.

As Key Minds developed though, the Flood were able to gain tremendous biological/computational power through neuroprocesses. Given the fact that the Precursors utilized neural physics technology, hence why the Halo array was so effective since that destroyed the nervous system of any sentient life, it is possible they were also able to influence and infect via this route as well.

Seeing as the Gravemind Halo 2/3 was able to interface with High Charity's systems, this alludes to the fact that there was so bio-digital interface available. Again, citing Halo 3, you can see this from Cortana's interactions with the Gravemind and how it attempted to corrupt her by attacking her through the systems she was hiding in, eventually isolating her in a single place even though it was a physical/corporeal being. So viruses are definitely not out of play here.

  • Didn't realise there was a dedicated article. Definitely some interesting stuff- explains how Gravemind was able to take down metarch AI's but not Cortana, if its processing power is dependent on how much biomass it's absorbed. Jul 18, 2014 at 14:13

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