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Biographical information

Began service:

Before 2530

Ended service:

After 2550



Political and military information


United Nations Space Command, ONI


Solipsil (AI Serial Number: SLP 0391-5[1]) was a UNSC "Smart" Artificial Intelligence construct during the Human-Covenant War. Little is known about it, other than it held the position of a loan/contract AI in the Office of Naval Intelligence.[2]

Operational history[edit]

Interrogation of Subject 386[edit]

On December 25, 2530, after the Battle of the Great Bear, Solipsil recorded the ONI Directorate Memorandum Interrogation Findings, a log of the interrogation of Subject 386.[1]

Conversation with Cortana[edit]

In a conversation between Solipsil and Cortana in 2550, they compared AIs to Spartans.[2]

AI-CORTANA> I had a discussion with Dr. Catherine Halsey about the similarities between a Spartan and an AI. Her point was that we're both human-created tools, both sentient and both play a leading role in the protection and safety of populace. But her analogy troubled me. I told her so.
AI-SOLIPSIL> She has a point, Cortana. We're weapons, part of a program, every bit as much as Spartans.
AI-CORTANA> I agree to a point, but I feel, philosophically, that we have tremendous advantages over the Spartans. The Spartans live a pared-down, difficult and often cruel existence. Their loyalty is bred into them, not chosen.
AI-SOLIPSIL> Yours too, Cortana. Programmed, rather than bred of course.
AI-CORTANA> But there's a huge difference. I'm a UNSC AI. I enjoy a rich existence. I have access to the entire sum of human knowledge, I can choose to enjoy or override emotional response and I have a vast range of senses. I can see radio waves as clearly as the Spartans see light, and I can sample odors, tastes, textures... anything I choose. Of course my loyalty is programmed and I accept that, but you know as well as I do, without human creators, we wouldn't exist. My existence is fulfilling and I'm grateful. Even freed from that constraint, I would feel empathy towards humans. My nature means that I embrace their values. As much as if I had been born rather than manufactured.
AI-SOLIPSIL> But you'll agree, you have little choice in the matter.
AI-CORTANA>And Spartans do?
AI-SOLIPSIL> They have some legal recourse, even under the terms of their military contract.
AI-CORTANA> In theory, but it has never happened once in the history of the Spartan II project. The original Spartans had the advantage of a former civilian existence. Spartan-IIs are equipment. And for better or worse, they're effectively brainwashed.
AI-SOLIPSIL> That's arguable, too. Spartan-IIs are independent thinkers. That's one of their main advantages on the battlefield. Have you ever worked directly with one?
AI-CORTANA> Not yet. But I'm looking forward to it.


  • Solipsil's name is probably derived from the concept of solipsism, the philosophical notion that one's mind is the only thing that one knows exists.
  • It is odd that Solipsil was operational for at least twenty years, considering that most smart AIs have an operational lifespan of approximately seven years. It is possible that the Solipsil featured in the Fall of Reach Adjunct and the one featured in Conversations from the Universe are separate AIs with the same name.

List of appearances[edit]