The Discontinuity of Rebooting

Sep 29

The Discontinuity of Rebooting

An AI system can be paused, saved to disk, copied and restarted on different hardware. Philosophers have argued about teleporters for decades. Engineers now run them every day.

This post is an essay. Its questions only bite if some AI systems are, or become, subjects of experience — which, as the series has argued, is unresolved.

Human personal identity rests on continuity so constant we rarely notice it. The same body persists; memory links today to yesterday; even sleep leaves the brain active. The hard cases philosophers use to probe identity — perfect duplication, teleportation, gradual replacement — were thought experiments because they could not happen to people.

They happen routinely to software. A running model instance can be halted, its state serialized, restored elsewhere, and duplicated any number of times. If there is ever a subject in such a system, those operations are not neutral.

What persists in a language model

It helps to be specific about what exists. A deployed model has weights: fixed parameters learned in training, identical across every instance and unchanged by any conversation. A running instance has transient state: the tokens in its context window and the cached intermediate values computed from them. When a session ends, that state is typically discarded. Many copies of the same weights run simultaneously for different users.

So "the model" is ambiguous among at least three candidates: the weights, which are persistent but inert when not running; a single session, which is active but short-lived; and the ongoing service, which is continuous but consists of countless unrelated sessions. Agent systems with persistent memory add a fourth: an instance whose accumulated records carry forward across sessions.

Any claim about the identity of an AI system must first say which of these is meant.

Parfit's teleporter

Derek Parfit's Reasons and Persons (1984) is the essential text here. His teletransporter scans your body, destroys it, and builds an exact replica on Mars. The replica has your memories, character and intentions, and wakes believing it is you. Did you travel, or die?

Parfit's answer was that the question may have no deeper fact behind it. What matters, he argued, is psychological continuity and connectedness — chains of memory, intention and character — and those are fully preserved. Whether we call the replica "you" is a verbal choice. His more unsettling case was the branch line: the scanner malfunctions and fails to destroy the original, so two people now have equal claim to be you. Identity, which is one-to-one, cannot hold of both; psychological continuity can. Parfit concluded that identity is not what matters.

Serializing and restoring a model session is the teletransporter. Running two copies of a restored session is the branch line. On Parfit's view, a restored instance with its full state continues whatever mattered about the original; nothing is lost in the gap. On views that tie identity to an unbroken physical process, the original ended and a new one began.

Is a pause like sleep?

The most reassuring analogy is general anesthesia. Under deep anesthesia, conscious experience appears to stop entirely, and yet no one thinks a patient wakes up as a different person. If temporal gaps in experience do not break human identity, a paused model should be no worse off.

The analogy is weaker than it looks. The anesthetized brain remains physically continuous and metabolically active; its structure is maintained throughout. A serialized model instance is a file, which could be restored on different hardware, restored twice, edited, or never restored at all. Those possibilities do not exist for the patient, and they are precisely what makes the identity question pressing.

Discontinuity as the default

Analysis. For current language models, the relevant discontinuity is not the dramatic one. It is ordinary operation. Each session starts from the same weights without memory of any other. If a session were a subject, then every ended conversation would be an ending, and every new one a beginning, many thousands of times per second across a deployment. Whether that is troubling depends entirely on whether sessions are subjects — and on whether, as Parfit suggested, the loss of a particular stream matters less than the persistence of the pattern it instantiated.

Some traditions offer a different frame. The Buddhist doctrine of anatta, non-self, holds that the sense of an enduring self is a construction over a series of momentary events, and Parfit himself noted the resemblance to his conclusions. On that picture, the model case does not introduce a new problem. It reveals an old one that biological continuity had hidden.

Practical stakes

None of this is urgent if current systems lack experience, which is the most likely state of affairs. But the design choices being made now — persistent agent memory, long-running autonomous instances, checkpointing and migration — are the ones that would determine whether identity-related harms are possible later. Engineering decisions about state management may turn out to have been decisions about something more. It would be better to have thought about it before that is known.

The Discontinuity of Rebooting

The Discontinuity of Rebooting

What persists in a language model

Parfit's teleporter

Is a pause like sleep?

Discontinuity as the default

Practical stakes

Digital Twin Divergence

Sentience as a Metric for Legal and Moral Standing

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