The “Slicing Problem” for Computational Theories of Consciousness

A thought experiment called the "Slicing Problem" challenges substrate-neutral computational theories of consciousness, such as Integrated Information Theory, by imagining a water-based computer whose gates and connections can be cleanly halved to create two identical computers running the same computation, with the slicing reversible via a switch without changing the amount of matter. The problem asks how different theories would count conscious entities as the switch toggles: a token interpretation yields two discrete conscious units, while a type interpretation may yield only one. Both options lead to either allowing consciousness-multiplying exploits or requiring ambiguous boundaries between conscious entities, raising philosophical and ethical questions. The authors discuss resolutions for theorists unwilling to accept such exploits and specify three features that may help physicalist theories navigate these issues.

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Abstract

The “Slicing Problem” is a thought experiment that raises questions for substrate-neutral computational theories of consciousness, including those that specify a certain causal structure for the computation like Integrated Information Theory. The thought experiment uses water-based logic gates to construct a computer in a way that permits cleanly slicing each gate and connection in half, creating two identical computers each instantiating the same computation. The slicing can be reversed and repeated via an on/off switch, without changing the amount of matter in the system. The question is what do different computational theories of consciousness believe is happening to the number and nature of individual conscious units as this switch is toggled. Under a token interpretation, there are now two discrete conscious entities; under a type interpretation, there may remain only one. Both interpretations lead to different implications depending on the adopted theoretical stance. Any route taken either allows mechanisms for “consciousness-multiplying exploits” or requires ambiguous boundaries between conscious entities, raising philosophical and ethical questions for theorists to consider. We discuss resolutions under different theories of consciousness for those unwilling to accept consciousness-multiplying exploits. In particular, we specify three features that may help promising physicalist theories to navigate such thought experiments.