Minds and Machines

, Volume 16, Issue 2, pp 185–200 | Cite as

Quantity of experience: brain-duplication and degrees of consciousness

  • Nick Bostrom


If a brain is duplicated so that there are two brains in identical states, are there then two numerically distinct phenomenal experiences or only one? There are two, I argue, and given computationalism, this has implications for what it is to implement a computation. I then consider what happens when a computation is implemented in a system that either uses unreliable components or possesses varying degrees of parallelism. I show that in some of these cases there can be, in a deep and intriguing sense, a fractional (non-integer) number of qualitatively identical phenomenal experiences. This, in turn, has implications for what lessons one should draw from neural replacement scenarios such as Chalmers’ “Fading Qualia” thought experiment.


Computation Mind Consciousness Implementation Duplication Fading qualia Chalmers Searle Program Probabilistic Deterministic 


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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  1. 1.Faculty of PhilosophyUniversity of OxfordOxfordUK

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