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 David Chalmer’s “Fading Qualia” thought experiment.
Nick Bostrom Ph.D. is Professor of Applied Ethics at Oxford University, the Director of the Oxford Future of Humanity Institute, and co-founder and Senior Fellow of the Institute for Ethics and Emerging Technologies, and founding chair of the World Transhumanist Association (Humanity+).