Just peeked in on the list, having come to its central position by my own means, from the artificial intelligence position that simulated minds can be conscious of their own existence.
Chapter 7 of my recent "Robot" <http://www.frc.ri.cmu.edu/~hpm/book97> derives the idea that all universes are equally real from the position that robots can be conscious. It notes that the totality of all universes (like the library of all books) requires no information to construct, that, although any of us (however we define ourselves) exists in an infinity of bizarre universes, we're most likely to find ourselves in ones that require the least amount of initial information to explain us, and that we are stuck on a subjective path that needs the least coincidences to keep our consciousness going (and that turns out to be the boring physical universe that made us by Darwinian selection, all working under a very simple TOE that resulted in the visible universe as a side effect). It also notes that, no matter what happens to us, among all universes there are some in which our consciousness continues, and we will always find ourselves in those (and never in ones where our consciousness does not continue!). For some things that happen (like our brain rotting) the simplest continuation of our consciousness may no longer involve the exact continuation of the old physical laws. Here's a compactified presentation of of the core train of thought: Start with the premise (A) that properly designed minds implemented in computers can have conscious experiences just like minds implemented in flesh. Also assume (B) that experiences of rich virtual worlds can be as vivid as experiences of the physical world. Immersive video games make the second premise non-controversial. Materialistic accounts of the evolution of life and intelligence, providing a rough roadmap for the evolution of machine intelligence, make the first premise compelling to AI guys like me. (Also, Occamesque, it demands no mysterious special new ingredients to make consciousness.) Let AI = Artificial Intelligence and VR = Virtual Reality. Combine the two halves of both premises into four cases: 1) a flesh human in the physical world. 2) a conscious AI controlling a physical-world robot. 3) a human immersed in a VR, maybe by neural interface. 4) a conscious AI linked to a VR, all inside one computer. Case 4 is a handle on the subjective/objective problem that was not available to past philosophers. Unlike flesh, dreams, stories, sensation-controlling demons or divine ideas, it is nearly free of slippery unstated assumptions about human minds or physical reality. On the outside, we have a simple objective device stepping through states. Yet, on the inside, there is a subjective mind experiencing its own existence. What connects the internal experience to the external mechanism? As in any simulation, it is an interpretation. Storage locations can be viewed as representing bit patterns, numbers, text, pressures, temperatures, sensations, moods, beliefs, feelings or more abstract relationships. In general, different observers will have different interpretations. Someone looking at the simulation trying to improve memory management in the operating system will likely put a different interpretation on the memory contents than someone wanting to view life in the simulation, or to talk with its inhabitant. But does the AI cease to exist if there is no one outside who happens to have the correct interpretation to see it? Suppose an experimenter sets up an AI/VR, and builds a translating box allowing him to plug in and talk with the AI. But on the way home, the experimenter is killed and the translating box destroyed. The computer continues to run, but no one suspects it holds a living, feeling being. Does the AI cease to be? Suppose one day enough of the experimenter's notes are found and a new translating box is built and attached. The rediscovered AI then tells a long story about its life in the interval when it was unobserved. My take on this is that there is an observer of the AI even when it goes unobserved from the outside, namely the AI itself. By interpreting some process inside the box as a conscious observer, we grant that process the power of making observations about itself. That self-interpretation exists in its own right whether or not someone outside ever appreciates it. But once you allow externally undiscovered interpretations of AIs that exist only in their own eyes, you open the door to all possible interpretations which contain self-aware observers. Which is fine by me. I think this universe is just such a self-interpretation, one self-defining subjective thread in an infinity or alternatives that are just as real to their inhabitants.