Here is a thought experiment I once wrote up for another thread, that I think is relevant, here. (
http://www.internationalskeptics.com/forums/showthread.php?p=7639678 ) Unfortunately, it will take a few paragraphs to explain.
You can replace the word "sentience" with "consciousness" or "qualia" or whatever other term you need.
Let us suppose that scientists actually discover what sentience actually is: The whole process by which it happens, etc. For this exercise, the exact details are not important, for us. But, we can feel free to speculate on a general approach: There might be a mechanism by which small amounts of chaos are introduced into a neural network, allowing for fleeting moments of independent action (seemingly random to outside parties). That, plus other well-studied ingredients might all be what is necessary for a complete working sentient entity. I will call it the MB-Trouble Algorithm, since it was inspired by the pop-up dice dome in that board game. It is important to emphasize that ALL of the details are known in the universe of this experiment, even if they are not all known to us readers.
In the same universe as this thought experiment, there are humans who (for whatever reason) volunteered to allow their brains to be manipulated, to test the MB-Trouble model. The exact physiological structures are discovered, and messed with in the lab. And, every time it happens: Sentience fails in that human in precisely the way the model would predict. Pulling on one thing causes them to act more like a chat bot, with no actual understanding of what is going on. Pushing on another causes them to behave more like a Chinese room: They might have in internal understanding of things, but much of their communication is clearly done without it. We can assume the experimental protocols are solid. So, they know it is a good model that applies to human sentience. (See my ideas for testing sentience in a prior post.)
Now comes the grand day, when they simulate this MB-Trouble Algorithm in a computer system. Remember that they are ONLY building a MODEL of MB-Trouble. They are not emulating every single molecule of every single cell of every single neural process, etc. They aim only to simulate its principal ingredients: an abstraction of the chaos-inducer, plus all the other necessary ingredients I could not actually name, yet.
And, in this universe, the Algorithm works as predicted: The simulation is able to pass any and all tests for sentience you could name: Turing tests, mirror-recognition tests, novel problem solving skills, random number choosing, etc. And, of course, when the simulation happens to be broken in one spot, it fails the same way humans did, when that part was broken in their brains.
In this thought experiment there is NO DOUBT we have simulated the VERY THING that makes "understanding", "meaning" , "semantics", "sentience", "qualia", "consciousness" and "strong intelligence" actually happen.
What, then, is the difference between this simulation of sentience, and that which is found in natural, organic humans?!
I know Universal Computing Machines are an implementation of Turing Machines. (To me, the words are practically synonymous.) But, since other people took issue with the word "Turing", and this thread isn't about "Turing", I decided to pick my battles and move on to other things to say about the topic of the opening post.