Let us begin like this:
A researcher in what we call Strong AI (AI for Artificial Intelligence) tells you his goal is to produce non-biological human life, that is, a human being that has no biological components. He advises you that biology does not a human being make and that by the dawn of the 21st century, it will be a post-biological world, at least as far as human beings are concerned.
Startled, you protest, "I can't conceive of humanity as being anything other than biological! A machine is a machine and a human is a human and they are built of different substances and they are not the same thing."
So he smiles (condescendingly perhaps, since he is well used to this sort of reaction to his life's work and knows exactly how to counter it) and says he would like to present a scenario to you.
Suppose, he says, your son, whom you love, is in a terrible car accident and badly burned and mangled, yet still manages to survive. The year is 2032 and the technology is available to rebuild his body inside and out. Instead of spending the rest of his life deformed, in pain and paralyzed from the neck down, he can have his life back again in full health.
So using silicon, fluids, microchips, computer components and all sorts of synthetic material your son is rebuilt or re-created or - the researcher's favorite word - refreshed. Not only that, although you are aware your son has been restored using non-biological material, when you finally see him after weeks of "restorative surgery" he looks just like he has always looked - same face, same smile, same hug, same laugh. The doctor tells you he is 75% non-biological and 25% biological, but you can't tell the difference. They even put components in his brain to replace damaged tissue and he acts just like your son - he is your son! Even though he is more synthetic than biological.
Now, asks the researcher, is your son still human?
Well, you respond, if you put it that way - that it's him, his mind and personality are intact, even his endearing and irritating quirks are there - yes, of course he's still human. Just like the person with a metal plate in his head or leg is still human. Just like the person with an artificial heart or kidney or eye is still human. Restoring his body using non-biological materials doesn't change the fact this is the same son I held in my arms at birth and taught to ride a bicycle at seven.
So, says the researcher, if he's still human at only 25% biological, why wouldn't he still be human at 15% biological, or 10%, or 5% or 0% biological?
Wouldn't he still be your son? Still a human being?
Even if his body no longer consisted of blood and bone and skin and his brain no longer consisted of grey tissue and grey matter?
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