Question: You seem to be saying that AI programs will be virtually identical to people, then. Won't there be any differences?
Speculation: Probably the differences between AI programs and people will be larger than the differences between most people. It is almost impossible to imagine that the "body" in which an AI program is housed would not affect it deeply. So unless it had an amazingly faithful replica of a human body -- and why should it? -- it would probably have enormously different perspectives on what is important, what is interesting, etc. Wittgenstein once made the amusing comment, "If a lion could speak, we would not understand him." It makes me think of Rousseau's painting of the gentle lion and the sleeping gypsy on the moonlit desert. But how does Wittgenstein know? My guess is that any AI program would, if comprehensible to us, seem pretty alien. For that reason, we will have a very hard time deciding when and if we really are dealing with an AI program, or just a "weird" program.
Question: Will we understand what intelligence and consciousness and free will and "I" are when we have made an intelligent program?
Speculation: Sort of -- it all depends on what you mean by "understand". On a gut level, each of us probably has about as good an understanding as is possible of those things, to start with. It is like listening to music. Do you really understand Bach because you have taken him apart? Or did you understand it that time you felt the exhilaration in every nerve in your body? Do we understand how the speed of light is constant in every inertial reference frame? We can do the math, but no one in the world has a truly relativistic intuition. And probably no one will ever understand the mysteries of intelligence and consciousness in an intuitive way. Each of us can understand people, and that is probably about as close as you can come.
[From Gödel, Escher, Bach; 679-670.]