I pondered the question of whether a person was alive or not when I was
much younger, particularly because I knew so many people in my
corporate environment who didn't seem alive to me.
By alive I mean having something that gets you excited, being spontaneous, enjoying life.
But I wanted a more rigorous definition of being alive. So I conceived of the animatronic Lincoln life-sized doll that was at Disneyland at the time. I imagined doll-Lincoln programmed with everything Lincoln was known to have said, particularly answers to questions. Then I asked myself how a friend of the real Lincoln's would have known the difference between the alive Lincoln and the life-sized doll?
My answer was: to know that Lincoln was alive he would have to be capable of saying or doing something unexpected. That is a rigorous definition of being alive.
The validity of that definition became clear when my granddaughter was given, for Christmas, the very lifelike dog robot (photo on the right) that could do 90% of what a live dog can do.
My granddaughter made the robot perform a dozen pre-programmed behaviors for an hour. Then she went off to play with the real dog.