One of the most persuasive themes in literature is that of the artificial servant. In his 1921 play "RUR," Karel Capek named his artificial servants "robots," from the Czech word robota, which roughly translates as "unwilling worker." (It could also mean "someone who does boring work.") That name has stuck with us ever since, and despite other names--android (human-shaped artificial being), cyborg (cybernetic organism, implying part machine, part living tissue), droid, and so on--robot is likely to be the definitive label for some decades to come.
Isaac Asimov began writing his robot stories in the 1940s, and published the first compendium volume, I, Robot, in 1950. The Three Laws of Robotics first appeared together in Asimov's story "Runaround," published in Astounding Science Fiction in March of 1942. In a conversation in December of 1940, Campbell presented the rules to Asimov as a fait accompli, saying that he had abstracted them from principles made obvious in the stories themselves.
Later, the Three Laws became key to plot development in the robot stories, and as Asimov merged his robot stories with his Foundation stories and novels, the Three Laws played a significant role there, as well. Today, they are taken for granted--by science fiction writers and robot designers alike.
The Three Laws seem almost self-evident as guidelines for any variety of artificial servant--at least, servants capable of moving around or otherwise taking significant action. Thus, while a modern thermostat (a particularly simple kind of robot) has neither the complexity nor the power to save or harm a human, the onboard computer of a spaceship may. (Asimov was indignant that the HAL 9000 computer in Kubrick and Clarke's 2001: A Space Odyssey failed to follow the Three Laws! Clarke and Kubrick, however, implied that a programming contradiction caused Hal to malfunction, and that was the root cause of Hal's murderous behavior.)
A completely mobile metal servant in humanoid form, as envisioned by Asimov, is mythic. Robot servants of this type have existed at least since Homer (see footnote). Even before Asimov's first robot compendium, Eando Binder (the writing team of Earl and Otto Binder) had written a story called "I, Robot," later dramatized on the 1960's television series The Outer Limits. But Asimov gave the robots an endearing personality, a feckless but determined sense of honor and dignity that has not been equaled since.
It's not at all extreme to call Asimov the father of the modern robot, just as his character, Susan Calvin, is the fictional mother of the robots. Calvin, of course, creates the science of robotics--a word that Asimov coined, and which has gone into general usage today.
Some of the most famous robots of the screen show a selfless fealty to the Three Laws. Robby the Robot in Forbidden Planet (1956) is beyond any doubt an Asimovian robot. The terminators in James Cameron's series of films are rather less so.
Ultimately, even Asimov himself maneuvered around the basic Three Laws. R. Daneel Olivaw, the robot colleague of detective Lije Bailey in The Caves of Steel and The Naked Sun, when faced with the extreme forces of human history, and some very difficult decisions, formulates the so-called Zeroth Law in Robots and Empire. Basically, the Zeroth law allows a robot to harm a human if it is for the expressed good of a greater number of humans, or humanity as a whole. This allows Daneel to become a behind-the-scenes manipulator of human history, a sort of one-robot Illuminati. But Asimov was well aware of the dire implications of the Zeroth Law, and was still developing Daneel's story in the last robot/Foundation novels.
Gregory Benford, David Brin, and I used Daneel in our trilogy of novels set in Asimov's Foundation universe. Daneel in these novels has become a tragic figure, neither human nor entirely robot, burdened by the weight of history. For the Zeroth law, of course, allows and even encourages robotic interpretation of circumstances, thereby implying--even requiring--that robots have the equivalent of a conscience.
To me, it seemed unlikely that Daneel would appreciate these burdens. But, as a robot, Daneel must serve...
Forever and ever.
Asimov was well aware of the myth of the Golem, an artificial warrior/protector made of clay and imbued with life in 16th Century Prague by Rabbi Löw. The Golem is instructed to protect the Jewish inhabitants of the ghetto against the depredations of anti-semitic mobs. But the Golem is too powerful and ultimately goes out of control. This is the classic version of the artificial servant story, and it is echoed in the extraordinary novel and myth of Frankenstein's monster. However, Mary Shelley's monster, assembled by a scientist from fresh corpses, is not intended to be a servant, but a new kind of human being, intellectually and physically a superman. The Monster's failure is due to another kind of programming error--the failure of Frankenstein, his creator, to follow through with a moral education, to take responsibility for this new kind of "child."
Asimov's robots are often childlike, but their programming failures usually arise through inherent contradictions in the Three Laws, or unexpected mutations, such as the development of ESP. The robots themselves, by and large, remain innocent, like perpetual children.
As for their positronic brains, it's clear that Asimov was simply looking for a new way of describing super-advanced and complicated computer circuitry. Positrons are anti-electrons. Circuits utilizing positrons would be exotic indeed. This is not to say they are impossible--just very advanced. Besides, the name sounds cool. Today, scientists are working with quantum computers that rely on the vagaries of the subatomic realm. Such computers can do computations in more than one "universe" at a time. Doubtless Asimov would have found that a very intriguing possibility.
What if a robot with a quantum logic brain could act in more than one world-line? What if, in one branching world-line, a robot must kill a human being, so that in all other world-lines, humanity will survive?
As you can see, the Three Laws can be resurrected and played with over and over again.
As always, Asimov endures, and the problems he presents to us in these stories are, in disguise, the moral problems of any thinking individual.
In the end, what intrigues us most about the robot stories and novels is the conviction that we are no better than the robots, and perhaps worse. Perhaps we are simply the servants of human history, and our discovery of the Zeroth Law led to our Fall from grace.
Are the Ten Commandments nothing more than a wordy expansion of the Three Laws?
Footnote: The Tin Woodsman in Baum's The Wizard of Oz is actually a kind of Six Million Dollar Man, since he started out as a human. As he accidentally chopped off portions of his anatomy, they were replaced by metal parts. Along the way, he would have been a cyborg!