The Three Laws of Robotics and Zeroth Law

The Three Laws of Robotics are a set of rules devised by Isaac Asimov, one of the most famous science fiction authors. The rules were introduced in his 1942 short story Runaround. The Three Laws are:

• A robot may not injure a human being or, through inaction, allow a human being to come to harm.

• A robot must obey the orders given to it by human beings, except where   such orders would conflict with the First Law.

• A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

These form an organizing principle and unifying theme for Asimov's robotic - based fictions, including his Robot series. Many of Asimov's robot-focused stories involve robots behaving in unusual and counter-intuitive ways as an unintended consequence of how the robot applies the Three Laws to the situation in which it finds itself. Other authors working in Asimov's fictional universe have adopted them and references, often parodic, appear throughout science fiction as well as in other genres.

The original laws have been altered and elaborated on by Asimov and other authors. Asimov himself made slight modifications to the first three in various books and short stories to further develop how robots would interact with humans and each other. In later fiction where robots had taken responsibility for government of whole planets and human civilizations, Asimov also added a fourth, or zeroth law, to precede the others:

The 0th Law

In the chapter "The Duel" in Robots and Empire, Asimov first presents another law, which he calls the Zeroth Law of Robotics, and adjusts the other ones accordingly:

0. A robot may not harm humanity, or through inaction allow humanity to come to harm.

1. A robot may not harm a human, or through inaction allow a human to come to harm, unless this interferes with the zeroth law.

2. A robot must obey orders given to it by a human being unless such orders interfere with the zeroth or first laws.

3. A robot must defend its own existence unless such defense interferes with the zeroth, first or second laws.

The Three Laws, and the zeroth, have pervaded science fiction and are referred to in many books, films, and other media.