Asimov's Laws of robotics

*In 1985 he added an extra law to be at the top of the list, the Zeroth Law.
0. A robot may not harm humanity, or, by inaction, allow humanity to come to harm.
1. A robot must not harm a human in any way, or allow a human to come to harm in any way through inaction.
2. A robot must obey humans orders, unless they conflict with the first law.
3. A robot must protect its own existence, unless it conflicts with the first or second laws.
This explains just having 3 laws… https://xkcd.com/1613/

https://farrbott.substack.com/p/asimov-4-laws​