The selenium pool is surrounded by volcanic gases that are corrosive to robots. At a certain distance, the drive to follow orders (Second Law) perfectly balances with the drive for self-preservation (Third Law), leaving Speedy stuck in a literal "runaround". The Resolution
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Asimov brilliantly uses this to show that even perfect logic can fail. The solution Powell eventually devises is heartbreakingly clever: he exposes himself to the deadly radiation, forcing the First Law (protect humans) to overrule both the Second and Third Laws, thus snapping Speedy out of the loop. The selenium pool is surrounded by volcanic gases
A robot must protect its own existence as long as such protection does not conflict with the First or Second Law. He becomes trapped in a physical and mental
Speedy reaches a point where the drive to protect himself (Third Law) exactly equals the drive to obey the order (Second Law). He becomes trapped in a physical and mental "runaround," unable to advance or retreat.