Early Asimov. 1957. The 3Laws and humans with phobias conditioned by their lack of exposure to 'others' ways. Bailey is from Earth where the fear is of living on the surface. Solaria is ALL surface living. However, it is so under populated, that Solarians fear physical closeness, having so seldom even seen another Solarian face to face. Chores and caretaking of infants are done by their many robots after all. So how could one get close enough to another to bludgeon them to death?