In cigarettes, we’ve invented a deadly vice that is immune to natural selection and our own reasoning. They’re not the only product we’ve built with those characteristics. — The series “Guidance Systems” discusses technologies that seem to improve our lives by offering us new choices, while in fact shaping or removing our ability to decide things for ourselves. At the age of 14, Sean David imagined becoming a doctor. “I wanted to be Marcus Welby,” he remembers. So…