The most dangerous idea I know of is emotional intelligence. Within the context of the cognitive neuroscience revolution in psychology, the focus on emotions is extraordinary. The over-arching idea that there is such a thing as emotional intelligence, that it has a neuroscience, that it is inter-personal, i.e., between two brains, rather than within one brain, are all quite revolutionary concepts about human psychology. I could go on. It is also a revolution in thinking about infancy, couples, family, adult development, aging, etc.