Emotional yet Rational

When reading Chapter 9 of Fogg’s Persuasive Technology, the idea of an ethical issue arising because of computers’ lack of emotions struck me as odd. I completely agree with Fogg that we are “emotional beings.” However, I feel that we are also, for the most part, rational and logical beings. Thus, are we really at a disadvantage to a piece of machinery? Do we really “expect ethical persuasion to include elements of empathy and reciprocity” when coming from a computer?