In an interview with BJ Fogg, Ramit Sethi states that persuasion is ok as long as it is done ethically. He proceeds to define ethical persuasion as persuasion that is done to get a person to do A, when they would have done A anyway if they had all the information and the necessary motivation. If they had all the information and motivation and would not have done A, then it would be unethical to pursuade them to do so. I understand the point he is making, but disagree that pursuasion is ethical in this scenario.
I think Mr. Sethi is implying that if somebody would lose weight, or try to get rich if they had the information and motivation, it would be ethical to pursuade them to do so. But, consider the example where the person being persuaded would do something horrible, like murder, if they had all the information and the motivation to do so. Since they don't have the information or the motivation, they do not commit the crime, and it would not be ethical to pursuade them to do so. In fact, it would be very wrong to persuade them. Further, there are things people may do if they had the information and motivation that would not be very good for themselves. To give an example, one may go party all the time, getting drunk, having fun, and ignoring responsibilities. It sounds like a good time, but it actually holds a person back to pursuade them to do so.
My biggest contention with his statement however is that it requires the persuader to make a judgement on what a person would do given a certain set of hypotheticals. It is impossible for the persuader to know this. It is possible to make an educated guess, and for friends and family members, it may be more appearant than for others, but to make this judgement on a complete stranger (or for someone you know) is not practical or ethical. To say a person would do x if they knew y would require an extensive knowledge of that person's psychology, biology, and circumstances. Even if these things were known, deduced, or induced, there is still a great amount of variability that would come into play with an individual's choice. It's like saying, "those republicans would choose to be democrats if they had all the information and motivation, so I'm going to pursuade them." One's personal bias will color the perception of the targeted person.
What persuasion really is, is the ability to impart your will onto another person, and the discussion of whether persuasion is ethical should revolve around this question. There may or may not be circumstances under which it is warranted. Regardless, one should be aware that persuasion exists and is being used constantly to try to shape one's behavior. Despite the ethical considerations, persuasion is an important art/science to learn if for no other reason than to recognize when it is being used against you.