We know that the way we phrase questions can have substantial effects on our opinions and behaviors, often without us being aware of it. An example of this phenomenon is the topic of an article by Sarah Moore, David Nealb, Gavan Fitzsimonsc, and Baba Shivd (2011) entitled Wolves in sheep’s clothing: How and when hypothetical questions influence behavior. In it they show that, under certain circumstances, responding to hypothetical questions can shape your future judgment and behavior. The authors say that hypothetical questions are essentially wolves in sheep's clothing because they may seem quite innocent but in the way they are phrased can influence us without us realizing it.
Here is an example. In one of their surveys the researchers asked respondents if learning a politician had been convicted of accepting a bribe would make them less likely to vote for that person. Alternatively, they asked another group of respondents if learning a politician had refused to accept a bribe would make them more likely to vote for that person. Although the question had been purely hypothetical, the negative question resulted in 37 percent of respondents being less likely to vote for the 'convicted' politician. The positive question found 83 percent of respondents more likely to vote for the 'honest' politician. The researchers add that when people are aware of the potential effects of hypothetical questions, they can correct their biases and say that public education is needed to raise awareness of how hypothetical questions can sway our actions.
Hypothetical questions in the solution-focused approach
I agree that it is important to raise awareness of the manipulative potential of hypothetical questions. This way we may learn to protect ourselves from being manipulated for commercial, religious or political purposes. But I do not think that hypothetical questions are always evil necessarily. Solution-focused professionals ask their clients specific types of hypothetical questions, too. But these questions do not manipulate clients in the direction of some commercial, religious or political goal but in the direction of the client's own preferred future. An example of such a question is the miracle question: "Suppose that tonight, when you are asleep, a miracle happens which would solve your problems. When you'd wake tomorrow how would you know the miracle would have happened?"
When is the use of hypothetical questions morally defensible?
Whether using hypothetical questions is ethically right or wrong depends on to what ends you use them. Consciously manipulating people in a direction you actually think would be bad for them is of course morally wrong. Manipulating people in a direction they think is wrong for them but you think is right for them is dubious at least. Only the subtle manipulation of people in the (positive) direction of their own choice is morally defensible.