Basically this roots in constructivism and the idea that we do not necessarily need to know the problem in order to find a solution.
Solution based therapy uses on the one hand solutions and part solutions that have worked in the past for you (even if it were just for some minutes) or other people and the miracle question, through which we catapult into a solution state and discover its essence and aspects step by step.
If was found that focusing on solutions or what is good or rather good right now, has a strong positive and practical power. When there were no places left for the family therapy, people were asked to make a list of what is good or rather good in their life, and what they would rather keep the way it is. This change of focus had brought to the clients in the waiting time for a therapy place already so much benefit, that they started to research this in more detail.
With the miracle question we jump ahead into the future, basically the next day, and imagine that all the problems have been resolved (hence a miracle!) and the client is asked to oberserve step by step after awakening the next day, what is different (in themselves or others etc). This may bring up totally new aspects and parts of solution, a different point of few, attitude, feelings and thoughts. And of course a change in behaviour. It is though important and helpful to go through this wonder-full vision very detailed in order to grasp as many aspects of life and relationships as possible.