It depends on what problem you are talking about. Something as general as 'numbness', has a multitude of specific underlying causes; to treat those causes you n

It depends on what problem you are talking about. Something as general as 'numbness', has a multitude of specific underlying causes; to treat those causes you need specific solutions. If you believe that psychotherapy can be effective in treating underlying causes, as I do, than individuals who have helped develop different specific psychotherapy methods have treated (directly & indirectly) causes on a mass scale.