Seventh Thinking Hat? What is 'Wisdom' Anyway?
John Waters, Director, United Kingdom
A convenient definition of "wisdom" can be found on Wikipedia: "a deep understanding and realization of people, things, events or situations, resulting in the ability to apply perceptions, judgements and actions in keeping with this understanding.
It often requires control of one's emotional reactions (the "passions") so that universal principles, reason and knowledge prevail to determine one's actions. Wisdom is also "the comprehension of what is true or right coupled with optimum judgment as to action."
This seems to me what the 6 thinking hats are there to guide participants towards - assuming that the blue hat can be applied effectively to manage the other modes.
Introduction of the grey hat (as described above) seems to me to add nothing useful to help a group of minds, each built from very different experience and conditioning, to achieve an acceptable shared conclusion or solution. Indeed, it might re-inject some of the uncertainty identified and removed by the other hats.