Six Thinking Hats is Parallel Thinking
The Six Hats method is one simple and practical example of carrying out 'Parallel Thinking', described first by de Bono in his book with the same name. (published by Viking, London and Penguin Books, London).
With the traditional argument or adversarial thinking (established by Socrates, Plato and Aristotle), each side takes a different position and then seeks to attack the other side.
With parallel thinking, both sides (or all parties) are thinking in parallel, in the same direction. There is co-operative and co-ordinated thinking. The direction itself can be changed in order to give a full scan of the situation. But at every moment each thinker is thinking in parallel with all the other thinkers. In the final stage the way forward is 'designed' from the parallel thoughts that have been laid out.
PS: Do not confuse this with Lateral Thinking, another concept by de Bono.