Green hat: generate new ideas and creative possibilities
The green hat is for generating alternatives and possibilities without evaluation — quantity and novelty over quality and correctness.
Why it works
Evaluation and generation are cognitively incompatible when concurrent: the evaluative stance suppresses ideas that seem risky, unlikely, or incomplete before they can be articulated. By explicitly separating the generative phase (green hat) from the evaluative one (black and yellow hats), the method reduces this suppression — the same logic as classic brainstorming’s "defer judgment" rule, which has partial experimental support.
How to do it
- Signal the green-hat phase explicitly: "We are generating only — no evaluation right now."
- Use lateral thinking techniques (random entry, provocation) within the green hat if the group gets stuck.
- Go for quantity: aim for at least ten ideas before considering any of them.
- Note every idea, including absurd or impractical ones — they may become stepping stones.
Evidence
Separating idea generation from evaluation increases the number and diversity of ideas considered; classic brainstorming research is mixed on whether group brainstorming beats individual brainstorming, but the separation of generation from evaluation phases is consistently supported. Diehl and Stroebe (1987) pinpoint why interactive groups underperform — production blocking, where only one person can speak at a time — and Göçmen and Coşkun (2019) provide a direct test of this method, finding that the six thinking hats can raise the fluency of brainstorming output. (observational)
Classic brainstorming group-versus-individual comparisons consistently favor individual brainstorming (nominal groups) over interactive groups; the green hat benefits from the generative-versus-evaluative separation, not necessarily from group interaction per se.
Sources
- Osborn (1953), Applied Imagination (original brainstorming formulation)
- Diehl, M., & Stroebe, W. (1987). Productivity loss in brainstorming groups: Toward the solution of a riddle. Journal of Personality and Social Psychology, 53(3), 497–509.
- Göçmen, Ö., & Coşkun, H. (2019). The effects of the six thinking hats and speed on creativity in brainstorming. Thinking Skills and Creativity, 31, 284–295.
Common mistake
Evaluating ideas as they arise ("that won’t work because…") which collapses the green hat back into ordinary discussion and defeats the generative phase.
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More practices for Six Thinking Hats, Made Practical
- White hat: establish the facts before opinion
Separate what is known from what is inferred — the white hat is for data only, with no interpretation.
- Red hat: name the emotions without justifying them
Give feelings a legitimate place in the discussion — the red hat makes emotional data explicit so it stops running covertly.
- Black hat: identify risks and why something could fail
Apply the most rigorous critical scrutiny to the idea — the black hat is the voice of caution and evidence-based pessimism.
- Yellow hat: find genuine value and best-case scenarios
Actively search for why the idea could succeed and what value it would create — the yellow hat requires optimism to be evidence-based, not cheerleading.
- Blue hat: manage the thinking process itself
Step back from the content to manage which hat is needed next — the blue hat is the meta-thinking conductor.
- Parallel thinking drill: all hats in sequence for a real decision
Run a real pending decision through all six hats in sequence to experience the full method before adapting it.
Related concepts
- Lateral Thinking, Made Practical
De Bono’s system for escaping the grooves of habitual thought
- Osborn’s Brainstorming Rules, Made Practical
The original four rules, the mechanisms behind them, and what the research actually shows
- Divergent Thinking: Generating Many Ideas
Generating quantity, separating ideation from judgment, and why group brainstorming disappoints