正解: BCorrect: B
水平思考は前提を疑い、視点を横にずらして多様な選択肢を生む思考法です。垂直思考（論理的深掘り）を補完する役割を持ちます。Lateral thinking questions premises and shifts perspective sideways to generate diverse options. It complements vertical (logical, in-depth) thinking rather than replacing it.
de Bono は1967年の著書で、既存の枠組みの中を論理的に掘り下げる「垂直思考」に対し、枠組みそのものを動かす「水平思考」を提唱しました。ランダムな刺激語を使う、前提を逆転させる、極端な条件を仮定するなどの技法が知られています。選択肢Aは垂直思考の説明であり、Cは直観的判断、Dは統計的な多数決に近く、いずれも「新しい選択肢を生む」という水平思考の本質から外れています。例えば航空会社が「座席の快適さ」で競うのをやめ、「移動の速さと低価格」に価値を再定義した格安航空モデルは、前提をずらした水平思考の実例といえます。In his 1967 book, de Bono contrasted vertical thinking, which digs logically within an existing frame, with lateral thinking, which moves the frame itself. Well-known techniques include random-word stimulation, reversing assumptions, and imagining extreme conditions. Option A describes vertical thinking, C describes intuitive expert judgment, and D describes a statistical majority approach; none captures the essence of generating genuinely new options. A practical example is the low-cost airline model, which stopped competing on seat comfort and redefined value as speed and low price, a classic sideways move of the premise. De Bono stressed that lateral thinking is a learnable skill, not a talent reserved for a creative few.
水平思考は発想の量を増やしますが、質の評価や実行可能性の検証を伴わないと「面白いだけのアイデア」で終わりがちです。また会議で唐突に前提を覆すと、周囲から現実逃避や単なる思いつきと受け取られる場合もあります。Lateral thinking increases the quantity of ideas, but without evaluation and feasibility checks it often ends in ideas that are merely interesting. Abruptly overturning assumptions in a meeting can also be perceived by colleagues as escapism, especially in organizations that reward incremental, defensible proposals over unconventional ones that carry personal risk.
発散（水平思考）と収束（垂直思考）の時間を明確に分け、発散フェーズでは批判を禁止し、収束フェーズで実現性・コスト・効果の基準で絞り込みます。生まれたアイデアは小さな実験で検証してから本格投資に進みます。Separate divergent (lateral) and convergent (vertical) phases explicitly: ban criticism during divergence, then filter by feasibility, cost, and impact during convergence. Test the surviving ideas with small experiments before committing major resources, and give the team a shared vocabulary so that lateral moves are recognized as deliberate technique rather than distraction.