Courage is important to being rational. You will not be very rational if you are too scared to act differently to the people around you, or too scared to even think about very big ideas-- these are the two main threads touched on in this tag.
Related Tags: Fallacies, Groupthink, Heroic Responsibility, Heuristics and Biases, Motivated Reasoning, Rationalisation, Self-Deception
More thorough explanations of the importance of courage can be found here and here. Suggestions for how to improve or become more courageous in this sense can be found here and here....