Copernicus, Aristarchus and Kepler were delusional because they said the solar system revolved around the sun. Pythagorus was delusional because he said the world was round. Alfred Wegener was delusional because he said continents were slowly drifting apart. Gregor Mendel was delusional because he said traits are passed through generations of living things. If we stop letting people share their "delusional" ideas, or challenge the status quo, we will become trapped in a monotonous echo chamber void of creativity and progress.