Conservatives take a sober and realistic view of the world and the people in it. They are reality-based, and put no faith in utopian schemes. Like good Aristotelians, they take the actualities of the present and the past as a reliable guide to what is possible, rather than the future-oriented fabrications of a high-flying reason cut loose from experience. They admit the reality of evil and the corruption of human nature. Liberals and leftists, by contrast, tend to believe that people are basically good and that it is only extraneous factors that corrupt them. Evil has no purchase in reality for them but is merely a word we apply to those whose beliefs and values differ from ours.
Immanuel Kant wisely wrote of the "crooked timber of humanity of which no straight thing has ever been made." For liberals and leftists, however, the warpage is not inherent in the timber but comes from without, from contingent social arrangements that can and must be changed.
People who live this delusion sometimes come to a very bad end. Performance artist Pippa Bacca is a case in point. She and a friend hitchiked from Italy to the Balkans to the Middle East in wedding dresses to promote global harmony. Just three weeks into the trip she was raped and murdered in Turkey by a driver who offered her a ride.
The refusal to face reality is a mark of the leftist who prefers his u-topian view of the world to the world.