The opposite of pessimism, optimism is a lifeview where one looks upon the world as a positive place. Optimists generally believe that people are inherently good. They have a "positive" outlook on life, believing that given time, things will work out in the end. A common example used to illustrate optimism is: given a glass that has been filled halfway, is it half filled? Or half empty?
See also, Is the glass half empty or half full