A belief that the experienced world is the worst possible. It describes a general belief that things are bad, and tend to become worse; or that looks to the eventual triumph of evil over good; it contrasts with optimism, the contrary belief in the goodness and betterment of things generally. A common conundrum illustrates optimism versus pessimism with the question - does one regard a given glass of water as: "Is the glass half empty or half full?" Conventional wisdom expects optimists to reply with half full and pessimists to respond with half empty, but this is not always the case.