Wishful thinking is making decisions according to what might be pleasing to imagine instead of according to evidence or rationality. When attempting to justify such thinking, an alternative term such as "faith" may be used.

Studies have consistently shown that, holding all else equal, subjects will predict positive outcomes to be more likely than negative outcomes.

Prominent examples of wishful thinking include:

• Economist Irving Fisher said that "stock prices have reached what looks like a permanently high plateau" a few weeks before Black Thursday in 1929, which helped to trigger the Great Depression
• Paul Wolfowitz predicted "an explosion of joy will greet our soldiers" in the run-up to the 2003 Iraq War
• President John F. Kennedy believed that, if overpowered by Cuban forces, the CIA-backed rebels could "escape destruction by melting into the countryside" in the Bay of Pigs fiasco

A similar phenomenon is the availability heuristic.