Wishful thinking is the formation of beliefs and making decisions according to what might be pleasing to imagine instead of by appealing to evidence or rationality.

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

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.
• 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.
• Paul Wolfowitz predicted "an explosion of joy will greet our soldiers" in the run-up to the 2003 Iraq War.

Logical fallacy

In addition to being a cognitive bias and a poor way of making decisions, wishful thinking can also be a specific logical fallacy in an argument when it is assumed that because we wish something to be true or false that it is actually true or false.

For example:

The teacher gave us a difficult exam! We shouldn't have to be subjected to such stress under the course of our education.

It may be that it was uncomfortable, but that does not mean that uncomfortable things should always be avoided. Wishful thinking underlies appeals to emotion, and is a red herring.

See also

Self-serving bias may be a directly resulting cognitive bias; see the list of cognitive biases for more. Wishful thinking also plays a part in groupthink, which concerns group decision making.

The historicity of religious figures is a field that may be conducive to some wishful thinking (compare the Historicity of Jesus Christ). Wishful thinking applied to biography in general is a familiar aspect of hagiography.