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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 Stock Market Crash of 1929, which was followed by the Great Depression.
• British Prime Minister Neville Chamberlain informed the public that the 1938 Munich Agreement guaranteed "peace in our time".
• Operation Barbarossa, Hitler's plan for the invasion of the Soviet Union.
• 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.
• The U.S. invasion of Iraq, which some believed would lead to a transformation of the Middle East.

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. This fallacy has the form "I wish that P is true/false, therefore P is true/false."^[1]

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.

Atheists argue that much of theology, particularly arguments for the existence of God, is based on wishful thinking because it takes the desired outcome "God exists" and tries to prove it on the basis of a premise through reasoning which can be analysed as fallacious, but which may nevertheless be wished true in the mind of the believer. This would better be described as confirmation bias. Also, pseudoscience is often generated and maintained by wishful thinking about human abilities.

Related fallacies are the Negative proof and Argument from ignorance fallacies ("It hasn't been proven false, so it must be true." and vice versa). For instance, a believer in UFOs may accept that most UFO photos are faked, but claim that the ones that haven't been debunked must be considered genuine.

Self-serving bias and choice-supportive bias may be directly resulting cognitive biases; see the list of cognitive biases for more. Because of the emotional consequences of wishful thinking, emotional memory is also relevant. Wishful thinking also plays a part in groupthink, which concerns group decision making.

• A study demonstrating wishful thinking in memory
• Examples of Wishful Thinking @ Humbug! Online.

Fallacies of Irrelevance v • d • e
Absurdity | Argument from ignorance | Argument from silence | Bandwagon fallacy Bulverism | Irrelevant conclusion | Middle ground | Missing argument Proof by assertion | Straw man | Style over substance | Two wrongs make a right
Appeal to consequences:
	Appeal to force | Wishful thinking
Appeal to emotion:
	Fear | Flattery | Nature | Pity | Repugnance | Ridicule | Spite
Genetic fallacy:
	Personal attack (Appeal to motive | Guilt by association | Poisoning the well | You too) Appeal to authority (Novelty | Poverty | Tradition | Wealth) | Chronological snobbery | Etymology
Other types of fallacy