|A dirty dozen gems about|
|Not just a river in Egypt|
Wishful thinking is basically attempting to claim that something is true because you've thought about it and would prefer it to be true. Unfortunately (or fortunately, if some people were to have it), the world doesn't work that way. Wishful thinking is often synonymous with denial. It's a common tactic of people who deny evolution exists or deny that climate change is happening "because the majority of people say so".
 In public policy
Wishful thinking may characterize popular consensus on other important public policy issues. For example, American space policy is now in the grip of the belief that private firms will finance the exploration of outer space. That is highly unlikely but feels good because it offers an escape from spending the large sums necessary for human space exploration. Historically only states are willing to accept the unrecoverable costs of opening geographic frontiers through sustained exploration and economically subsidized development and settlement.
 Positive outcome bias
 Positive thinking versus wishful thinking
Wishful thinking is not the same thing as "positive thinking," or the idea that by thinking positively, one will experience better outcomes. Thinking positively can help a person achieve a particular goal, in much the same way that thinking negatively can be a demotivating factor; thinking positively can conceivably help someone to maintain their focus on getting some task done. Wishful thinking, on the other hand, is more about changing reality to match your perceptions, or thinking that reality would be swayed by what you think.
An apt analogy can be found in medicine. Thinking positively about a course of treatment can improve a patient's outlook on life, helping the patient to feel better and maybe even having a placebo effect. Meanwhile, wishful thinking would entail denying that one had an illness, or that God would cure it, and assuming it would go away just because of that.
 See also
- Argument from adverse consequences
- Law of Attraction
- Magical thinking
- Willful ignorance