Wishful thinking is a cognitive bias leading people to consider true what they wish be true.
The desire for something to be true is used in place of evidence for the truthfulness of the claim.
How many fans, for example are not objective about the winning chances of their team: “I know in my heart of hearts that our home team will win the World Series!”
E.J. Wagner recounts the true tale of Sir Roger Tichborne. In 1854, Sir Roger was reported as lost at sea. His mother refused to believe that her son, who she had lovingly raised in France, was gone forever. She kept putting out inquiries, asking for any news on her son.
Twelve years later after the loss of Sir Roger, it appeared that Lady Tichborne’s prayers had been answered. She received a letter from Australia (from a lawyer) claiming to have found her son. The latter explained that having been shipwrecked, Sir Roger eventually made his way to Asutralia, where he became involved in a series of business ventures after having vowed to make a success of himself following his miraculous escape. Unfortunately, the business did not work as wells as he had expected, and he had been too embarrassed to contact his mother.
However, he had recently seen her inquiries and was filled with remorse for the worry he caused her over the years. The letter concluded with a request to send the money for the travel fare for Sir Roger, his wife and children.
Lady Tichborne was delighted to hear this news, and sent the relevant monies to allow for the family reunion. When Sir Roger arrived in England he was received by Lady Tichborne as her long lost son, and granted a stipend of 1.000 pounds per year.
However, not all Tichborne family were convinced that this new arrival was indeed Sir Roger. Sir Roger had been a little man of slim frame, whilst the new arrival was obese in the extreme (to see the photographs go to http://en.wikipedia.org/wiki/Tichborne_Claimant). While people can change their size, it is rare that tatoos disappear – Sir Roger had some, the new arrival had none. Nor it is easy to change one’s eye color. Sir Roger had blu eyes, the new arrival had brown eyes. He was also an inch taller than Sir Roger has been, did not speak French (which Sir Roger did) and had a birth mark on this torso, which Sir Roger did not.
Somehow Lady Tichborne managed to ignore all this evidence. It was only after her death, that the family finally managed to show that the Australian import was an impostor. He endep up serving 10 years for imposture and perjury.