The Witnesses

What most children have been taught and believe as truth.
Almost everyone growing up hears or reads The Night Before Christmas, in which Clement Clarke Moore claims to have personally witnessed Santa Claus commit an act of reverse burglary in Moore's home:
He was chubby and plump, a right jolly old elf,
And I laughed when I saw him, in spite of myself;
Clement Clarke Moore is usually thought of as an honest family man, who would not lie to countless children across several generations. Numerous parents have also told their children that they have seen Santa come into their homes on Christmas Eve, but these adults carefully explain to their children that Santa has only been seen after the children have gone to sleep.
Despite such claims about needing to go to bed before he appears, some children also report seeing Santa in person---sometimes in flagrante delicto with one of their parents:
I saw Mommy kissing Santa Claus
Underneath the mistletoe last night.
And of course hundreds of thousands of children believe they have actually had their photograph taken with Santa Claus at the mall or other places.

Santa also is alleged to make personal appearances at highly public venues, such as the Macy's Thanksgiving Day Parade or numerous street corners at holiday time.
With all this impressive evidence, the child's argument goes, surely at least some of these sightings must be real. Not all of these witnesses could simply be mistaken or lying or crazy. And most of all, why would an adult tell a child he or she had seen Santa if it wasn't true? Why would grown-ups lie to little kids?
CRITIC'S ARGUMENTS
Significant details and problems that most children are not aware of.
* Clement Clarke Moore's reliability as a witness is dubious. A Visit From St. Nicholas was originally printed anonymously. It was only after he was pressured by his children that Moore claimed to have given this statement. Additionally, textual analysis has indicated that someone other than Moore likely wrote the statement. This makes Moore's claim to have seen Santa Claus in person highly questionable.
* I Saw Mommy Kissing Santa Claus was written by a 13 year-old boy and was initially banned by the Roman Catholic Church. Since the Catholic Church has an interested in promoting both "Christ's Mass" and visions of saints (i.e., St. Nicholas), the Catholic Church's skepticism of this teenage boy's account is curious. Further, the claimed witness, Jimmy Boyd, was also a popular musician at the time he gave his account, suggesting that he may have simply made up a song about seeing Santa for commercial purposes.
* Malls, parades, charitable organizations, and even the White House are known to hire men to pretend to be Santa Claus during the holidays (sometimes involving professionals hired to portray Mrs. Claus and/or elves as well). Many adult men groom themselves and take on other purported physical characteristics of Santa Claus in order to hire themselves out for this role.
* The bones of St. Nicholas are kept in a Catholic church in Bari, Italy. Since St. Nicholas is known to be dead, it is improbable that the person children and other alleged witnesses believe they are seeing is in fact St. Nicholas, a.k.a. Santa Claus.
Witnesses to other legendary characters.
While many children claim to have met Santa Claus in person, keep in mind that in the modern world, children also claim to have met the following characters in person: Darth Vader, various superheroes, Elmo and Cookie Monster, and Barney the dinosaur. It is known for a fact that Darth Vader, super heroes like Spiderman and Batman, and Muppets like Elmo and Cookie Monster are fictional characters. Moreover, dinosaurs have been extinct for over 65 million years, and theropod dinosaurs did not drag their tails on the ground, as Barney is seen doing. Thus, it is highly unlikely that Barney is a real tyrannosaurid, as portrayed to children. Moreover, the fact that you can pay people to dress up like these characters to appear at parties or other events suggests that the "Santa Claus" children have met and/or had their picture taken with is also a normal person being paid to pretend to be Santa.
Witnesses to other amazing events.
Although some children will tell their peers that they have personally seen Santa Clause come down the chimney in their house, children are also known to relate stories about meeting dragons and monsters and other fantastical encounters. Children also sometimes say that the floor in their homes is made of hot lava. Since hot lava poses serious health risks to humans, not to mention the potential legal liability a building contractor would face by building a house with hot lava for floors, it is extremely unlikely that hot lava has ever been used as a building material in someone's house, notwithstanding the accounts related by many children to the contrary.
Reliability of children as witnesses.
In common law, children were historically presumed to be incompetent to testify if they were below a certain age. Even today, although the presumption that children are per se incompetent has largely been abrogated, establishing the competency of a child witness requires special care. This is because children are generally known to be easily influenced and to sometimes have difficulty discerning reality from things they have imagined.
How should it have been done?
If Clement Clarke Moore really was a witness of Santa Claus, it is troublesome that he initially published his account anonymously (assuming that he in fact wrote that account). One would expect him to have told other people about this remarkable event immediately. Yet there are no records or affidavits from him until long after the claimed event.
Similarly, in the case of Jimmy Boyd, there is no record of his father divorcing his mother over her alleged adultery with Santa Claus. Further, Jimmy Boyd knew that his father had cataracts, making it unrealistic for him to expect his father to have been able to see the intimacy between his mother and Santa. Far from having a problematic marriage, Leslie Boyd worked hard and sacrificed for his family, suggesting that Jimmy's mother would remain faithful to her husband, rather than breaking her marriage vows with a corpulent, bearded individual from the North Pole. Instead of submitting his account to academic journals or established news outlets, Jimmy Boyd shared his account of seeing Santa on venues like The Ed Sullivan Show, implying that Jimmy Boyd was making up a story for money rather than trying to proffer serious evidence for the existence of Santa.
Analogy
If some little kid came up to you and swore up and down that he really saw Batman, what would you think? Is it more reasonable that Bruce Wayne is a real person who fights crime dressed up as a bat? Or that this kid saw something and assumed in his childish naïvété that it was the "real" Batman?
Responses to these issues by apologists.
In a famous newspaper editorial, a little girl named Virginia allegedly wrote a letter to the editor asking if Santa Claus was real. We will leave it to readers to consider the plausibility of a little girl writing a newspaper editor to ask a question like this. In any case, the New York Sun printed an editorial, notably unsigned, presenting the ad hoc argument that Santa has some kind of metaphysical nature, which contradicts the physical manifestations claimed by the alleged eyewitnesses. The Sun's apologetic relied heavily on the canard that "absence of proof is not proof of absence."
"Not believe in Santa Claus! You might as well not believe in fairies! You might get your papa to hire men to watch in all the chimneys on Christmas Eve to catch Santa Claus, but even if they did not see Santa Claus coming down, what would that prove? Nobody sees Santa Claus, but that is no sign that there is no Santa Claus. The most real things in the world are those that neither children nor men can see. Did you ever see fairies dancing on the lawn? Of course not, but that's no proof that they are not there. Nobody can conceive or imagine all the wonders there are unseen and unseeable in the world."
Additionally, both adults and children have invented an apologetic theory that all of these various "Santas" who make public appearances are actually "helpers" for the real Santa, and thus the fact that you can pay an impostor to defraud children is asserted as evidence in favor of the existence of a real Santa Claus.
Another theory was presented in the 1947 apologetic film, Miracle on 34th Street. This theory suggests that Santa is real based on the mere fact that children believe he is real. This is a classic example of circular reasoning. Note: the courtroom scene in this film also relies on a factual error, in which a judge permits hearsay testimony from children as evidence that Santa is real---"Thomas Mara, Jr. testifies that his father had told him that Santa was real and that 'My daddy wouldn't tell me anything that wasn't so. Would you, daddy?'" Under the rules of evidence, such testimony would not be admissible to prove the truth of the matter asserted.
Critic's response.
Really? Really?
Conclusion
We at Santa Claus Think have never met a sane person over the age of 12 who seriously believes he or she has seen Santa Claus in person, or that anyone else has, either. The only reason a rational adult would believe that someone has really seen Santa Claus is that he or she is desperately clinging to a fantasy because it makes him/her feel good, and because he or she was raised to believe it without examining the evidence.