Extraordinary claims require extraordinary evidence

Carl Sagan is attributed with saying that extraordinary claims require extraordinary evidence. I will start by providing a definition for the word evidence. The best definition I found for this word was in wikipedia as follows: http://en.wikipedia.org... Evidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either a) presumed to be true, or b) were themselves proven via evidence, to demonstrate an assertion's truth. Evidence is the currency by which one fulfills the burden of proof. Note, BTW, that we are not talking about absolute proof, which exists only in the abstract world of mathematics. In reality we can't really prove anything, the person reading these lines right now may be hallucinating and what he is experiencing in fact is not real, therefore he can't prove the lines he is reading now really exist, or even that he exists. So when we speak of evidence we are speaking of data that is used to convince someone of a claim but not absolutely prove it. Nothing in this world is absolutely ever really provable in the mathematical sense. With this out of the way, we can start examining Carl Sagan's phrase. Lets start by asking what is an extraordinary claim ? Here is an example: 1. I have a pet dog 2. I have a pet alligator in my bathtub 3. I have a pet dragon that spits fire and eats knights for breakfast So an extraordinary claim is a claim that is supported by very weak, or no prior evidence or that may even contradict other available evidence. Ask yourself what is the minimal amount of evidence that would be required for you to believe each of these claims. Remember not prove them in absolute terms (which is impossible), but convince you of thier truth. I will continue to examine two cases, one legal and one scientific: Legal ------ A person is accused of murdering his wife. Here is the evidence presented by the prosecution: - There are two apparently credible eye witnesses saying they saw him do it and describe how he did it - A day before the event took place the wife found out the husband was having an affair, she threatened the husband she will divorce him and destroy his reputation - The accused has no alibi during the time in which the event took place. Now the prosecution has a very strong case, and unless defence can somehow dispute these claims, the accused will, most likely, be found guilty. Now lets replace the accusation with the following: A person is accused of casting a spell on his wife and turning her into a cat. Now the same amount of evidence exists, we have the witnesses, the motive and the opportunity. Lets even add in some more evidence: - A cat is brought to court room and and the eye witnesses confirm this is the cat she was turned into. (hence you have a body) - The accused was known to be obsessed with cats (more motive) - The accused studied witchcraft for many years (more opportunity) However all this would still not be enough to even grant a single day in court. The only thing it would grant would be the end of the prosecutor's career. So in a courtroom, the resolution holds. Science --------- In this example we will examine the case of the so called star child skull. http://en.wikipedia.org... The starchild skull came into the possession of Lloyd Pye, a writer and lecturer in what he calls the field of alternative knowledge, in February 1999. According to Pye, the skull was found around 1930 in a mine tunnel about 100 miles (160 km) southwest of Chihuahua, Chihuahua, buried alongside a normal human skeleton which was exposed and lying supine on the surface of the tunnel. The skull was found to be abnormal in several aspects: - A dentist determined, based on examination of the upper right maxilla found with the skull, that it was a child's skull, 4.5 to 5 years in age. However, the volume of the interior of the starchild skull is 1600 cubic centimeters, which is 200 cmï¿½ larger than the average adults brain, and 400 cmï¿½ larger than an adult of the same approximate size. - The orbits are oval and shallow, with the optic nerve canal situated at the bottom of the orbit instead of at the back. There are no frontal sinuses. The back of the skull is flattened, but not by artificial means. - Testing in 2004 at the Royal Holloway college of the University of London revealed unexplained "fibers" in the bone of the skull and a reddish residue in the cancellous bone, neither of which are known or recorded to exist prior to the discovery. Here is evidence, that some woos, argue point to the child being of alien origin, perhaps having an alien father. Now, of course, there is additional data that is more consistent with a standard human being but the data above does appear abnormal. - Now what's wrong with this evidence ? - Why is this not convincing the scientific community ? - This is scientific evidence is it not ? - Why not say ok, this is an alien until proven otherwise ? - And finally why is the data sufficient to substantiate the claim that the skull belonged to a living creature but not sufficient to claim it belonged to a living alien creature ? After all, the skull could be a rock that only has the appearance of a skull, can it not ? Con -- these are all questions you need to answer ... Good luck.