We have all read about Michele Bachmann's claim that a woman believed her daughter became mentally retarded as a result of getting the HPV vaccine. In reaction, researchers offered a huge cash prize for proof that this was true (http://www.pri.org/stories/health/cash-offered-for-proof-to-back-up-bachmann-hpv-story5959.html). Why could they confidently offer such a huge prize for confirmation of this story?
In view of the Principles of Scientific Thinking described by Lilienfeld, what would proof of this story entail? First, since there has been no published link between the HPV vaccine and mental retardation, this is an extraordinary claim. Any evidence of proof would have to be very strong. Obvious rival hypotheses include that the person had undiagnosed mental issues prior to taking the vaccine, or that a known cause of mental retardation was responsible. Occam's razor tells us that these simpler explanations are more likely. Any conclusions would have to be replicable. Since many people have received the vaccine, we would expect to see other cases. Even if a correlation were observed between the HPV vaccine and mental retardation, we know that correlation does not imply causation. An experiment would have to be performed in order to conclude that the HPV vaccine actually caused mental retardation.
In light all this, the researchers offering the prize could have safely offered much more than $10,000!