In the mid-1980s, a serial rapist terrorized elderly women in a Pittsburgh suburb. After investigations, interviews, and leads failed to turn up anything, police chief Chris Kelly consulted a psychic. “What did we have to lose,” he asked, “We’d tried everything else.”

What they had to lose were time and resources. But it’s his second line I want to focus on. The failure of traditional police methods was irrelevant to whether consulting a psychic was a valid option. Instead of having the psychic come up with a suspect, why not just grab a random man on the street? To justify the random man, psychic, or any other new method, one needs evidence that it would work. The police chief in this case employed a non sequitur form of reasoning.

This is a common occurrence with alternative medicine patients. Lack of success from traditional methods is insufficient reason to treat one’s backache with tachyon water and jasmine crystals.

Non sequitur sightings are also frequent in the Intelligent Design world, where an organism’s complexity is presented as proof that God did it. But just because a scientific explanation hasn’t been found doesn’t mean one doesn’t exist. That would be like saying persons in the 18th Century who considered flight impossible were correct since it wasn’t being done at the time. Besides, if an eye or a mollusk’s protection is so complex as to necessitate a designer, whatever created it would have to be more complex than what it created, so the creator would have to a have a creator, as would that creator, ad infinitum.

We’ll now move on to the false dichotomy, but stick with the God stuff. Skeptic Andre Kole related the story of meeting a Christian magician who showed him a tract he had written entitled “Jesus: Magician or God?” Kole explained this was a false dichotomy. Jesus could have been neither a magician nor a god. Perhaps he was a great leader with excellent organizing skills, distinctions requiring no supernatural explanation. Or maybe he was embellished, fraudulent, loony, manufactured, or misquoted.

Kole read the tract and credited the author with making a good case that Jesus was not a magician. But it certainly didn’t follow that Jesus was therefore a deity. The frustrated author then asked why so many biblical prophecies had come true, thus employing a pair of logical fallacies: Moving the Goalposts and Appealing to Ignorance.

We move now to the regressive fallacy, which is the failure to take into account natural fluctuations. Stock market prices, golf scores, and chronic back pain inevitably go up and down. A person seeking relief from a throbbing elbow through chiropractics, magnetic belts, or chi-infused falafels is likely to do so when the pain is at its worst. If the pain lessens, the method will be credited, but it may be due to the natural fluctuations. This demonstrates the value of controlled double blind tests under strictly defined conditions. The plural of anecdote is not data. We need scientific tests, not testimonials, to gauge a medicine’s effectiveness.

We’ve beat up on alternative medicine and creationists enough, let’s address a logical fallacy common among conspiracy theorists. Proportionality bias is the belief that extreme events must have extreme, probably sinister, causes. It is a telling feature that there are seldom conspiracy theories surrounding something that failed. After substantial digging, I could only find a couple of sites that argued for a conspiracy surrounding the Ronald Reagan assassination attempt. And these gained no traction and were of little interest among the conspiracy minded. Even one of the more extreme sites, beforeitsnews.com, though sympathetic to the idea, noted that “there is no smoking gun.” (I guess John Hinckley’s didn’t count). But if Hinckley had succeeded, imagine the zeal with which conspiracy theorists would pounce on the idea that an obsessive, greatly disturbed lone gunman did the deed.

Then we have recency bias, which is placing more emphasis on what has happened lately and thinking it will continue. Many an amateur investor has fallen prey to this one, your blogger included. It’s easier to think current momentum will continue rather than bothering to analyze trends. Yet one year before advent of the Internet, personal computer, or cell phone, few persons would have foreseen these devices.

Our brains have evolved to react more strongly and quickly to threats and fear than to flattery and soothing. This makes us vulnerable to negativity bias. Condoleezza Rice took advantage of this when she glossed over the total lack of evidence for weapons of mass destruction and pronounced this ominous vision: “The smoking gun of evidence for WMDs in Iraq could come in the form of a mushroom cloud.”