Princeton University historian Michael Gordin has been researching pseudoscience for a new book, and he has good news and bad for those scientists determined to keep their pursuit free of imposters. The good part is that scientists should take the proliferation of pseudoscience as a compliment. It's because the public respects and even reveres science that so many fakers and wannabes clothe themselves in scientific trappings.

 The bad news is that pseudoscience can't be eradicated. "It's not a pathogen or a germ that we can cure from American culture," he said. "It's more like a cancer." If scientists try to emphasize some distinguishing trait of science, pseudoscientists will try to copy it. If being published in a peer reviewed journal is important for science, then pseudoscientists will create their own peer reviewed journals devoted to ESP, creationism, or cold fusion. If testability is the key, the pseudoscientists will claim to have passed one.

Gordin's book is called The Pseudoscience Wars: Immanuel Velikovsky and the Birth of the Modern Fringe, and as the title implies, he centers his case on one particularly charismatic 20th century peddler in pseudoscience.

Though Velikovsky is largely forgotten today, he was the author of a 1950 super-bestselling book, Worlds in Collision, which put forward the idea that in 1500 B.C., Jupiter spat out a comet, which upset the Earth's axis and later became the planet Venus. The book attempted to make the case that this solar system reshuffling caused various mythological catastrophes, such as the parting of the red sea in the Bible.

Gordin used Velikovsky's astronomical tall tale to assess the way scientists distinguish themselves from fringe elements and other outsiders. Many scientists, he said, embrace the concept known as falsifiability. The idea comes from a philosopher of science named Karl Popper, who defined scientific ideas as ones that could be tested and potentially proven wrong.

Einstein, for example, passed Popper's test with flying colors. He made several specific predictions regarding relativity – one of the most famous being the bending of starlight by the sun, which was observed during an eclipse.

Gordin isn't sold on falsifiability as a universal test of science, though he concedes it is powerful and smart. "It captures our intuition," he said. When people weasel out of arguments by changing or adding on to their theories ad hoc, he said, it feels like cheating. Most of us feel frustrated and cheated when we're trying to argue with people who react to every counterexample by reshaping their ideas or inventing special exceptions as they go along.

Popper, said Gordin, felt just such frustration with Freudian psychotherapy. Proponents came up with an exception or new rule to encompass anything that seemed to disprove that it worked. "This enraged Popper," said Gordin. By showing there was no test that could ever disprove it, Popper demonstrated that psychotherapy wasn't rigorous enough to count as science.

This is not to say that psychotherapy is useless, said Gordon. Before Freud, people were categorized as either sane or insane, and Freud introduced the modern idea of mental health as a continuum. Freudian psychology is full of weird, unscientific ideas, but parts of it represented an advance over what people previously believed.

And alas, said Gordin, Popper's falsifiability idea is losing its potency. Since the need to pass tests or make predictions is the current gold standard of science, pseudoscientists are now devising tests and predictions. Earlier this year, for example, the proponents of a brand of creationism known as "intelligent design" claimed a victory after the results of a new analysis of human DNA called the ENCODE project.

Scientists have known for some time that most of our DNA isn't part of any gene, and for years they didn't know what this non-coding DNA did, if anything at all. Some scientists called it "junk" though that term has been losing favor as additional studies are revealing functions for some of it. The ENCODE study was the most complete to date, and continued the trend by finding signs that even more of the mystery DNA might do something.

Once this was announced, the intelligent design proponents started to claim victory – they'd predicted that God wouldn't design human DNA full of useless "junk" and here, they said, was the proof. The obvious problem with the Intelligent Design prediction is that it's too easy. Anyone might guess that the closer scientists look, the more functions they might find for our little-explored portions of DNA.

Something almost identical happened with Velikovsky's idea, though his prediction wasn't quite such a no-brainer. In fact, Gordin found correspondences showing that it was Albert Einstein who inadvertently prompted Gordin to come up with a test. Improbably, when they both lived in Princeton, New Jersey, the famous scientist and pseudoscientist were friendly. Einstein, said Gordin, told Velikovsky that because his idea didn't predict anything, it wasn't real science.

And so, wanting to be a real scientist, Velikovsky came up with a prediction. Venus, he said, should be hot – hotter than expected considering its proximity to the sun. He turned out to be right, not, of course, because Venus was a comet ejected from Jupiter in 1500 BC, but because it has a thick atmosphere and is heated through the greenhouse effect.

Gordin said that while Velikovsky's idea incorporates some elements of Biblical literalism, he called creationists pseudoscientists, and they, in turn, said he was too far on the fringe for their taste.

Still, Velikovsky's popularity had a long,-steady run, said Gordin. His Worlds in Collision and subsequent books kept selling through the 1950s and his appeal rose during the 1960s and 1970s. Young counterculture types loved his far-out ideas. Velikovsky became a source of worry and annoyance for a number of top scientists. Physics Nobel laureate Murray Gell-Mann, for example, made public statements denouncing Velikovsky for seducing young people away from real science and thereby threatening American technological dominance.
Carl Sagan, too, took the popularity of Velikovsky seriously enough to attempt to debunk him, even entering into a debate during a 1974 meeting of the American Association for the Advancement of Science. But by the 1980s, however, Velikovsky and his colliding worlds faded from the scene.

Gordin was the featured speaker for a recent meeting of the Philadelphia Association for Critical Thinking (PhaCT) – a skeptics' society here, and he told the audience that there's never likely to be an easy universal test to distinguish science from pseudoscience. Intelligent Design, astrology, cold fusion and UFO sightings are all pseudoscientific for different reasons. They can all be debunked case by case, but not as a package deal. Testability is still important, he said, but has to be considered alongside scientific consensus and other factors, none of which are fool-proof alone. As long as there's science, pseudoscience will follow like a shadow, but then, he said, "you can't get rid of a shadow except by turning off the light."