Originally published 26 July 1999
Recently, an astronomer at the Lick Observatory in California found in the institution’s library a horoscope cast by the 17th-century astronomer Johannes Kepler for an Austrian nobleman, Hans Hannibal Huetter von Huetterhofen. The document had been purchased in Russia in 1886 by the first director of the Lick Observatory and had lain forgotten for a century.
Present-day astrologers always drag out poor Kepler in support of their bogus craft. See, they say, even such an eminent scientist as Kepler was a believer.
Kepler practiced astrology only as a matter of financial necessity. His heart certainly wasn’t in it. He wrote: “A mind accustomed to mathematical deduction, when confronted with the faulty foundations [of astrology], resists a long, long time, like an obstinate mule, until compelled by beating and curses to put its foot into that dirty puddle.”
Kepler’s distrust of the “dirty puddle” hasn’t rubbed off on Americans. Polls show that half of Americans are open to astrological influences in their lives. Most newspapers and magazines offer horoscopes. Even those people who say “Oh, I just do it for fun” will sometimes admit that “Well, maybe there’s something to it.”
“After all,” they say, “science doesn’t know everything. Maybe, just maybe, the positions of the planets and stars do affect out lives. Haven’t people believed it for thousands of years? Didn’t Kepler believe it? I may not be able to prove it is true, but neither can science prove it is wrong.”
And, of course, they are right. Science can’t prove that astrology is wrong because the whole system is so slippery and vague that it’s impossible to get a grip on it. That’s what Kepler meant by “dirty puddle.” A typical horoscope is loose enough to let almost anyone see themselves in it. Whatever Kepler gave Hans Hannibal Huetter von Huetterhofen, we can be confident that his customer went away thinking he got his money’s worth.
It was the genius of the British philosopher Karl Popper to realize that nothing in science can ever be proved absolutely true. Just because something “works,” doesn’t mean it’s right. But what we can sometimes do with confidence is show that a scientific idea is wrong.
As Popper said, good science is “falsifiable.” An idea that offers ample opportunities for falsification, yet resists refutation, is to be valued highly. An idea that can’t be proved wrong is simply not science.
When Kepler discovered what we now call Kepler’s Laws of Planetary Motion, he found precise mathematical formulae that describe the motions of the planets and their moons to a high degree of precision. A single unambiguous exception to the laws would show that something is amiss. Four hundred years later we have not found an exception.
But when Kepler cast horoscopes, it was a “well, maybe” sort of thing.
Since the 1950s, many scientific studies have attempted to assess the accuracy of astrological predictions, usually by asking astrologers to match horoscopes to people in blind tests. The results have been overwhelmingly negative. In spite of hundreds of person-years of research, not one shred of reliable evidence has emerged to show that astrology is anything but bunk.
Do astrologers therefore concede that their horoscopes are a swindle? Not on your life. The system is much too elastic for that.
Psychologist Ivan Kelly of the University of Saskatchewan lists a number of ways astrologers get around the scientific critique of their craft:
- Ignore bad news. Kelly quotes several astrologers who take this tack, including John Anthony West in his The Case for Astrology: “Since the aim of this book is to present the positive evidence, intimate details of the bulk of the negative evidence do not concern us.” This has been the dominant response of the astrological community.
- Knock science. Astrologer Robert Hand writes: “I don’t think that science is yet capable of dealing with the full complexity of the symbolic language as employed by astrologers.”
- Move the goal posts. There are so many different ways of doing astrology that if a scientific study debunks one method, the astrologer simply invokes another.
- Invoke negatives. The phenomena of astrology are subtle and elusive and require more creative ways of investigating them than have yet been mustered, say astrologers. Kelly quotes a professional astrologer who admits the absence of scientific evidence for astrology — so far: “I am personally still convinced that, given more sensitive and imaginative tests, confirmation of the reality of sun-sign typologies, and the signs generally, will be obtained.”
- Blame faulty methods. Astrologer West, for example, says that scientific criticism of astrology is irrelevant because astrology is a “system of magic,” where magic is “the attempt to master fundamental laws of resonance that have produced the cosmos.”
In other words, the practice of astrology is so slippery and ambiguous that it cannot be falsified. That is why it continues to flourish in spite of failing every scientific test. And that is why astrology is different than science.
