Astrology

"The good Christian should beware of [astrologers], and all those who make empty prophecies. The danger already exists that the [astrologers] have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell."
St. Augustine (354-430) DeGenesi ad Litteram, Book II, xviii, 37

History of Astrology

Astrology has existed, in some form or other, for over 3,000 years. More than a few of the greater minds of civilization, Western or Eastern, have taken it seriously. For many centuries it was barely distinguished from what we now call "astronomy"; in fact, astronomy was developed in part to allow the making of astrological predictions. The great astronomer Kepler was also an adherent of astrology, writing that "one should only disbelieve in idiocy and blasphemy; from the astrologers a useful and healthy wisdom can emerge." Even IsaacNewton showed some sympathy with astrology, though he hid it out of fear of religious persecution.

And, much as our presidents now have economic advisers, monarchs and popes often used to employ an astrologer full-time to help guide them in the making of important decisions; the office of 'Astrologer to the Royal Court' was thus a potentially powerful position. The present version of astrology, developed by the ancient Greeks around 400 B.C., was codified by Ptolemy in the second century A.D. in his Tetrabiblios. So astrology's basic text has remained pretty much unchanged during the last 18 centuries.

See also RESOURCE GUIDE TO THE HISTORY OF ASTROLOGY

Basic Principles

Look at the sky on a clear, dark night. The impression one may get is of many points of light pasted on the inner surface of a great hollow sphere centered on Earth. As the world turns, this celestial sphere appears to turn daily around Earth's own axis of rotation. The stars seem to rise and set, but there are many fixed constellations in which the stars relative positions remain constant. The planets Mercury, Venus, Mars, Jupiter, and Saturn, all visible to the unaided eye, seem to move with respect to the fixed stellar background. Their movements all appear to be in roughly the same plane as that of Earth's motion around the Sun, a region that forms a belt, centered on the Sun's path, around the celestial sphere. According to astrology, this celestial belt is divided into twelve equal regions, represented by the twelve signs of the Zodiac. In order from East to West they are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. (It takes about a month for the Sun to move through each region.) During the calendar year, each of the planets and the Sun are in one or another of these regions. For example, on July 12, the Sun is in Cancer; on May 11, the Sun is in Taurus; on February 23, in Pisces, etc. This gives us a crude coordinate system for locating the planets and Sun with respect to the stellar background; a bit more work is required to figure out how the planets and Sun are oriented in the Zodiac relative to points on Earth from which they may be observed. From Earth, the celestial sphere seems to rotate about Earth's axis; this is why heavenly bodies appear to rise (in the East) and set (in the West), gradually moving across the sky. The 12 astrological houses are simply stationary regions of the sky, fixed with respect to the horizon, that can be used to locate planets and signs relative to the Earth's vantage point. To determine a person's natal horoscope one maps the locations of signs and planets in each of the twelve houses not only at the time of that person's birth, but also from the vantage point of that person's birthplace. It is a rather elaborate and somewhat arbitrary coordinate system for locating some heavenly bodies relative to a person's birthplace and date. So far, so good.

Astrology's main interest derives from its assertion that certain physical and psychological characteristics are associated with each of the signs and planets and that each house governs some aspect of a person's life. So, for example, the first house is alleged to control temperament and personality. If Mars, the Roman god of war, is in that house, the individual is likely to be aggressive; if Aries, the sign controlled by Mars, is also in that first house, astrology would predict an extremely aggressive temperament. Of course, scores of other factors may operate in a natal horoscope and hence astrology is not committed to predicting that the individual with Mars and Aries in the first house is bound to be, say, an axe-murderer; if in addition the tenth house, which controls career, were inhabited by Neptune, a water (or wishy-washy) planet, a planet therefore associated with indecisiveness, that aggressive person might never be able to make up his mind whom to attack. Interpreting a chart and weighing all of the simultaneous influences is therefore a complex matter indeed. Nevertheless, it is sufficiently well-ordered by rules of interpretation that much of the task can be done efficiently by a suitably programmed microcomputer. As the world turns, so the home front soap opera evolves.

Notice that what we have said so far about astrology means that the Daily Horoscope columns in newspapers are, by astrology's own lights, bound to be misleading at best. All they deal with are Sun signs, but many other influences are present in each individual's chart, and all of these must be thrown into the mix before one can hope for reasonably accurate predictions. If we're to be fair, we can't judge astrology by its worst practitioners.

Is Astrology Pseudoscience?

Let's look at some of the criticisms that have actually been made of astrology. Keep in mind that we are concerned with the question, What is the difference between science and pseudoscience? We must understand that question in the right way if we are to find the kind of answer we want, namely, some principle that will help us decide when not to bother investigating. Most of us share a strong conviction that not every explanation, hypothesis, or theory is worth attention in a science course. If I tell you that my wrist watch is run by invisible gremlins, you're not likely to apply for a grant to check the hypothesis. This is different from the situation we're in when someone offers an explanation, we don't know whether it's true, and it turns out on investigation to be false. Many works of genius have turned out to be wrong in the end. No one wants to say that Newton was a pseudoscientist simply because Newtonian mechanics, his theory of gravity, was wrong. So our primary concern here is with a gatekeeper that can tell us what is investigation-worthy and what should be locked out. Does astrology qualify for the race?

Many scientists and skeptics have asserted that it does not qualify. We'll look at four of the many reasons that have been offered.

I mentioned Mars, the god of war, in my description of astrology's basics. When the ancients examined the planet Mars (no telescopes then), it appeared red. This reminded them of blood and war, so they supposed that it was the home of the deity in their polytheistic religion who was in charge of war. The planet was actually named after the deity and gained its astrological association with aggressiveness in this way. So unless you worship Mars, Zeus, Mercury, Neptune, and the other gods in the Greek or Roman pantheon, you've little reason to be sympathetic to astrology. If, like most people nowadays, you regard ancient Greek and Roman polytheism as at best interesting mythology, then you may instead be persuaded by the first criticism of astrology:

Astrology did originate in this way, but so did astronomy, with which it was closely allied for many centuries; and the same is true of chemistry, with its origins in alchemy (the attempt to transmute lead into gold by discovering the fundamental animating principle of matter); and of modern medicine and biology. They are not on those grounds pseudoscience. Nor should this surprise us. Ancient religions were the first systematic attempts to make sense of the order and disorder in the world. From where else could modern science have developed? Perhaps, for all this criticism says, astrology has transcended its magical origins.

The first criticism focused on a narrow portion of astrology's history, and it failed. Taking into account a larger portion of its history may yield a better criticism, so let's take all of astrology's history into account. I noted that astrology's basic text, Ptolemy's Tetrabiblios, was about 1,800 years old. Suppose you enrolled in a physics or biology course in and found that the instructor had assigned an 1,800 year-old text. You would, I think, look for another instructor. Science is marked by rapid change and progress. The rate of change is now so great that scientists are forced to subsubsubspecialize, and even then they can barely keep up with the books and journals directly pertinent to their restricted domain. A rough, simple rule-of-thumb measure of progress in any specialty in science is the number of linear feet of library shelf space the specialty's published output takes up annually, plotted over the specialty's lifetime. For any established modern branch of science, the slope of the resulting curve will be pretty steep over the last decade or so. Astrology, however, does rather poorly in this test, having been stuck at about two inches for the last eighteen centuries or so.

This criticism of astrology is not factual. In the first place, astrology has not been entirely stagnant. When Uranus, Neptune, and Pluto were discovered - only after the invention of the telescope - astrologers modified their schemes to take these planets into account. And during the past forty years, many new systems of astrology have been developed, many more complex than their predecessors. In the second place, why would great change or progress be expected if the theory is correct to begin with, or well along the right track? The principles governing chemical interactions have been known for some years, and while great progress has been made in their application, the basic principles haven't changed much. Does that make chemistry a pseudoscience? Of course not. Suppose that in some specialty in science we actually discovered the relevant truths and were able to explain them: further change would be regress, not progress. So this second criticism of astrology would imply that the most successful science was pseudoscience, exactly the opposite of the result we want.

Generally, historically based criticisms will tell us little that settles the scientific status of a theory. So let's take a closer look at the theory itself - never mind when or where it grew up, or what it's been doing since then.

According to astrology, distant physical objects exert a profound influence on you at and after the moment of your birth. Of the four known forces in nature - electromagnetism, strong nuclear, weak nuclear, and gravity - only gravity could have such influence over such long distances. Could the force of gravity carry astrological influences? Pretty clearly not. There were many objects close by when you were born that exerted comparable gravitational force on your infant body, but about which astrology is silent; for example, there was your mother. So it can't be gravitational force that carries astrological influences, which means that none of the known forces of nature is responsible.

This is wrong on two counts. First, since organisms can be extremely sensitive to very weak forces, the suggestion cannot be ruled out as physically impossible. Homing pigeons, for example, are thought to navigate by detecting small point-to-point variations in Earth's already rather weak magnetic field; the large literature on biomagnetism contains many other examples. Second, many scientific claims are made in the absence of any known underlying physical mechanism. When the theory of continental drift was first proposed, drift could not be explained by any known mechanism; plate tectonics came later, after the view of Earth as a rigid ball of rock was replaced with the more accurate picture of a spheroid of highly viscous fluid on which the continents float. The term "gene," for the unit of heredity, was coined and a fair portion of its theory proposed well before the advent of modern molecular biology. And few doubt that there is a strong causal connection between smoking and lung cancer, but no one knows the precise causal mechanism involved - because no one knows the details of carcinogenesis. The fundamental error in this criticism of astrology is to look at it only in terms of a part of science, the part that explains by means of laws and theories. But there's another part: discovery of new phenomena that have yet to be explained.

The last criticism of astrology that I want to consider is the most common. It has a number of different motivations, but all aim to show that astrology is not testable.

I have heard critics say that astrology is not testable because it is not based on observation. Where, the critics ask, are the observations of human behavior under planetary influence that would be needed to sustain astrological theory? And then there is the language of astrology, which, being largely the language of human thought and emotion, is shot through with vagueness. Just think of all the ways in which feelings may be manifested and how easy it is to make a mistake about someone's emotional state or thoughts. Since the predictions of astrology use such language, we're unable to tell what they say, and without a well-defined target, one can't distinguish a hit from a miss. Finally, there is the behavior of astrologers, who are forever excusing their missed predictions. If you've ever seen a sharp reporter take on a slippery astrologer, you know how the conversation goes. Every challenge is met with some new, previously ignored factor from the progression of the person's horoscope, and the result is that one never gets a settled, definite prediction about what the person's life will hold.

This is one of the most common charges against astrology, and it is also one of the most ill-conceived. In a perfectly reasonable sense of the phrase, astrology is 'based on observation', namely, on observation of the relative positions of certain heavenly bodies (and remember that telescopic observations resulted in revision of astrology). "But," you say, "it's not based on observation in the right way!" Good point - or it would be if you could tell us what, in general, the right way is. (As we'll see in a later discussion, the link between theory and observation is more indirect, complex, and circuitous than many critics of pseudoscience have thought.) It is true that many of the terms of astrology are somewhat vague, but we're accustomed to working with vague terms and seem to do quite well with them. Many of astrology's vague terms do indeed come from our language of character description. "Angry" and "aggressive" are vague terms, but we can apply them quite reliably. Nor is astrology unique in being infected with vagueness; even biology, clearly a science, has trouble with "living thing" - are viruses to be included or not? Maybe astrology is vaguer than biology, but that may simply reflect its subject matter: predictions of human feeling and action. Can any missed prediction be excused? Not if astrologers respond honestly to the questions put to them; and some of them do: they sometimes make fairly specific predictions about an individual's character and life. Besides, what's at issue here is not the moral character of astrologers. Any theory can be misused, and the fact that astrology may sometimes be misused by some astrologers is irrelevant to that theory's scientific status. We might as well condemn Newtonian mechanics as pseudoscience because it has been used to guide weapons of war. The main problem with this criterion, though, is that it sets standards that are far too low for scientific status. Although it is possible to concoct hypotheses that are in no conceivable way testable, it requires something of an imaginative stretch (see the discussion of Ruse's criticisms in Scientific Creationism in the Courts, for example). Almost any hypothesis or theory that is someone is likely to think of will be open to some sort of conceivable experimental test, will be tied in some way to observation. Certainly, astrology passes this test with flying colors since many of its predictions have actually been shown to be false.

Other charges have been made against astrology to show that it's pseudoscientific, but this is a fair sample. And none of the principles in this sample show that astrology is a pseudoscience.

None of this is to say that astrology is a correct theory of human personality and behavior. It may be a tissue of falsehoods. In fact, statistical studies have turned up plenty of evidence against astrology, and no good evidence for it. So it is surely wrong. But that wasn't our question, and it's not the main charge made against astrology by many of its critics. They claim that it doesn't qualify for the race at all.

In the case of astrology, we may not care much whether it is pseudoscience or scientific-but-false. After all, the view, despite its popularity, is pretty clearly bunk. But we can't always afford to be indifferent to such matters of principle, especially when we are confronting a controversial view or are entering a gray area between clear investigation-worthiness and clear crackpottedness. The lesson of astrology may be important not for what it teaches us about astrology, but as a warning that those matters of principle are less straightforward than they may have seemed.

Additional Sources

2000 David F. Austin

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