The Problem of Testing Astrology

by Bob Marks

There are three questions which may be asked when devising a test of astrology:

1) Is there an "astrological force" that would make it possible for astrology to work? If the answer to this is no, then the game is over and we all go home.

2) Do any of the anecdotal rules or principles of astrology actually work? Yes, there are several differing versions, but the key question is still: Can they be tested?

3) Can astrologers personally pass tests for accuracy?

The first question is the main one. In Astrology in the Year Zero on page 144, there is a startling statement made by the skeptic researchers.

"Gauquelin's work was certainly the most rigorous of its time. But his planetary effects even though independently confirmed by us (emph. added), are too tiny to be of the slightest practical value."

The problem here is that this is like being just a little bit pregnant. "Practical value" indeed! Practical value is for engineers, not scientists. The existence of an astrological force, no matter how "tiny", must be explained. Where does this force come from? How extensive is it? Can it be accounted for by the present basic forces known by science, or do we have a whole new form of energy here?

In addition, the existence of an astrological force changes the nature of the two remaining questions about astrology. Do the present rules of astrology "work" at all? Well, if there is an astrological force, and if the present rules don't work, we can find new ones. In fact, we shall have to find rules so that we can know the extent of this astrological force.

Can astrologers come up with accurate statements about a person? If there is an astrological force but astrologers fail tests, that could merely be an indication that better training is needed.

The only way a skeptic could deny that astrology has any possibility of working is to maintain that there is no such thing as an astrological force. Period. End of discussion. The existence of one white crow is conclusive proof that all crows are not black. The skeptics have found that white crow, but they don't want to count it because it is too small and can't fly. But it is still a white crow, and that cannot be denied.

Bob Marks

(for more on Bob, see: www.bobmarksastrologer.com & www.astrologyresearchjournal.org

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For a response from Prof Suitbert Ertel to Bob Marks's comments, with links to substantial articles, click here

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Geoffrey Dean replies to astrologer Bob Marks

In his article Bob Marks assumes that the Gauquelin findings must be evidence for an astrological force, and that an astrological force is necessary for astrology to work. Both assumptions seem unwise. Start with his first assumption about the Gauquelin findings:

First, as Kenneth Irving pointed out in Correlation 13(1), if effects relevant to astrology seem to exist then scientific study is needed to determine their mechanism. Or as Marks says, such effects “must be explained”. However, this will generally require multidisciplinary scrutiny before we can be sure that the effects do not have ordinary causes, and in this case the necessary multi scrutiny has yet to occur.

Second, Marks confuses a tiny effect with a tiny effect size. The bending of light by gravity is a tiny effect, but the effect size is maximum --if we know the gravity we can exactly predict the bending. In contrast, the Gauquelin findings have a tiny effect size -- if we know planetary positions we cannot predict anything useful.

Third, tiny effect sizes can have a huge number of ordinary causes, most of them impractical to control even if known. And ordinary causes have repeatedly turned out to underlie the tiny effect sizes that in their day were claimed to be convincing evidence for astrology. An example of effect size similar to Gauquelin effect sizes is the influence of belief in astrology on the birth rate in Japanese and Chinese populations, and (with twice the effect size) on self-image in Western populations. The influence mimics astrology but is clearly non-astrological.

Fourth, multi scrutiny can take time, for example the findings of John Nelson stood for thirty years before they were overturned. But astrology is nothing special here -- the Cottingley fairies stood for sixty years before they crumbled, it took forty years for the Fox sisters to admit their spirit claims were a hoax, and forty years for Soal’s “watertight evidence” for psi to be revealed as fraudulent. Therefore sensible people will say that, as long as the effect size is tiny and lacks multi scrutiny, ordinary causes are more likely than astrological ones.

Marks’s second assumption, that an astrological force is necessary for astrology to work, seems unwise because there are non-astrological factors that explain why astrology seems to work. When these factors are controlled, astrology no longer seems to work, so there is nothing for an astrological force to explain. To paraphrase Marks, the only way an astrologer could claim that astrology works is to maintain that there is no such thing as a relevant non-astrological factor, which is obviously problematic. This does not deny the possibility that an astrological force may exist, but at present there is no convincing evidence that such a force needs to exist. For more on non-astrological factors see under Tests & Snags on www.astrology-and-science.com.

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Astrologer Bob Marks Replies to Geoffrey Dean

In his reply, Dr. Dean begins:

“In his article Bob Marks assumes that the Gauquelin findings must be evidence for an astrological force, and that an astrological force is necessary for astrology to work. Both assumptions seem unwise.”

Yes, of course it’s evidence, although not conclusive proof.

My article was a response to statements made by the researchers on page 144 of Astrology in the Year Zero. That statement was:

“Gauquelin’s work was certainly the most rigorous of its time. But his planetary effects, even though independently confirmed by us, are too tiny to be of the slightest practical value.”

Please note that there was no mention made of an effect that seems to work, or of any multidisciplinary investigations being needed to see if this effect could have other, more ordinary causes. I responded to the passage as it was written, and it simply states that there was an actual effect. I am glad that Dr. Dean has now clarified his position. Dr. Dean continues:

“First, as Kenneth Irving pointed out in Correlation 13(1), if effects relevant to astrology seem to exist then scientific study is needed to determine their mechanism. Or as Marks says, such effects ‘must be explained.’ However, this will generally require multidisciplinary scrutiny before we can be sure that the effects do not have ordinary causes, and in this case the necessary multi scrutiny has yet to occur.”

No argument from me here. I am in total agreement on this point.

“Second, Marks confuses tiny effect with tiny effect size. The bending of light by gravity is a tiny effect, but the effect size is maximum – if we know the gravity we can exactly predict the bending. In contrast, the Gauquelin findings have a tiny effect size – if we know planetary positions we cannot predict anything useful.”

Here I disagree.

1) Not Useful? We have a working hypothesis here. It is now possible to test Gauquelin’s results against another batch of data to see if the results are replicated. That’s what science is all about.

2) By “effect size”, Dr. Dean seems to mean that some sort of guarantee must be made regarding the reproducibility of results. But the example of light being bent by gravity is not the best analogy for this case. It’s comparing apples to oranges. First of all, Einstein’s General Theory of Relativity predicted the gravitational effect theoretically. This led to the famous test with the photograph of the eclipse that provided confirmation of GTR. Now suppose that the photograph were taken before Einstein had come up with any theory. Then we would have a situation more in line with the Gauquelin’s study. There would have been a result for which no theoretical basis existed. And the exact same objections Dr. Dean makes against Gauquelin would apply. There would have been all sorts of objections claiming that mistakes might have been made (perhaps the camera was faulty, etc.). Of course, someone would have claimed that the bending of the light might have been due to some “ordinary cause” that had nothing to due with gravity. Dr. Dean seems to think that only the first case (guaranteed reproducibility) is “real” science, but this is not the case. Historically, there have been many times where an effect has first been established as real, and a theoretical basis established later. Tectonic Plate theory for one. Newton’s Laws for another. Newton himself was quoted as saying that he was able to succeed because he “stood on the shoulders of giants.” The giants in question were Galileo and Kepler, who empirically discovered laws of motion.

Dr. Dean continues:

“Third, tiny effect sizes can have a huge number of ordinary causes, most of them impractical to control even if known.”

Yes, of course. But from the fact that there could be a “huge number of ordinary causes”, it does not follow that there actually are any at all. This is a matter that has to be examined individually, case by case.

One of the “ordinary causes” that Dr. Dean refers to has been mentioned elsewhere. It has been alleged that parental tampering with the birth data has affected results. There are three objections here:

1) There is no direct evidence that this has taken place. It is not enough to simply raise a point like this and expect it to be accepted. A defense lawyer who simply tells the jury that the witnesses against his or her client were lying would not win many cases. It has to be demonstrated beyond a reasonable doubt that they actually were lying. Perhaps if there were some sort of “smoking gun” here to support the assertion, something like an autobiography titled “Confessions of a French Midwife”, with quotes like: “Oui, I held back the birth of the baby until Jupiter was on the Midheaven!”, this objection against Gauquelin would have more weight.

2) In the 19th century, belief in astrology in the West was at a low point. Astrology didn’t start to be revived until the advent of the Theosophists late in the century. That makes it more difficult to believe that there would have been enough believers around to produce an effect large enough to change Gauquelin’s results.

3) The biggest objection to the parental tampering hypothesis is the fact that Gauquelin found effects for “malefic” planets and none for the “benefic” Sun. In the 19th century (indeed, even today) it was widely believed in astrological circles that the planets Mars and Saturn had malefic results. What parent in their right mind would put either of those rising or culminating in their child’s horoscope? And which would be preferred to be in a strong position, the benefic Sun or the inconstant Moon? No, if there were parental tampering, there would have been effects for the Sun, Venus, and Jupiter alone. However, this was not what Gauquelin found.

Dr. Dean’s fourth point is that “multi scrutiny can take time.” Agreed. But so what? It is time well spent.

Dr. Dean continues:

“Marks’ second assumption, that an astrological force is necessary for astrology to work, seems unwise because there are non-astrological factors that explain why astrology seems to work.”

But I was not taking about astrology seeming to work. I merely stated that if astrology were to work, there would have to be something that made this possible, e.g. an astrological force. The alternative would be that something could work for no apparent reason at all. Please note that I did not state that astrology did work. Rather I was proposing a hypothetical if-then situation.
Dr. Dean concludes:

“This does not deny the possibility that an astrological force may exist, but at present there is no convincing evidence that such a force needs to exist.”

We are in agreement here. And that is why I am doing statistical research. Two papers have already been published and are available on the internet at www.astrologyresearchjournal.org

A third paper is to be published shortly. It is always up to the one making the assertion to provide the evidence. Therefore, skeptics don’t have to disprove astrology. It is up to astrologers to prove their assertion that astrology works. This is a challenge that I accept.

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