On Saturday, 16 November 2024, I presented a 30-minute talk on “Astrology and Science” at Conway Hall in London as part of “Divination Day”, organised by the London Fortean Society (subtitle: Astrology, Tarot, Tomorrow and Us”). It was quite a strange experience as I was the only speaker of the day who actually offered a skeptical perspective on divination. It was clearly not what the audience wanted to hear. Maybe readers of the Skeptic will appreciate it more – so here it is.
In preparing my short talk, I made a lot of use of the volume “Understanding Astrology: A critical review of a thousand empirical studies 1900-2020” by Geoffrey Dean, Arthur Mather, David Nias, and Rudolf Smit, published in 2022 by AinO Publications in Amsterdam. This massive volume (948 pages) is a labour of love by four of the world’s leading experts on empirical tests of astrology that has taken many decades to compile. Although the book can be purchased directly from the publisher, this invaluable resource can also be downloaded absolutely free. This book really does tell you everything you ever wanted to know about astrology.
As for my talk, I started in the traditional manner with a definition. Astrology is defined by the Cambridge online dictionary as follows: “the study of the movements and positions of the sun, moon, planets, and stars in the belief that they affect the character and lives of people”. I pointed out that astrology is also used, amongst other things, in attempts to predict major terrestrial events such as wars, natural disasters, and famines.
By way of preliminary comments, I made a few points that in and of themselves ought to prompt a certain degree of caution in assessing the bold claims of astrologers. For example, although my talk dealt mainly with Western astrology, there are several other versions of astrology, such as Chinese, Hindu, and more – and they all contradict each other. Clearly, they cannot all be valid (and, as it turns out, none of them are).
While no one really knows what the origins of astrology are, one thing we can be absolutely certain of is that, contrary to the claims of many astrologers, it is not based upon careful observation and empirical analysis. For one thing, there are no known records of any such exercise. For another, “there are far too many combinations [of factors] in astrology for our unaided abilities to make sense of” (Dean et al, 2022, p. 70). It is also worth noting that, according to physics, there is no known mechanism whereby astrology could work.
Professional astrologers are often very dismissive of star sign (or sun sign) astrology in spite of the fact that many of them are handsomely rewarded for writing star sign columns for newspapers, magazines, and online sites.
They insist that the power of astrology can only be revealed by examination of “the real thing”; that is, the casting of a full horoscope by a professional astrologer based on exact birth details which is then interpreted in a face-to-face consultation between astrologer and client. The truth is that, when properly tested, the “real thing” turns out to have exactly the same level of validity as star sign astrology; that is to say, none whatsoever.
I also wanted to deal up-front with a couple of pseudo-controversies that skeptics often delightedly (and, in my view, misguidedly) point to as allegedly killer blows for astrology. The first of these is the phenomenon of precession. Because the axis of the Earth’s rotation has a slight wobble, the stars overhead do not appear to be in the same position as they were 2,000 years when Western astrology originated. In fact, the constellations that the signs of the zodiac were named after have all moved by roughly one sign. Despite this, Western astrology today is much the same as it was 2,000 years ago. How can this be when, for example, the Sun was actually in Taurus when people who think they are Geminis were born?
Furthermore, it is often claimed that there are, in fact, 13 signs of the zodiac, not 12. The Babylonians knew all about Ophiuchus, the so-called 13th sign, but simply chose to ignore it as they had a bit of a thing about the number 12. The point is that neither precession nor the “13th sign” are recent discoveries.
Astronomers did not suddenly look at the night sky and declare, “Oh my goodness, there’s a constellation that we missed!”. Astrologers have long known about both of these astronomical phenomena but they insist that they are totally irrelevant when it comes to the validity of astrology. For one thing, constellations and astrological signs are not the same thing, despite having the same names. More importantly, astrologers insist, they know astrology is valid – because it works! But does it?
When I was running my anomalistic psychology module at Goldsmiths I used to set the following essay title as a tutorial topic: Does astrology work? The best essays were those which essentially answered, “Yes and no”. In what sense does astrology work? Dean (2016, p. 45) summarises the case for astrology:
Astrology is among the most enduring of human beliefs and has undisputed historical importance. A warm and sympathetic astrologer can provide wisdom and therapy by conversation with great commitment that in today’s society can be hard to find. To many people astrology is a wonderful thing, a complex and beautiful construct that draws their attention to the heavens, making them feel they are an important part of the universe.
But when it comes to the question of whether or not astrology works in the sense of having any scientific validity, the answer is a resounding, “No”! Sometimes astrologers claim that science is simply incapable of testing astrology – and yet you can guarantee they will enthusiastically embrace any empirical findings that appear, at first sight, to offer support for astrology.
This is nicely illustrated by the reaction of astrologers to the publication in 1978 of the results of a study by Mayo, White, and Eysenck. At the time, Hans J. Eysenck was the most influential living British psychologist (albeit that his reputation has taken quite a battering since then). Extraversion scores, assessed using the Eysenck Personality Inventory, were collected from a large sample of adults (n = 2324) and plotted against astrological sign. According to traditional Western astrology, the so-called fire and air signs (Aries, Leo, and Sagittarius; and Gemini, Libra, and Aquarius, respectively) should be more extravert than the earth (Taurus, Virgo, and Capricorn) and water signs (Cancer, Scorpio, and Pisces) – and this is precisely what was found. The results were hailed by astrologers as “possibly the most important development for astrology in this century”.
Their reaction changed somewhat when it was subsequently realised that this pattern of results was due to an artefact known as self-attribution bias. If astrology really worked, it should work whether or not the individuals assessed know anything about their own star sign. In fact, this pattern of results was only found for people familiar with their own star sign. It appears that, whether one believes in astrology or not, most of us know enough about the supposed astrological characteristics of our star sign for it to have enough influence on the way that we complete a personality questionnaire to artefactually produce the reported results.
As indicated by the subtitle of Dean et al’s volume, the predictions of astrology have now been put to the empirical test (at least) a thousand times. The results overwhelmingly fail to support the validity of astrology. When occasional apparently positive significant results in support of astrology are reported, they are invariably found to be due to such factors as inappropriate statistical analysis, inadequate sample sizes, and a range of other artefacts as meticulously detailed by Dean and colleagues.
By far the longest chapter in Understanding Astrology is Chapter 7, which provides critical analysis of a plethora of individual studies of astrology’s claims. Helpfully, Chapter 8 provides overviews of tests divided up into a number of different categories. With respect to tests of signs, the conclusion is clear: “signs (not just sun signs) [are] the most tested and most disconfirmed idea in astrology. In short, no factor involving signs can have any practical effect beyond that due to expectation and role-playing” (Dean et al, p. 772).
When it comes to tests of astrologers themselves, the picture is equally bleak. For one thing, the degree of agreement between astrologers assessing the same chart is abysmally low. Tests relating to geophysical factors, time twins, predictions, horary astrology, mind-related factors, divination, and wrong charts fare no better. The overall conclusion is inescapable. Despite a huge amount of time, effort, and resources having been directed at testing astrology, there is no evidence whatsoever that it has any validity.
In my talk, I also considered the issue of the scientific status of astrology. Up until fairly recently, astrologers were keen to claim that astrology was a true science as shown by a plethora of quotations on page 86 of Understanding Astrology. Indeed, some went so far as to describe it as “the oldest science in existence” and “the most exact of all the exact sciences”. More recently, many astrologers have adopted a negative attitude towards science, no doubt as a result of the accumulation of consistently negative findings from properly conducted scientific tests of astrology.
When it comes to discriminating between science and pseudoscience, a number of commentators have proposed lists of the features that typically characterise pseudoscience. My favourite such list was that proposed by the late Scott Lilienfeld (2005):
- A tendency to invoke ad hoc hypotheses, which can be thought of as “escape hatches” or loopholes, as a means of immunising claims from falsification
- An absence of self-correction and an accompanying intellectual stagnation
- An emphasis on confirmation rather than refutation
- A tendency to place the burden of proof on skeptics, not proponents, of claims
- Excessive reliance on anecdotal and testimonial evidence to substantiate claims
- Evasion of the scrutiny afforded by peer review
- Absence of “connectivity”, that is, a failure to build on existing scientific knowledge
- Use of impressive-sounding jargon whose primary purpose is to lend claims a façade of scientific respectability
- An absence of boundary conditions, that is, a failure to specify the settings under which claims do not hold.
When astrology is assessed in terms of these features, I think any reasonable person would agree that astrology is indeed the Queen of Pseudosciences.
If astrology has no scientific validity whatsoever, the obvious question raised is why do so many people believe in it? Dean et al do an excellent job of addressing this question in Chapter 9 on Artifacts. I only had time to address this issue briefly (my whole talk was only 30 minutes long after all!) in terms of such factors as the Barnum effect (AKA Forer effect), cold reading (intentional and unintentional), subjective validation, making the chart fit the client, making the client fit the chart, selective memory, self-fulfilling prophecies, and the use of (generally) positive readings.
I finished with my favourite astrology cartoon from Punch. A bemused man is staring at the TV as a newscaster reports that, “The practice of astrology took a major step towards achieving credibility today when, as predicted, everyone born under the sign of Scorpio was run over by an egg lorry”. I got the distinct impression that my audience did not appreciate the cartoon as much as I did.
References
- Dean, G. A. (2016). Does astrology need to be true? A 30-year update. Skeptical Inquirer, 40(4), 38-45.
- Dean, G., Mather, A., Nias, D., & Smit, R. (2022). Understanding Astrology: A critical review of a thousand empirical studies 1900-2020. Amsterdam: AinO Publishers.
- Mayo, J., White, O., & Eysenck, H. J. (1978). An empirical study of the relation between astrological factors and personality. Journal of Social Psychology, 105, 229-236.
