Astrology is an ancient form of divination where people's lives and personalities are predicted on the basis of the juxtaposition of the sun and moon against the backdrop of the stars1 stemming from a time when we didn't understand the world2. Of particular importance for a person's whole life is their month of birth. Practices based on astrology include the production of horoscopes, prediction of imminent or medium-term events in people's lives. Belief in astrology has been in long-term decline in the developed world and it is opposed by most established organized religions3, but it is still a popular feature of many new religious movements4,5 and astrological charts can still be found in almost every daily newspaper in the form of horoscopes1. One academic writes that "there can be few Western Europeans who do not know their zodiac sign"6. It is part of the underlying theory of the New Age7,8, and is very popular in India in particular, where it is institutionalized.
Astrological predictions have been tested scientifically and have been comprehensively found to be mistaken in both theoretical underpinning and practical application9,10,11. For example, David Voas looked at over ten million married couples and found absolutely no statistical effects relating to marriages between people of particular zodiac signs12. And Chinese astrology has a long history, but, they group the stars into completely different constellations and give prominence to the lunar mansions ("a 28-sign lunar zodiac")1. So it is clear that astrology isn't based on any particular sound theory. Over the last 2000 years, the precession of the equinoxes has meant that each equinox and solstice point has moved around 30 degrees; an Aquarius today genuinely isn't the same sign as an Aquarius from history. Also, the dots that make up constellations are mostly stars, but many points are extremely distant galaxies, and the entire ensemble slowly moves and shifts over time, making most traditional methods of astrology useless13. Lack of knowledge of basic astronomy has made a mockery of astrology. Also poor is their biology: we now know that as our genes are combined at point of conception, the emphasis on the month of birth (a person's "sign") is never going to be a good predictor of personality. Especially if you don't ask subjects how long they were in the womb for. The Forer Effect explains why most people readily accept that astrological descriptions are accurate - randomly assigned profiles are rated just as highly14,15,16. Astrological predictions of statistical likelihood of car crashes, divorces, etc, based on the month of birth nearly all fall foul of a simple statistical glitch - the Age Incidence Error17. Despite these problems, many continue to believe in astrology and horoscopes because general knowledge of statistical methods and general knowledge of thinking errors such as the Forer Effect is poor. Also, it is popular because it is entertaining18.
Ancient humans perceived patterns in the complicated movements of the stars and visible bodies of the solar system. They derived from them an idea that life on Earth is controlled by an unseen mechanism of the universe. This was the era of humanity in which animism reigned: everything had a spirit that controlled it, from the weather to personal life events..
Everyone is familiar with the 12 signs of the Zodiac (even if they can't list them!): Aries the Ram, Taurus the Bull, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces. The oldest preserved zodiac dates from 3000BCE when the Sumerians in Mesopotamia developed their Zodiac based on twelve heavenly bodies they could see, such as planets. The Babylonians, with their numbering system of 60, found the number 12 to be practical and useful for calendars and times. The author of "Science: A Four Thousand Year History", Patricia Fara, says "the Babylonians split the heavens into twelve equal sections, one for each lunar month and carrying the name of a prominent constellation. Translated into Latin, these now exist as the twelve signs of the zodiac"19. This idea was passed on from culture to culture:
“The notion of the zodiac is very ancient, with roots in the early cultures of Mesopotamia. The first 12-sign zodiacs were named after the gods of these cultures. The Greeks adopted astrology from the Babylonians, and the Romans, in turn, adopted astrology from the Greeks. These peoples renamed the signs of the Mesopotamian zodiac in terms of their own mythologies, which is why the familiar zodiac of the contemporary West bears names from Mediterranean mythology.”
Astrology is used for personal fortune-telling, predicting events up the international scale and as a self-help exercise1 (in the same way as tarot: using random symbols to tease out self-interpretation). The actual methods used are quite varied, with a mix of traditional and individual techniques being used to analyse what the position of the planets means for you personally.
“Outside the West, the two most significant schools of astrology are Chinese astrology and Vedic [Hindu] astrology [which is] is ultimately rooted in Mesopotamian astrology [...]. The influences of the planets are determined according to their placement in the 12 signs of the zodiac [but] uses the 'sidereal' or 'fixed' zodiac in contrast to the 'tropical' or 'moving' zodiac favoured by Western astrologers. [...]
Chinese [astrologers] group the stars into quite different constellations. Also, the Chinese traditionally gave primary importance to the Moon's placement in the daily lunar mansions (a kind of 28-sign lunar zodiac). [Unlike Western astrologers who use tables] traditional Chinese astrologers maintain a continual watch of the heavens.”
As a result of its usefulness, the number 12 has also found itself the center of many spiritual, magical and superstitions schemes.
"There are probably more than 10,000 professional astrologers in the English-speaking world, serving more than 20 million clients" writes James R. Lewis1. It is a popular feature of many new religious movements20, and some of those movements are made more popular because they indulge in astrological activities1. Astrological charts can be found in almost every daily newspaper in the form of horoscopes1 and scholar of religion Steve Bruce notes that "there can be few Western Europeans who do not know their zodiac sign"21.
Despite the popular appeal, most people are conscious that it does not constitute a sensible approach to the world. Steve Bruce points out that "a survey of implicit religion in Leeds conducted in 1992 showed 75 per cent of people saying that they looked at their horoscopes but only 19 per cent saying that they 'believed in it'. [...] It seems to be the case that we are happy with astrology as a 'bit of fun', a 'laugh', but regard as deviant those who take it too seriously"21. He continues:
“Consider the ways in which people show an interest in astrology. A very small number of people make their livings as astrologers. A larger number strongly believe that the solar system is the symbol of a living energy pattern and that its arrangement tells us something useful about human personality and the course of events. They will use birth maps and birth signs as a guide to interpreting the behaviour of themselves and others, and will consider the lie of the planets before making major decisions. This may be done with more or less seriousness and consistency. Beyond them, we have those whose involvement is restricted to reading horoscopes with no conviction that they are useful but with the general supposition that it cannot do any harm. In this circle there are a very large number of people. The fourth best-selling book of 1993, behind three novels, was 1994 Horoscopes, which sold 480,000 copies in the UK, which is about one for every 100 adults.”
"Religion in the Modern World: From Cathedrals to Cults" by Steve Bruce (1996)21
The record of astrological predictions is very poor. Hundreds of properly conducted controlled tests in the West have all found no basis for astrology10. In the largest study ever undertaken of horoscopes, David Voas looked at over ten million married couples:
“Even the smallest tendency for Virgos to fancy Capricorns or for Libras to like Leos would be apparent in the statistics. If only one pair in a thousand is influenced by the stars, we would see ten thousand more couples than expected with certain combinations of signs. In fact, the numbers are just what we'd predict based on chance.”
Prof. David Voas (2008)12
People's astrological signs do not predict success in marriage. But this complete lack of correlation does beg one more question: If people believe in astrology, it seems at first that a certain effect should be apparent. If all Virgos thought they had a better chance with a Taurus and married accordingly, it should show up. How come this sociological effect is not even apparent in the statistics? The reason is that horoscope advice is random. With so many columns giving so many contradictory opinions (as pointed out by astronomer Carl Sagan22), choices made by them are as good as random choices. So not only are the predictions random in nature, leading to random choices that people merely think are meaningful, but, the results of unions are completely unrelated to astrological signs.
“Predictions do not carry any controls. For example B.V. Raman (1912-1998), publisher-editor of The Astrological Magazine, wrote that 'when Saturn was in Aries in 1939 England had to declare war against Germany' (note the fatalism) in a work intended 'to present a case for astrology'23. However, this reasoning fails to notice that Saturn was also in Aries in 1909 and 1968 when nothing much happened.”
Such methodical research has not been conducted in India where astrology is protected by the state, but some examples have been collected by critics. In India's elections in 1971 the vast majority of the predictions in The Astrological Magazine were that Ghandi would lose: instead a victory was gained 'with an overwhelming majority'. Exactly the same happened in 1980. Rao (2000, 113-122) catalogues many similar failings and notes that "no astrologer predicted Ghandi's assassination in 1984, and that the golden rule seems to be 'predict only those things which please the listener's ego' "24.
Indian astrologers claim that they can tell intelligence from reading a person's individual horoscope. This was put to the test. The Committee for the Eradication of Superstitions in 2008 obtained horoscopes for 100 bright school children, and, 100 mentally handicapped children. Astrological organisations and many individuals took part in the challenge of ascertaining intelligence from the horoscopes, and, needless to say, they all fared no better than if they made random guesses. The same occurred when they guessed ages.25
It is apparent that Voltaire - never a straightforward author - has somewhat exaggerated this story in order to make it more ridiculous, as part of his typical style. The point is that he made these criticisms in 1764, highlighting a long history of skepticism about astrology:
“One of the most famous mathematicians in Europe, named Stoffler, who flourished in the fifteenth and sixteenth centuries, and who long worked at the reform of the calendar, proposed at the Council of Constance, foretold a universal flood for the year 1524. This flood was to arrive in the month of February, and nothing is more plausible; for Saturn, Jupiter and Mars were then in conjunction in the sign of Pisces. All the peoples of Europe, Asia and Africa, who heard speak of the prediction, were dismayed. Everyone expected the flood, despite the rainbow. Several contemporary authors record that the inhabitants of the maritime provinces of Germany hastened to sell their lands dirt cheap to those who had most money, and who were not so credulous as they. Everyone armed himself with a boat as with an ark. A Toulouse doctor, named Auriol, had a great ark made for himself, his family and his friends; the same precautions were taken over a large part of Italy. At last the month of February arrived, and not a drop of water fell: never was a month more dry, and never were the astrologers more embarrassed. Nevertheless they were not discouraged, nor neglected among us; almost all princes continued to consult them.”
It is seemingly widespread that the production of horoscopes for newspapers is simply fraudulent. In one such newspaper, the 'new kid' in the office is frequently given the job of going through old horoscopes from the newspaper dating from a few decades ago, and simply updating the English used in them, and republishing them. The results are accepted by the public as credulously as always.27
In the West, astrology places utmost important on the month of your birth. Whether you are a Pisces and an Aquarius depends on what month you were born in, and, which sign you are strongly affects your entire personality, for your whole life. Hence, why astrological predictions are possible at all.
But there is a fundamental problem and a serious contradiction of science, and of common sense. Firstly, the science: a great deal of our personality (half or more) is fixed due to genetics. And the point at which it is fixed it as the point of conception, not at the point of birth - yet astrology is obsessed with the date of birth!
Clever people might point out that all this means is that all charts are already adjusted by nine months, to account for the difference. But many people are not carried for 9 months - I was born after 7 months, for example. So does that mean I should be bumping myself backwards a Sign or two on the astrologers' wheel? And why do they never ask subjects how long they were in the womb for? It seems that they have little understanding of the real factors that affect our personality. Little problems such as these may seem insignificant but they demolish the idea that astrology has any meaning - our characters are simply not predictable from the month of birth.
On a minor note, some of these logical difficulties are obvious enough to be spotted even by people who are, otherwise, themselves quite irrational:
“Genetics tells us that the basis of our personality traits is formed, not at birth, but at conception, when one of the millions of sperm cells from the father unites with a single egg from the mother. Yet, astrology fixes one's horoscope by the moment of birth.”
Why do some people come to conclude that astrological advice means anything? Social psychologists have been studying questions such as this for some time. The Forer effect is the seeing of a personality statement as "valid even though it could apply to anyone", and is named after the psychologist who famously demonstrated it16. In 1949, Bertram Forer conducted a personality test, and then gave all of his students exactly the same personality profile, which he constructed from random horoscopes. The students rated the accuracy of their profile at over 80% on average29! This was occasionally previously known as the Barnum effect after a popularist entertainer. Extensive studies have found that this effect applies well to horoscopes, other astrological readings, messages given from the dead by spiritualists, various cold reading tricks and other profiling endeavours30. It is often mistaken for being a product of magical or supernatural means.
For more, see: The Forer (or Barnum) Effect.
“To say astrology "works" does not mean that astrology is accurate in predicting human behavior or events to a degree significantly greater than mere chance. There are many satisfied customers who believe that their horoscope accurately describes them and that their astrologer has given them good advice. Such evidence does not prove astrology so much as it demonstrates the Forer effect and confirmation bias. Good astrologers give good advice, but that does not validate astrology. ... There have been several studies that have shown that people will use selective thinking to make any chart they are given fit their preconceived notions about themselves and their charts. Many of the claims made about signs and personalities are vague and would fit many people under many different signs. Even professional astrologers, most of whom have nothing but disdain for sun sign astrology, can´t pick out a correct horoscope reading at better than a chance rate. Yet, astrology continues to maintain its popularity, despite the fact that there is scarcely a shred of scientific evidence in its favor.”
The Skeptic's Dictionary (2015)
Sometimes, supporters of astrology cite some seemingly relevant statistical details in order to 'prove' that astrology does have meaning. When it comes to statistics based on your month of birth, however, beware! What looks like pertinent correlations are in fact just artefacts of the way we divide our lives into months and years.
“There are also surprisingly strong variations due to an effect called 'age incidence.' Take anything dependent on age and counted by calendar year, such as possessing a driver's licence, going to a nonjuvenile prison, or joining a senior football team, and Aquarians (born in January) will have had more time 'at risk' than Sagittarians (born in December). If the counting period is set up differently in the calendar year, such as July to June, the relevant signs are different.”
We on Earth once saw the stars as equidistant pin-pricks in the sky: we devised constellations based on the assumption that the stars lay flatly in relation to each other. But in reality, many constellations are comprised of points that are simply billions upon billions of light years apart from one another, but when we look at them from Earth, they look like they line up in sequence. Some of the points are stars and some are entire distant galaxies that look like single points of light to us. The constellations themselves are illusions, based on simplistic mistakes made millennium ago.
That's not the only problems. The individual dots in the constellations have moved over time, so that the original charts no longer make sense. Over the last 2000 years, the precession of the equinoxes has meant that each equinox and solstice point has moved around 30 degrees; an Aquarius today genuinely isn't the same sign as an Aquarius from history. This problem is not even a new discovery - Voltaire in 1764 wrote:
“The great misfortune of the astrologers is that the sky has changed since the rules of the art were established. The sun, which at the equinox was in Aries in the time of the Argonauts, is to-day in Taurus; and the astrologers, to the great ill-fortune of their art, to-day attribute to one house of the sun what belongs visibly to another.”
Yet the art of astronomy continues as boldly as it always has, being actually proud of its traditions, rather than embarrassed by historical astronomical mistakes. A third source of problems is that the Earth's orbit is not perfectly regular, and all kinds of slow changes gradually shift our view of the stars and the position that the sun and planets casts against them.
“Because stars move (and astronomers can measure their 'proper motion', as it is called, by recording the changes in their spectra caused by the Doppler effect... the constellations have changed in shape since they were first named and recorded. [...]
In astrology, Aries is the first sign of the zodiac and kicks off the zodiacal year when the Sun is said to enter it on, or around, 21 March. This is also the approximate date of the vernal equinox - the start of spring in the northern hemisphere and of autumn in the southern hemisphere - when the Sun did once indeed enter the constellation of Aries, which is why the vernal equinox is also called the first point of Aries. In fact, due to the precession of the equinoxes, the Sun now crosses the celestial equator in Pisces.
Similarly, although the autumnal equinox, which occurs on, or around 23 September, when the Sun crosses the celestial equator again six months later, is called the first point of Libra, the Sun is [now] actually in the constellation of Virgo on this date.”
Because this problem is so well known, many astrologers have come to disassociate their practice from the physical appearance of the stars, and simply divide the sky into sections arbitrarily (but using the same divisions geospatially). The result is complete theoretical confusion, inadvertently highlighting the fact that astrology is not based on any particular worthwhile theory.
Astrology in India is significantly different, and much more complex, than that in the West and than in China. Amulets, chants, colours and gems all interact with the planets to create a system of almost infinite possibility. Of course, this means almost any failed prediction can be explained by various factors, and, almost any set of signs can be moulded to match events. It has 'possibly more part- and full-time astrologers than in the rest of the world put together. [...] As for the general public, one finds almost universal belief in it' although academics and scientists in India can be found opposing astrology. In the West, belief in astrology is not tied to any changes in behaviour linked to astrological columns in newspapers. So, people read them, and some profess vague belief in them, but, they do not act on what they read. In India, people act on astrology. In 1963 the Crown Prince of Sikkim delayed his marriage by one year in order to await a 'better' astrological date. In the 1990s an educated young man had a horoscope cast by computer, and it predicted total failure in everything he did. He killed himself as a result33. While the effects of horoscopes might be a humorous farce (or a tragedy) for an individual, it also has effects on the national scale. When days arrive that are said to be positive for marriage, huge numbers of additional weddings can take place, putting pressure on facilities.25
Senior Indian astrologers can make extreme claims about their craft. In 2003 Raj Baldev in the Indian Express claimed that ancient Hindu astrology is so accurate and scientific that 'one million billionth of a second 'makes a lot of difference'. Skeptics might wonder at this, since it implies that the shadows cast on ancient sundials were routinely positioned to better accuracy than a hundred millionth of the diameter of an atom. Even at night.'
Although many scientists and academics oppose it, the law courts and government, along with the people, support it. In a case in 2011 involving false advertising came to the High Court in Mumbair. "It was dismissed by the court arguing that the [false advertising] act 'does not cover astrology and related sciences. Astrology is a trusted science and [has been] practiced for over 4000 years...' "34.
“Astrologers have a notion of a 'Great Year' made up of twelve 'months', each 2,160 years in duration and each represented by a star sign in the Sidereal Zodiac. It is supposed that Stonehenge was built at the start of the Age of Aries, that the start of Pisces was marked by the birth of Christ, and that we now stand at the beginnimng of the Age of Aquarius, a period, as Bloom puts it, of 'more fluid and spontaneous relationships', a time of new powers.”
"Religion in the Modern World: From Cathedrals to Cults" by Steve Bruce (1996)36
“We are passing out of 2,000 years of Piscean astrological influence into the influence of Aquarius, which will affect all aspects of our culture, as we move from Piscean structures of hierarchical devotion to more fluid and spontaneous relationships that dance to an Aquarian rhythm.”
It is now well recognized that astrology and associated practices are the result not only of lack of knowledge, but also of instinctive erroneous thinking.
“We all suffer from systematic thinking errors38,39 which fall into three main types: (1) internal cognitive errors; (2) errors of emotion40, perception and memory; and (3) social errors that result from the way we communicate ideas and the effects of traditions and dogmas. Some of the most common errors are the misperception of random events as evidence that backs up our beliefs, the habitual overlooking of contradictory data, our expectations and current beliefs actively changing our memories and our perceptions and using assumptions to fill-in unknown information. These occur naturally and subconsciously even when we are trying to be truthful and honest. Many of these errors arise because our brains are highly efficient (rather than accurate) and we are applying evolutionarily developed cognitive rules of thumb to the complexities of life41,42. We will fly into defensive and heated arguments at the mere suggestion that our memory is faulty, and yet memory is infamously unreliable and prone to subconscious inventions. They say "few things are more dangerous to critical thinking than to take perception and memory at face value"43.
We were never meant to be the cool, rational and logical computers that we pretend to be. Unfortunately, and we find it hard to admit this to ourselves, many of our beliefs are held because they're comforting or simple44. In an overwhelming world, simplicity lets us get a grip. Human thinking errors can lead individuals, or whole communities, to come to explain types of events and experiences in fantastical ways. Before we can guard comprehensively against such cumulative errors, we need to learn the ways in which our brains can misguide us - lack of knowledge of these sources of confusion lead many astray45.
Learning to think skeptically and carefully and to recognize that our very experiences and perceptions can be coloured by societal and subconscious factors should help us to maintain impartiality. Beliefs should not be taken lightly, and evidence should be cross-checked. This especially applies to "common-sense" facts that we learn from others by word of mouth and to traditional knowledge. Above all, however, our most important tool is knowing what types of cognitive errors we, as a species, are prone to making.”