Astrology is, most generally, the belief that human events hold a relationship with celestial patterns and phenomena. Its method of study and practice is subject to cultural variation, but in popular Western culture it manifests as a series of regular horoscopes, corresponding to a person's date of birth, which predict and explain aspects of one's personality and future life events. Over most of its history, it was practiced as a legitimate and respected science, and although it still carries itself as one, discrepancies with developments in physical sciences over the past few centuries has demoted its status to a superstition.

Description and Method


Documentation of celestial cycles is an essential practice of civilization, as it is a consistent basis for time and necessary for successful agriculture. It is believed that the development of astrology coincided with the deliberate archiving of these cycles. The earliest developments of solar calendars are unknown in their chronology, but primitive diagrams on cave walls suggest that lunar phases were being observed as early as 25000 years ago (Campion, 2008). Development of astrology continued to meet agricultural and time-regulating needs. Eventually the custom became of diving a circle into degrees, arcminutes, and arcseconds, which created a standard for precise measurements to be made of the positions of objects in the sky with respect to an earthbound observer. There is evidence to suggest that by 3000 B.C. most civilizations had taken note of phenomena that now is known to be caused by stellar aberration, which is a principal factor in the cause of stellar motion relative to the Earth (Campion, 2008).
A primitive lunar calendar
A primitive lunar calendar
Most of the major empires of documented civilized history have contributed to the development of astrology somehow, or at least have some unique interpretation of it. The Sumerians were responsible for the names of many common stars, and also created the aforementioned measurement system of degrees which was derived from their base 60 number system. Egyptians created calendars based on solar and lunar patterns, and used these calendars to mark dates of religious ceremonies. The Greeks are credited with the creation of astronomy which, although they approached it with as much rigor as mathematics, was closely tied with astrology at the time of its creation and onwards, with advancements in one affecting the other. Additionally, Olympian mythology was intimately related with stellar constellations, many names of which are still held today. The Islamic empire is also responsible for many of the current names of stars.

The European medieval age marked an evident repression of Western scientific development. Emphasis was placed on colonization and religious authority, and many of the sciences were viewed as an affront to religious doctrine. Particularly, the astrological tenet that human events could be predicted by observing celestial movement was viewed by religion as a challenge to the will of God. As a result, the medieval era marked a time of little astrological development, though Eastern cultures did not suffer the same impediment.

However, the sixteenth century brought about the scientific revolution, with many advances in mathematics, physics, astrology, biology, and philosophy changing the cultural priorities of the Western world. Although this gradually abolished fear of the church's sovereignty on scientific development, it also questioned position as a science. Particularly, Copernicus's heliocentrism, Kepler's laws of planetary motion, and Newton's Principia described the motion of celestial objects in ways that rendered the divine and supernatural aspects of astrology superfluous, and these new physical explanations for motion and causation challenged the mechanism by which astrological premises were effectuated. Consequently, astronomy became a strictly physical science, and astrology has remained as a dubious ethos.

Western Astrology

A fundamental tenet in Western astrology is that the entire cosmos is unified as a single living entity, and that the state of being that one aspect of the organism is in will be reflective of the state of others at that time, which is why predictions are made regarding the near future of the subject (Lewis, 2003). A commonly quoted epithet that encapsulates this belief is "as above, so below; as below, so above", indicating that the state of celestial bodies is an analogue to the state of earthly events, and the inverse of this as well. Some older schools of philosophy believed that mathematics could somehow explain this in the form of insofar undetectable wave-like energies emitted from planets, akin to the way in which sound resonates in objects other than the emitting one.

The skies are interpreted by viewing the paths of the planets (in astrology, the sun and moon are considered planets, as tradition held from geocentrism) across the sky over time. Each planet has their path divided into 12 sections corresponding to constellations in that area of the sky. These are the signs of the Zodiac, each of which represent a different basic human drive or personality type (Lewis, 2003). A subject (typically a person, though it can be any event such as a marriage or the start of a business) is assigned to one of these twelve signs based on the date of birth or genesis of the subject. This is called the subject's house. All of this information is presented via horoscopes, which are maps of the sky at a particular moment in time. Divination is dealt to an individual by taking their horoscope and analyzing the positions of the planets with respect to the signs of the Zodiac, the house of the horoscope, and in relation to each other.

Most horoscopes in popular media use a simplified version of this method, called sun-sign astrology, where only the Zodiac region where the sun is on a subject's horoscope is considered. This is the most common form of astrology that Western society follows, or at least is familiar with, though it is often criticized by serious astrologers as being meaningless and diluted.
The wheel of the Zodiac
The wheel of the Zodiac

Eastern Astrology

Eastern versions of astrology differ in that the interpretations and predictions made often deal politics, or the destiny of the subject. The beliefs are also more integrated within their respective cultures, likely due to the lack of religious conflict with astrology in the ancestry of the society.

Hindu astrology possesses many similarities with Western astrology due to their mutual Indo-European ancestry. Signs of the zodiac are still used, but a more complex approach is taken to mapping the Zodiac signs onto the sky, for the Hindus account for the movement of the Earth's rotational axis, which causes subtle shifts in the map of stars in the sky in consecutive years. Hindu astrology also asserts a fractal symmetry between what are called microcosmic and macrocosmic events in the universe which relate to sub-sections of their Zodiac regions (Pingree, 1963).

East-Asian astrology is drastically different. Although twelve Zodiac signs exist, each are assigned to a specific year rather than a partition of the year, and each are labelled as a different animal, which also symbolize a personality type. This astrology also has both lunar and solar calendars, which can combine to form the lunisolar calendar which repeats every 60 years (Wu, 2005). Chinese philosophies are closely related to the interpretations of the positions of celestial bodies, and many other aspects that are absent in Western astrology result in quite an apparently elaborate ideology.

Is Astrology a Science?


A common argument in defense of astrology is that, as mentioned above, only recently in history has it been marked as a dubious belief. Blame is often placed on the middle ages for permanently stunting the development and acceptance of astrology. However, many sciences survived this era, albeit completely modified by the scientific revolution, and no reason is given as to why astrology would have suffered more to this era than, for example, astronomy or physics (natural philosophy at the time). The fact that astrology has hardly evolved since this time is also posed as a reason for why it is not scientific.

It is also boasted that many great scientists have held belief in astronomy, such as Aristotle, Kepler, and Carl Jung. Not only is this clearly a misguided appeal to authority, and portrays a false image of dictatorship for all science, but most scientists who defended astrology did so in a time when it was regarded as a science and was almost indistinguishable from astronomy (eg. Aristotle and Kepler). In the case of Carl Jung, his scientific domain wasn't one where his opinions on the validity of astrology would carry much weight. He was also notoriously superstitious, calling immediate question to the reason behind this support.

Physical Claims

It is a confirmed fact that the gravitational field measured relative to the Earth changes depending on the position of the astrological planets, particularly the moon and the sun. There are countless atmospheric phenomena that are due to electromagnetic fluctuations caused by solar winds as well. Some astrologists argue that these facts support their theory to some degree. While it is true that these fluctuations exist, compared to much more trivial objects such as electrical appliances will cause much more drastic changes in these force fields compared to planetary movement. This also fails to explain why the force vectors present at a person's birth would trump importance to those present during childhood, or fetal development, or at any other time during a subject's existence. It also does not provide an algorithm by which these forces can be translated into predictions of future life events or personality traits. Indeed, one common argument against astrology is that no mechanism is proposed by which planets affect human activity. However, this argument by itself is easily refuted by stating that science is not required to propose mechanisms of operation; A mechanism for gravity wasn't accepted until Einstein's general theory of relativity in 1915, despite being widely accepted in science as a law of nature centuries before and having exceptional explanatory power since Newton's Principia in 1687. Precisely because of its explanatory power was the lack of a mechanism overlooked, and as will be demonstrated, astrology fails to do this, especially in juxtaposition with Newtonian gravitation.
Aurora Borealis, one of the many solar-induced electromagnetic phenomena on Earth
Aurora Borealis, one of the many solar-induced electromagnetic phenomena on Earth

It is also noted by astrologists that many physiological functions of animals, including humans, coincide with solar and lunar patterns. Most obviously, the sleeping patterns of land mammals are almost universally governed by night and day, but hormones are also affected by seasons, and some sea creatures are affected by the tidal patterns caused by the moon. This argument seems to be posing that if the sun and moon can have physiological effects on organisms, then it's plausible that it can govern human behaviour in a similar sense. This is an extremely misguided extrapolation, as there is no logical statement connecting physiological functions and personality traits. Darwinian science can also reasonably hypothesize why these physiological mechanisms exist in organisms, but cannot do the same for astrological assertions.

Experiments and Correlations

One study touted by supporters of astrology is colloquially referred to as the "Mars effect". In 1955, psychologist and astrologer Michel Gauquelin claimed to have found a statistical relationship between the position of Mars in the sky at a person's date of birth and their likelihood of being a professional athlete (Gauquelin, 1988). Similar to this study is the claim that people born in specific parts of the year are more likely to have success in some type of career, but what time of year and what career is inconsistent in different studies. Regarding Gauquelin's research, attempts to replicate his studies yielded inconsistent results, and eventually his method of data acquisition was analyzed to be suspect. It is also suggested that any correlation that exists may be due to the way in which education and sport organizations arrange their participants. The fact that, for example, all people born in a given year are grouped into the same school grade or athletic league may explain that individuals born in a particular part of the year may have an inherent advantage over others. An astrological explanation may not be necessary to explain such a phenomenon.

In contrast to Gauquelin's research, many studies testing the validity of astronomical predictions have yielded null results, most famously the Carlson double-blind experiment published in 1985 (Carlson, 1985). In this study, a group of astrologists were asked to match horoscopes at the time of a person's birth to their personality profile. Before the implementation of the experiment, its logistics were agreed upon by both scientists and astrologists alike, and the National Council for Geocosmic Research (N.C.G.R.) were allowed to choose their own astrologists for the experiment. The astrologists in the study failed to make correct pairings of horoscope and personality profile any better than chance would suggest they would (Carlson, 1985).

It has also been shown that if a personality description is vague enough, as horoscopes generally are, but has been apparently constructed in accordance with an intricate process (such as a lengthy interview), then people are inclined to rate it as accurate to themselves. This was demonstrated by Bertram Forer, a psychologist who gave his class identical personality descriptions and recieved an accuracy rating of 4.2 out of 5, which was also consistent for replications of this experiment (Forer, 1949). This bias explains why astrology seems to have powerful predictive powers.

Why Astrology is a Pseudoscience

Logical Positivism

Although a dead philosophy, logical positivism is worth considering in trying to define what is a science and what fails to be, not only due to its influence, but due to the fact that it is what many still perceive the scientific method to encompass.

Logical positivism asserts that a statement or hypothesis has to be verifiable if it is to be deemed meaningful in science (Bortolotti, 2008). Each statement can be verifiable in one of two ways. An analytically verifiable statement is one in which its truth or falsity can be logically established, independent of the information of the world. An example of these assertions are ones which asserts the quality of something that is inherent in it's definition, such as "all squares are flat". Squares are by definition two-dimensional entities. Other analytical hypotheses are those which take the form of deductive logical arguments. Synthetic statements are those which declare something about the nature or state of the world which can be verified through objective empirical measurements. An example of such a statement is the declaration that the boiling point of water is 100 degrees celsius.

In order to be verifiable, the statement must also be logically, syntactically, and semantically unambiguous. Therefore, sentences that contain meaningless or vaguely defined terms, or simply are incoherently structured cannot be scientific claims. This prevents nonsensical statements from being considered as scientific, but more importantly it establishes that ethical questions are not in the domain of science, because what is "best" or what is "ideal" is not well-defined. Lastly, supernatural and metaphysical questions cannot be verified, which excludes many religious and spiritual hypotheses from this definition of science as well.

Karl Popper's Falsifiability

Karl Popper took issue with logical positivism because no clear distinction between meaningful and scientific claims seemed to be made. If a statement logically and semantically coherent, it has meaning according to logical positivism, but according to Popper this didn't necessarily mean it was scientific, even if it became verified (Popper, 1963). Popper thought that verifiability was too inductive to be used as demarcation for scientific claims, as it inevitably would assert a universal claim from a finite number of observations. For example, logical positivism would claim that all fish have gills because the finite number of fish observed as of now have had gills, which is inductive.

Instead, Popper suggests that a claim is scientific if it can be falsified. The statement "all fish have gills" can be falsified by finding a fish that doesn't have gills, and each successive fish that is found is a test by which this statement can be falsified. According to Popper, the scientific value of a theory is determined by how easily it can be proven wrong in conjunction with how often it endures experiments which could potentially do so (Popper, 1963). This demarcation criterion for science manages to maintain the logical, semantic, and objective standards of the science of logical positivism, but does so in a way that doesn't appeal to inductive logic.

Paul Thagard and Pseudoscience

In reaction to the debates regarding demarcation criteria for science, Paul Thagard attempted to solve the issue by specifically defining what isn't a science rather than what is. In particular, he suggested some defining characteristics of pseudosciences, and used astrology as an prime example of a belief system consistent with these criteria.

Thagard considers a theory to be pseudoscientific if, despite many unresolved issues, little progression or development is made in the theory relative to similar hypotheses over a given period of time (Thagard, 1978). A distinguishing aspect of scientific study is that if there seems to be discrepancies with observation and theory, changes to the theory are suggested in order to reach a coherent resolution. The absence of this development is inconsistent with the purpose of science to explain natural phenomena, and may indicate dogmatic motives behind the theory. Similarly, Thagard also suggests that pseudosciences can be recognized by their lack of effort in addressing the problems of their theory, as well as a lack of recognition or consideration of competing theories. Pseudosciences also tend to be suspiciously selective with which observations they choose to recognize as potential confirmations or disconfirmations of their theories (Thagard, 1978).

Why Astrology Fails to Meet These Criteria

According to each of the bases of demarcation proposed, astrology fails on all accounts to be considered a science. With respect to logical positivism, astrological forecasts are not verifiable. Although they are logically and syntactically clear, they almost always appeal to the emotional state of the subject or to notions of success and fulfillment. The terms used are semantically vague and are subject to different interpretations and meanings, similar to prescriptive ethical claims. Therefore, they do not meet the criteria of a verifiable statement, and cannot be considered scientific.

It is for similar reasons that astrological predictions often fail to be falsifiable too. The ambiguous nature of horoscopes allows for nearly any outcome to be compatible with the prediction given. For example, if one's horoscope states that their efforts will be rewarded on a given day, the lack of specificity of this claim allows for any sense of reward to be consistent with it. It is hard to conceive of a day where no benefits are reaped, and consequently there are few circumstances in which such a statement would be falsified. The ability of this statement to hold true for almost any possible event eliminates its scientific value according to Popper's falsifiability. Additionally, in the occasions that the predictions made are easily falsifiable, they almost always are false, and in such circumstances astrological theory becomes an ineffective science, rather than not a science at all. Additionally, although some astrologists attempt to establish effects planets have on individual with established physical laws, many still maintain that some supernatural element is involved, and as already established, these claims cannot be falsified, let alone verified.

Astrology also meets Thagard's definition of a pseudoscience, which is evident as he basically models it as the standard for one. It's difficult to juxtapose astrology with another scientific subject, as it is a hybrid between the very physical science of planetary motion with the social science of psychology and sociology, but with respect to both of these, astrology has progressed very little. It still maintains traditions of definitions from geocentrism, such as the labeling of the sun as a planet, and often ignores many of the more subtle movements of constellations over centuries and millennia that have recently been discovered in astronomy. No unified attempts have been made to make astrological predictions more concise or verifiable, and the community hardly recognizes the alternative theories for the phenomena is predicts or suggests as evidence for its validity. Experimental evidence to confirm or refute astrological theories are often selectively chosen, or the results are often skewed in ways to misrepresent the data. Additionally, seemingly ignoring studies such as the Carlson experiment, astrology is often defended by stating that not enough studies have been conducted to confidently refute the discipline, and that funding should be supplied to do so.
Factors affecting stellar mapping, most of which are omitted by Western astrology
Factors affecting stellar mapping, most of which are omitted by Western astrology

Potential Harm

The harm that can come from astrology depends largely on how seriously one believes in it. Most of those who do follow their horoscopes likely do so casually, reading them for entertainment and not necessarily depending on or consciously thinking about it during their day. This is likely to be harmless. A serious follower could potentially plan their day unnecessarily around their horoscope forecast, causing needless complications and stress that could likely be trivial in most cases, but may occasionally become serious issues. Additionally, if one's horoscope involves emotional predictions, the expectation of feeling a certain way may cause that person to project such an emotion onto themselves when they otherwise wouldn't, which could be beneficial as easily as detrimental, but unnecessary either way, and may interfere with appropriate emotional reactions in some circumstances. Some serious believers may also stigmatize specific Zodiac signs, which would result in unnecessary social obstacles.

Eastern astrology may have much more serious consequences. As it is at least partly concerned with the destiny or potential of a subject, taken to extremes, this philosophy could result in an unwarranted cultural caste system, resulting in some degree of segregation and potentially inferiority of specific castes relative to others. In fact, in Hindu cultures, astrology is consulted when determining the compatibility of an arranged marriage.

Additionally, some confusion is sometimes made between astronomy and astrology, which is the cause annoyance to those in the former study. Below is a video of Carl Sagan discussing the differences.


Although astrology has an important place in the history of science, there is no valid reason to maintain its status as one. It meets none of the most accepted contemporary demarcation criteria for science, and is characteristic of an outdated theory that survives only as a pseudoscience. Although it is typically harmless if considered as entertainment, viewing it with any sort of explanatory merit should be avoided due to the potential social repercussions that may result.


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