OPA Astrology Store LogoTwelve Logical Fallacies Every Astrologer Should Know
Twelve Logical Fallacies Every Astrologer Should Know

robert curreyBy Robert Currey

“There are two ways to be fooled: one is to believe what isn’t true, the other is to refuse to believe what is true.” ~ (Kierkegaard 1847)

To most astrologers, debating astrology seems tiresome or even unwinnable. Perhaps you had an unhappy experience being ridiculed by some know-it-all in the family with slick answers. Don’t give up! The more you debate astrology, the more skilful you become. By reflecting on what you do, you also become a better astrologer. We are all ambassadors for astrology and our image will not improve unless more people understand the rationale behind what we do. This is not about winning an argument or trying to convert others or to promote astrology as a science. It’s education and all that is required is to take the critic through the logical steps to a point where there is only one rational position: suspend judgment of astrology until they’ve studied the subject and checked the evidence. The preamble to any discussion will probably start with a bit of popular myth about “the stars”. At this point you should firmly set out your definition of astrology. If your sceptical enquirer is just following feelings, then that is a personal belief and you can agree to disagree. However, if the critic is claiming that astrology is false on a scientific or logical basis, then let them make their case. You will be surprised to discover that it will be full of wrong assumptions and logical fallacies. The only tenable position for a scientist is one of doubt or agnosticism until proved otherwise.

Here are the top twelve logical fallacies to avoid and to identify:

currey text message1. APPEAL TO POPULARITY (argumentum ad populum)

– assumes that an idea or proposition is true because many people believe that it’s true. “Astrology has to be true. Look how astrology features in so many magazines around the world.” But equally “Astrology has to be false because the scientific consensus is that it’s not valid.” Most scientists are not interested in astrology and have no deep thoughts about the field. Criticism comes from the fringe of science. Many people believe that lightning doesn’t strike the same place twice. Nevertheless, popularity does not make this belief true. Lightning hits the Empire State Building in New York about 20 times per year.

2. APPEAL TO TRADITION OR APPEAL TO ANTIQUITY (argumentum ad antiquitam)

– claims that an idea that has been around for a long time is true simply because it has stood the test of time. “Astrology must be valid as it has survived for over four thousand years.” Again, so has belief in a variety of gods, creationism and even a flat Earth. What’s Logical about the Astrological? Quite a Lot! Twelve logical fallacies every astrologer should know. by Robert Currey

3. APPEAL TO NOVELTY (argumentum ad novitatem)

– asserts that that an idea is correct or superior simply because it is new and modern. This is the reverse of the Appeal to Tradition fallacy. “How can people still follow a primitive belief such as astrology?” Ancient wisdom has often been lost, only to be rediscovered centuries later. The Antikythera Mechanism is a twothousand-year-old analogue computer from ancient Greece. According to recent research, 3,700 years ago the Babylonians invented a long-hand method of calculating trigonometry that is more precise than those used today (Mansfield 2017). Note, that it was in this same region from around this period that the foundations of astrology were empirically discovered (Currey 2017).


– relies on the opinion of a supposedly reputable source to prop up a claim. “Since Professors Cox and deGrasse Tyson assert that astrology is rubbish, it must be false.” It also happens that these opinionated pop science presenters are clueless when it comes to astrology (see Uninformed Opinion). Unfortunately, the Press tends to confuse astronomers with astrologers and give them undue weight. But this fallacy is applied both ways. “Astrology preoccupied many of the greatest polymaths in history, Ptolemy, Al Buruni, Copernicus, Dee, Cardamo, Galileo, Kepler, Napier, Goethe, Ramanujan, Jung and the greatest novelists Chaucer, Shakespeare, and Rowling.” This means that astrology should be taken seriously, but it doesn’t make it true. Besides, more recent discoveries could have invalidated their views. (see Appeal to Tradition)


– assumes that a lack of proof is sufficient to make a claim true or false. “Since there is no proof that Pluto impacts life on Earth, it’s impossible.” Or the counter argument that “Absence of evidence is not evidence of absence” is only viable if you’re refuting an unsupported claim. Neither statement can be a basis to make a claim about astrology. The burden of proof is always on the claimant, whether pro or anti-astrology. In a rational debate, any claim must be supported by empirical evidence, otherwise it remains a belief.


– occurs when the arguer hasn’t bothered to learn anything about the topic, but nevertheless has an opinion. “Astrology is rubbish!” or “Astrology flies in the face of four centuries of evidence, from Galileo to the latest space probe.” (Jones 2011) or “…. that’s all rubbish, right, astrology, because the planets are in different places at different times.” (O’Briain 2011)


– happens when someone declares a “fact” without supporting evidence. “Astrology violates the laws of science!” Which laws? “Tests of astrology have shown it to be false!” Obviously, you would need an infinite number of tests to prove a negative. However, I have yet to see a single test that supports this claim. If you challenge a claimant to “put up or shut up” as skeptical magician Randi would say, establish in advance that tests that are based on Sun Signs alone, or a single astrologer or a magic trick don’t count. A quick search will confirm that any tests cited are either flawed in obvious ways or, after review, are shown to support astrology. But then, we claim “Astrology works!” This is fine for describing the astrologer/client subjective experience, but it does not make our claims objectively valid. A placebo works and is now an accepted tool in medicine. But to show that astrology also works on an objective level, assertion cuts no ice, we need statistical evidence that it works outside the astrologer/ client consulting room.


is to compare two different situations or views as if they are the same. “Astrology is like Racism” (Radford 2011). Some people use astrology to label people as stereotypes based on their signs, when the signs are archetypes and few people conform exactly to type. While this false assumption can lead to well-intended minor misunderstandings, it is not equivalent to racial prejudice and the resulting discrimination. There was no holocaust or slavery based on zodiac signs. It is wholly inappropriate, not to say distasteful and disrespectful to all, to make this comparison. This example is also an appeal to emotion fallacy, where emotion is used in place of reason to manipulate the argument. A fair equivalence would be to compare astrology with studies of blood group types.


– misrepresents an opponent’s position. This is done by replacing the opposing argument with a corrupted version. It is then easy to ridicule this much weaker argument and create the illusion of refuting the original position. “The constellations of the zodiac have moved and so the zodiac is out of alignment and astrologers are in error.” This old hoax has been pushed by people who know better. Having criticised astrology for years, Richard Dawkins, only attacked the soft target of SunSign astrology when given the opportunity by Channel 4 (UK) (Dawkins 2003).


– debunking an idea based on its origin and the motivations of the proponent rather than addressing the substance of the argument. This includes ‘Argumentum ad hominem’ which is to attack an opponent’s authority, character or other personal traits to undermine his or her argument. “We can dismiss his evidence as he’s an astrologer. He must be biased as he makes a living from astrology.” Yet, the best evidence can only come from experts in the field. Any argument or evidence presented by an astrologer or a debunker should be judged on the merits of the case and supporting evidence not on their affiliation or vested interests. However, if a critic portrays you as being biased, there is no harm in pointing out that he or she is a member of a sceptical group. But it’s still not an argument.


– asserts that a relatively small concession inevitably leads to a significant development that is extreme and unacceptable. “If we don’t quash Gauquelin’s evidence of an eminence effect, where do we draw the line? Fairies, Unicorns?” (another example of False Equivalence) When you know that you’re wrong, always be prepared to concede openly and with grace. The case for astrology is robust enough to survive. For example, don’t try to defend all astrological techniques or all astrologers. No doctor would defend all doctors. Hard core critics are often too overwhelmed by cognitive dissonance to admit to being wrong and tend to dig themselves into a hole defending an indefensible position.


– to start with a false claim then use it in reverse as if to prove it. “Astrology is pseudoscience, as it is not published in Scientific Journals. Scientific Journals should not publish articles on astrology, as it is a pseudoscience.” In practice, scientific journals refer papers on astrology to astrological journals who publish both positive and negative articles on astrology. “Astrology could not possibly be the explanation for this effect, as astrology is too implausible.”

Once all the posturing has finished, there are only two issues that need to be addressed.

THE FIRST is how does astrology work in a physical sense? It’s really the job of science to find a mechanism to account for all the evidence. Such a discovery would be a great boost to science, especially astronomy which is often criticised for having little relevance to human lives. Unless you have studied physics and various possible mechanisms, it is better to concede that we don’t yet know the mechanism. Then, either point in the direction of Percy Seymour’s book: The Scientific Proof of Astrology (1997) or if you subscribe to the Jungian model, explain your belief in synchronicity.

THE SECOND valid logical argument is – what, if any, empirical evidence supports astrology? These days there are a growing number of compelling experiments, but this is beyond the scope of this article. A final thought is that some astrology critics advocate scientism – the belief that only science can render the truth about reality. They sincerely believe that they are defending science and reason. In reality, they are religiously defending their personal beliefs based on prejudice and strong emotions. Most have no respect for the scientific spirit of open enquiry, and if challenged, some become abusive and mocking. Most are not scientists. Nor are they sceptics in the true meaning of the word. The irony is that since you came into astrology by questioning conventional wisdom you are more of a sceptic – you, the astrologer, the critical thinker, who is now defending logic.



  • Currey, Robert (2017) OPA June Solstice pp.29-30 Dawkins,
  • Richard (2007) Enemies of Reason, Part 1. Channel 4, UK. Aired 13 August 2007.
  • Jones, Steve (2011) A review of Impartiality and Accuracy of the BBC’s coverage of Science. BBC Trust Report Mansfield, Daniel & Wildberger, Norman (2017)
  • Plimpton 322 is Babylonian exact sexagesimal trigonometry. Historia Mathematica, August 2017
  • O’Briain, Dara (2011) Stargazing Live. BBC2 TV Radford, Ben (2011) How astrology is like racism. Radford is deputy editor of the Skeptical Inquirer, Seymour, Percy (1997) The Scientific Proof of Astrology. 

About Robert Currey
A scientific investigation as to how the stars influence human life. Quantum Robert Currey was one of the first astrologers to write astrological software. This led onto his business Equinox, which has offices in the UK, USA and Australia. He has a FAS Diploma (London 1985), Robert Currey awarded the Charles Harvey Award for Exceptional Service to Astrology (2017) started the Astrology Shop in central London in 1989, qualified as an Astro*Carto*Graphy Interpreter (San Francisco 1995) and received a lifetime achievement award (Kolkata 2016). Nowadays, he is a consultant, lecturer, author and researcher.

For more information about Robert Currey, visit: www.equinoxastrology.com