Why Astrology Works

It seems to me that in broad outline there is some truth to astrology. Certainly not in the ability to predict the future or anything like that, but there seems to me to be something to the general personality traits that each sign of the zodiac is assigned. For instance, Libra’s are said to be indecisive and tend to get along with Sagittarius etc…I am usually mocked for saying things like this, but I think that, inductively, these generalizations hold up (minus the ceteris paribus clauses…). So then the question is why do they? It seems to me that one can give an argument along the following lines. We know that the moon affects the tides and other rhythmic properties of liquids here on Earth. We also know that the moon has a profound affect on the mood and general state of mind that people are in (hence our word ‘lunacy’). It is no surprise then that other heavenly bodies should have an affect on the general functional properties of the brain. The alignment of the stars can be seen as an indirect way of measuring the net gravitational effects of the nearby heavenly bodies on the functional properties of the brain, and so on general personality traits (mostly due to the chemistry of the brain.)

10 thoughts on “Why Astrology Works

  1. You stated-We also know that the moon has a profound affect on the mood and general state of mind that people are in (hence our word ‘lunacy’). –
    Please do expound. It was my understanding that inthe past, it was ‘believed’ that lunar cycles affected behaviour, giving rise to the “lunacy,” not that there was any actually correlation. If there is a correlate and data supporting such, I would enjoy reading it. This does not mean that I am pointing out fallacies in your argument. Rather, I am ignorant of the issue would like to know more. Thank you.

  2. Interesting analysis! I always thought that the way the personality traits were grouped together in astrology was non-random. For example, it makes sense to say that a Pisces is sensitive and compassionate, because someone who is sensitive is also likely to be compassionate (intuitively it seems these two traits draw from the same cognitive resources). If it has nothing to do with astrological works, maybe it was first conceived off inductively and in some careful way that took into account people’s observed personality traits, or maybe it is more legitimate in the way you suggest. Either way it does seem that the traits are organized in some psychologically sensible way.

  3. I think a better answer to ‘why astrology works’ would be confirmation bias.

    For a better test than selective recall, see if you can guess others’ star signs with results better than chance.

  4. Hi Jaymeesd,

    Yeah, it turns out you are right. I thought there was some data on this, but when I researched it it turned out to have been discredited. So I retract that statement. Thanks.

    But I don’ think that it affects the strategy of the argument.


    Thanks for the comment!

    You may be right that a lot of it is based on careful and long term analysis, but then you would still need to explain how it is that positions of the stars gets correlated with the psychological tendancies.


    I take the point about confirmation cias, but there is also another kind of evidence that stems from noticing (after the fact) that my compatibilities are quite in line with those predicted by my sign. So, a poll of those close to me reveals a pattern of signs. I get a long with some and don’t with others and this lines up witht he compatibility predicitons made by my sign. That isn’t confirtmation bias!

  5. Thank you for answering that for me. You are quite right, that one statement does not change your argument at all.

    As per Richard’s comment, I did try to both figure out whose sign was what from their personality traits and guess the signs of others I don’t already know.

    However, I already know all of the birthdates, and inasmuch the signs, of all of my mates. It was quite a task trying to remain objective to assign dominant traits to them and seeing if they matched their signs. It was quite an interesting psychological experiment for me.

    It ended up with me “seeing” all the traits that their respective signs gave them. For example – “Yes, Jacob can be stubborn at times. He is a scorpio.” This is regardless of whether or not the person was predominately his assigned trait(s). So, I don’t know. I think now I shall try to guess the signs of people I have more recently become acquainted with and see how it goes.

  6. If astrology does have an effect I wont be the stars that are causing it, it would be the moon and the sun and objects that cause significant effects. So there should be a better way to model it.

    I am also inclined to think that any effect, even of the moon, would tend to be dwarfed by effects due to parents or schooling and genetics. Speaking of which it is also possible that for whatever reason people who are stubborn tend to have sex around 9 months before the Scorpio period.

    If I had to make a call I would expect the effect was negligible – I don’t think I have many traits from my starsign.

  7. Richard,

    This post stands in stark contrast to the many plausible things you have to say. I am suprised that neither you nor your commentators have rehearsed the most common arguments here. What plausible explanation marks the importance of the causal influence that the stars have on a fetus/newborn at the moment or day or month of birth? Whatever effects heavenly bodies have on new borns, they travel through planets, ceilings, floors, walls, kitchens, stocked shelves and whatever else might stand between a newborn and heavenly bodies. A pregnant woman’s body does not block the causal influence of heavenly bodies anymore than a few floors in an apartment building or the flesh of dozens/hundreds of live and dead animals across the earth. Astrology has no plausible explanation for how astrological signs allegedly exert the causal influence they do when they do, as opposed to other times/dates (when, according to astrology, different astrological signs would be more at work and more effective on different kinds of psychological development). I could go on with some more of the standard arguments, but you can find them in pseudoscience books and websites. How could you have overlooked or compartmentalized them?

  8. People might modify their own personality to conform to their astrological sign. That is, it could be that people first learn the traits of their sign, then a confirmation bias convinces them of it, then they further confirm the traits by acting in accord with them, and finally you can thus guess their astrological sign by observing their behavior. That is, the fact that your observation is predictive doesn’t rule out confirmation bias as the explanation, it only rules out your confirmation bias. To me, the strongest candidate is some kind of confirmation bias, such as the Forer effect.

    I doubt that any gravitational influence is responsible, people just aren’t consistent enough in the direction that they face and the Earth also spins, which seemingly would average out the influence of extraterrestrial gravitational sources.

    But there are many people whose psychology is affected by the seasons (e.g. Seasonal Affective Disorder). Many animals are driven to different behaviors at various times of year, and so it would not be totally unreasonable that human beings might also have behavior-affecting hormonal shifts at different times of year. Such shifts, if they exist, could affect the developing infant in the womb.

    I’m not saying that this explanation works, or even that astrology works, just that there could be a rational basis for the kind of general correlation with personality traits that you noted, one that doesn’t depend on confirmation bias. This explanation, however, seemingly should depend on birth latitude.

    There is another possibility. It could be that your observed correlations are just random chance. After all, about 1 in 20 randomly-chosen independent phenomena will have statistically-significant correlations (at the 95% confidence level). Anyone who looks for odd correlations is almost sure to find them somewhere. Just look at all the superstitions surrounding sports. Informally, people tend to become convinced about correlations far in advance of a 95% confidence. But even at that 95% level, many such statistically-significant correlations (maybe even most of them) are meaningless.

    Consider how many people on the planet have considered whether the people they know follow the astrological predictions of personality. Maybe hundreds of millions? If it were just 100 million, then 5 million of those would find a statistically significant correlation, just by chance. So to rule out chance in any one person’s report, even your own, you need an extraordinarily high confidence level. You might randomly sample enough of the population of these observers that you know if the statistically-significant finding is the exception or the rule.

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