Hundreds of tests have shown that astrologers are no better at predicting events or people's personality traits than random guessing. Somehow I'm not surprised. A field of research that does not require you to show your work or verify your theories is bound to attract charlatans and incompetents. However, most reports on these tests seem to take the viewpoint that these tests disprove astrology, which is a completely unscientific claim to make. For instance, one arrogant asshole at skeptico.com said that the fact that astrologers who failed Shawn Carlson's double-blind test of astrology didn't "g[i]ve up astrology as being useless" means that they were "totally closed minded to the possibility that astrology doesn’t work," rather than consider that their methods need to be refined. Even what I consider the best study into the premises of astrology was reported in the Telegraph as evidence that astrology is "rubbish." (
http://www.telegraph.co.uk/news/uknews/1439101/Astrologers-fail-to-predict-proof-they-are-wrong.html) Actually, what is shown is that the claims of astrologers can be demonstrably wrong and the astrologers themselves have no accountability for their claims. This is serious and important on its own, but to take that information and make the leap that the time and location of your birth has no effect on you personally is scientifically unsound and unsupported by evidence.
In various studies, there has been shown to be correlations between time of birth and such factors as longevity, birth length, time of onset of menopause, and suicidal tendencies. (Taureans and Sagittarians live longer, Leos and Aquarians live shorter, Scorpios are born taller, Taureans are born shorter, Libras start menopause later, Aries start menopause sooner, and Taureans are more likely to hang themselves.) This means that there are physical and developmental differences based on month of birth, and there are likely to be psychological ramifications. What these ramifications are isn't really known. Most skeptics will tell you that there has not been any correlation found between personality traits and month of birth. This isn't really true, but even if it were, it should be noted that there is no entirely accurate way to test a person's personality and self-reported personality tests are notoriously inaccurate. Michel Gauquelin tried to remove this inaccuracy by analysing famous people whose personalities and prominence were known. Based on this, he noted the "Mars Effect," based on the position of Mars in their astrological charts. Though his findings are often quoted, they should probably be disregarded, because his samples weren't at all random.
There is a marked correlation between "positive" signs (Aries, Gemini, Leo, Libra, Sagittarius, and Aquarius) and extroversion, as well as between "water" signs (Cancer, Pisces, and Scorpio) and empathy and neurosis. What is even more important to note is that this correlation only exists among people who are aware of their astrological signs. So it may very well be that to a large extent, astrology is a placebo. However, it is a placebo that is historically relevant and very prevalent in our society. That is to say, the correlation exists even though the reason has nothing to do with celestial bodies. The larger issue, and one that I find much more interesting (and yet few people seem to bring up), is that if the correlation depends on knowledge of one's astrological sign, that implies that these personality traits are self-determined and can be altered through suggestion - either that or it's just another example of the flaws of self-reported personality tests and the findings are pretty much meaningless.
Since the scientific validity of astrology has not been confirmed and astrologers can't be trusted to tell you anything necessarily true, it is easy to say that astrology is bullshit. However, I contend that mythology and metaphor and pseudoscience are not detrimental and can actually be beneficial, provided they are not confused with real science. I was going to write an essay about the real value of astrology, but I saw that former astrologist and current astrology debunker Geoffery Dean already did a pretty good job of that, which I would like to draw your attention to:
http://www.astrology-and-science.com/a-basi2.htm References used:
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