The Scientific Argument against Astrology

The scientific argument against astrology is strong, yet astrology thrives. Some people even believe that an argument against astrology is an argument against astronomy, conflating science and pseudoscience completely. Then too, horoscopes are usually flattering, exciting, and vague enough that some part of their assessment seems true. Understandably, many people believe in horoscopes, but science does not.

Action at a distance

No one can wave their hand and make a bowling pin fall down. They must push it, shoot it, squirt it with a high pressure hose, or roll a heavy ball into it. Outside of astrology, few believe that action at a distance has an effect without a reasonable explanation of how a motive force is transmitted.

Neptune is 2.68 billion miles from earth at its closest approach. How does it transmit the power to shape the life or personality of any child it casts its mystic rays upon? The sun, of course, is a mere 93 million miles away or so, so its influence may be stronger.

Testing astrology’s predictive power

Shawn Carlson, who earned a PhD in nuclear physics and held a MacArthur Fellowship, tested astrology’s predictive power. He led a group that generated 100 psychological profiles using a well-known personality inventory to test subjects. The group then challenged 28 practicing astrologers to match the profiles to natal charts of the subjects. According to his study, which was published in Nature, the astrologers did no better than chance.

Testing time twins

In London in 1958, more than 2,000 infants were registered at birth, in order to follow them through life and compare their life circumstances and outcomes. In 2003, Geoffrey Dean and Ivan Kelly reported in the Journal of Consciousness Studies that time twin children with identical astrological charts did not show the similarities of personality or circumstance that astrology would predict.


Some astrologers make statements general enough that they could be true of anyone, at one time or another. Do your own experiment by cutting out newspaper horoscopes, removing all trace of the sign they originally referenced, and distributing them randomly among a group, telling each member you have downloaded their horoscope. Odds are good that some of your friends will find validity in predictions they believe refer specifically to their sign.

Astrologers are no doubt sincere. However, unconsciously perhaps, they make general predictions that could apply to anyone. Furthermore, their assessments tend to be flattering and positive, which also encourages belief.

Astrology does no obvious harm, unlike smoking. However, it does encourage an unfortunate habit of mind. People who base their behavior on horoscopes apparently believe in something that scientific research shows is not a reliable guide.