Debunking Astrology in 200 Words

My tolerance for pseudoscience is in retrograde.

Erik Devaney


Let’s rip the Band-aid off, shall we?

Two double-blind tests from 1985 confirmed what critical-thinkers have known since the Enlightenment: astrological “natal charts” cannot accurately predict personality traits. The positions of the stars and planets when one is born have no measurable effect on how one turns out personality-wise.

Translation: astrology doesn’t work.

An Exercise in Vagueness (Not Divination)

‘An Astrologer Casting a Horoscope’ from Robert Fludd’s Utriusque Cosmi Historia, 1617

While proponents of astrology may genuinely believe that their horoscopes (i.e., interpretations of their “star charts”) are accurate, there’s a psychological explanation for this: the Barnum effect.

The Barnum effect (a.k.a. the Forer effect) is the natural tendency for humans to think that information is tailored specifically to them, even when that information is so vague as to be useless (e.g., “You will face a challenge at work this week”). Many psychics, fortune-tellers, aura-readers, and even some personality test creators exploit this same effect.

And there’s another problem…

The Earth wobbles. As a result, the celestial bodies we see in the night sky today are not in the same positions they were 2,000+ years ago when the first star maps were made.

Since modern astrologers still rely on these outdated maps, zodiac signs — which are assigned based on the position of the sun relative to certain constellations at the time of a person’s birth — are all off by about a month. Thus, most Aquariuses are actually Capricorns, most Capricorns are actually Sagittariuses, and so on.



Erik Devaney

Full-time stay-at-home dad, part-time ghostwriter, retired pub musician, recovering marketer