In 1995, I read a scientific paper in a journal – a real, live, on-the-shelf-in-a-library journal – that was to become the article that I have cited the most, ever. Unfortunately, I have lost the actual reference, which disappoints me greatly.
The author started off by making two simple assumptions.
The first assumption was that zodiac sign under which you are born significantly affects your likely personality.
This is obviously controversial assumption, but please, just accept it for now.
Note, though, that this is a very broad assumption. It is not saying that stars predict your future. It is not saying that all Leos are argumentative or any other specific trait. It is not saying that all Aries are the same. It is not offering a mechanism by which the stars affect your personality. It is not ruling out that personalities might be influenced by societal pressure to conform to assumptions about stars-signs. It is just assuming that, in some general way, astrology has some basis as a method of categorising personalities.
The second assumption was that personalities significantly affect job choice.
This is a fairly innocuous assumption. I can look around at the people in several industries that I am familiar with, and see that there are clear biases in the personality populations.
With these two assumptions, it should be clear that if you were to compare the distribution of birthdays of the general population (which is a fairly even distribution, but there are biases towards certain times of the year) against the distribution of birthdays of, say, baseball players, you might expect to see a significant difference. It isn’t clear from the assumptions which direction the bias(es) might be, but there should be at least one. Of course, you would need to have a reasonably large sample to be sure.
At this point, the author revealed that he had access to a publicly-available database of the personal statistics of 10,000 US professional baseball players, including their dates of birth. So he compared them and discovered that there was (oddly enough) no statistical difference.
Maybe this was some unexpected anomaly related to baseball, but no matter, because he also had access to a database of medical doctors. Again, there was no statistical difference.
So, he tried again, with a database of lawyers… and again, and again, each time with different professions that, it seemed clear, would be inviting to different personality types.
Each time, he found no significant difference between these large samples and the general population.
One of the assumptions that he started with must be wrong. It seems pretty clear which one it must be.
I found this paper quite delightful, for two main reasons.
I had heard (and made) attacks against astrology in the past that had:
- questioned the size of the impact that distant stars could have, explaining how the effects of gravity, magnetism, etc. dissipate over distance
- explained how the stars in each zodiac symbol are nowhere near each other, and that the shapes of the Zodiac are human interpretations, based on our location in space.
- explained how the Sun now “rises” through the zodiac symbols during different times of the year, compared to dates determined by Ptolemy.
- described how confirmation bias, Forer’s effect and wishful thinking add up to explain the perceived effect of astrology.
- debunked how modern “astrologers” actually produce their predictions.
This paper, however, showed that there was no need to muck around with the intricacies of astronomy, gravitation or psychology. You don’t need to debunk the proposed mechanisms or use Occam’s Razor to find better explanations of the effect that stars apparently have on our personality if you can simply show that there is no effect to explain.
The second reason I found the paper delightful was the summary. The author explained that he had been very careful with all of the statistics, checking all of his figures and methods very carefully. He had considered both sides of the debate and provided a balanced and measured argument. He had been fair and without bias. His evidence of this?
“Because I am a Libran, and that’s how Librans are.”