When evaluating the plausibility of astrology, it seemed to me that there was no good reason (based on existing scientific knowledge) to expect the claims of astrology to be true. Given this, I thought to evaluate its prophetic claims, but the predictions that were readily available (such as the regular horoscopes printed in most newspapers) were too generic to be testable. Considering that each of these predictions could generally be applied to 1/12th of the Earth’s population, they tended to be too generic to have any predictive power at all. In the end it seemed to me that the only way in which I could properly evaluate the predictive power of astrology was to obtain a more personal prophecy.

For this purpose I purchased a comprehensive personalised astrology report from the Australian company Astrologic Answers. The report would apparently be “calculated” from the data of my birth and emailed to me after a few days, along with a complimentary ebook entitled The Art of Astrology. See the end of my previous post on astrology for the details of the data I provided and the insight I was promised in this report.

Since receiving it, I’ve read through the report a few times, and I found more or less exactly what I’d expect to find if astrology were not true: All statements were fairly generic, and whereas some seemed rather accurate there were many others that didn’t describe me at all. I also saw several ways in which someone unaware of their own biases might be convinced of the power of astrology by this report. I’ve made the full personalised report available as an attachment if you’d like to read it: Astrological Birth Chart

Perhaps the first thing that struck me as suspicious when reading the report was a disclaimer in its introduction:

When using these interpretations, please bear in mind that, inevitably, every chart will contain some contradictory influences, and as a result certain interpretations of different items in the same chart may seem difficult to reconcile. However, this may still be an accurate reflection of your chart, as it is likely that you do experience conflicting desires, events and circumstances in your life.

At first I decided to award them the benefit of the doubt; perhaps for the particular contradictions they had in mind their excuse was appropriate. However, as I read the report I noticed some contradictions that I felt could not be reasonably justified by this. For example, within the “Life Goals” section under “The Sun is in Gemini”, the report essentially seemed to be talking about how much of an extrovert I am (although I’m really not). Later, however, several statements seemed to more accurately describe me as an introvert.

For example, here is a statement describing me as extrovertive:

You’ve a tendency to liven up even the quietest environment, sometimes even introducing a chaotic element. Life is never dull around you.

Here is a contrasting statement from later in the report describing me as introvertive:

Your home needs to be your haven from the world because at times you feel overwhelmed by the harsh realities of the world, and you need to shut away.

Although these claims are not directly opposed to one another, they do describe certain personality aspects (extrovertism and introvertism) that are fairly diametrically opposed to one another. Of these two examples, I consider the first to be very inaccurate that second to be very accurate.

It occurred to me that, when combined with the disclaimer, these different statements could be seen to have accurately predicted any combination of extrovertism and introvertism. In this case, the disclaimer dismisses the description of my extrovertism as a minor quality, as the description of my introvertism is obviously more important. However, were I more extroverted, the opposite could be said to be the case. It seems the astrologer cannot lose, which essentially means that these statements have no predictive power.

Various statements in the report are qualified in a similar way to this one:

Depending on other aspects in your birth chart, you simply can’t relax in dirty or untidy surroundings, and become quite agitated until something is done.

Such statements seem to offer a perfectly legitimate excuse for false predictions, while also allowing correct predictions to count as positive evidence for astrology. In this case, I find that I can quite easily relax in untidy surroundings (as the state of my bedroom can attest), so obviously the other aspects in my birth chart meant this prediction doesn’t, in fact, apply to me. However, if this prediction were true, then it would surely be counted as a success attributable to the powers of astrology.

Again, given that it seems impossible to interpret this statement in such a way that shows the astrologer to be wrong, it cannot be seen to have any predictive power.

The astrologer also hedges their bets in this report by qualifying some of their statements with words like “maybe” and “perhaps”. For example:

One of your parents, perhaps your mother, was a strict and severe influence

In this case, if my father was a strict and severe influence but my mother was not, then it is not to be counted against the astrologer as they were not certain that they should be talking about my mother. However, if they were correct about my mother, then of course I should count this suggestion as prophetic.

As before, this “no lose” scenario for the prediction robs it of any utility. It is more an enforcer of confirmation bias than a potentially useful (and testable) prediction.

All of these excuses that have been readied by the astrologers, to be used immediately but only if necessary, remind me very strongly of the backfire effect. It is remarkably uncommon for an incorrect prediction to lead to the abandonment of a belief.

For example, in the 17th century William Miller predicted that Christianity’s long-awaited “Second Coming” would finally come to pass in the year of 1844, which was later narrowed down to the 22nd of October. Of course, this prophecy failed, but that didn’t result in all of Miller’s followers simply abandoning this superstition. Instead, many of them simply decided that the prophecy was correct in all but a few details, and it actually predicted another event on that date (which was conveniently undetectable). This is how the Christian denomination of the Seventh Day Adventists started – by refusing to accept that a prophecy had failed *.

More benign superstitions will show the same phenomenon. If nothing bad happens to you on Friday the 13th it’s not because there’s nothing special about the date, but because you were “lucky”. Likewise, if no evidence can be found to support a conspiracy theory, the very lack of supporting evidence itself is seen as evidence of a cover-up.

Overall, I felt that the astrology report was very hit-and-miss. Some of its predictions, while still very general, seemed relatively accurate, whereas others didn’t seem to describe me in the lease.

In order to illustrate how the claims made in this report could be made to apply to anyone, I recommend you try what I did after reading through it a couple of times: Read through the report, keeping in mind that it was written to describe not me, but Batman. I think you’ll find it to be surprisingly accurate… Indeed, I found it seemed to describe Batman better than it described me, overall.

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* I haven’t done the narrative of the Millerite movement justice with my brief description of it here, and I highly recommend you read more about it. It’s certainly a fascinating case.