The Instigator
Con (against)
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The Contender
Pro (for)
7 Points

On the balance - Astrology makes accurate predictions

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Post Voting Period
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after 1 vote the winner is...
Voting Style: Open with Elo Restrictions Point System: Select Winner
Started: 9/10/2014 Category: Science
Updated: 3 years ago Status: Post Voting Period
Viewed: 1,717 times Debate No: 61494
Debate Rounds (4)
Comments (11)
Votes (1)




Pro must present evidence to show that predictions made by Astrology are significantly accurate.
Con (myself) must present evidence to show that predictions made by Astrology are not significantly accurate.
BoP is shared. Voters require at least 1500 elo. Point system is "Select Winner"
Round 1 is acceptance. After that, debaters are free to argue as they deem fit.


This seems like a bit of a steph, but I accept the debate.

To prove my case I will make an Astrological prediction that is provably, and significantly accurate in Round 2. I will then prove its significance in round 3 with evidence, and provide a final rebuttal in Round 4. This will be to prevent my opponent from selecting someone who is just making random Astrological claims, and proving the random passerby wrong. After all I can find someone who claims to have used Science to build a perpetual motion machine, and prove them wrong. However, that doesn't prove that Science is false. It only proves that person was wrong.

I'd also like to define Astrology, and some other terms upfront before we get to far into this. Astrology is any system that uses heavenly bodies in relation to ones birth to predict possible outcomes for an individual. Heavenly bodies are most commonly refereed to, but not limited to, the Earth, Sun, Moon, planets, and stars. Finally, for significance I'd like to only use statistical significance because we be leaving the audience, and the voters a lot of subjective room to judge otherwise.

Thank you, and lets begin.
Debate Round No. 1


Thank you for taking this challenge. Also, thank you for defining Astrology. I often take definitions for granted. For example, I used the phrase, "On the balance" which implies that we share a burden of proof. In the case of Astrology, a prediction is a testable claim made about the future. Obviously, we cannot debate future events. Given that Astrology was formulated a long time ago, I don't expect to argue that predictions made by Astrology were made after the fact.

I hope that it can be inferred from my topic and the challenge description in round 1 that I did not intend to say that there are zero predictions made by Astrology that are accurate. After all, the chance that I will get a prediction correct goes up with the number of predictions I make, and Astrology makes a lot of predictions, each applying to a large group of individuals. The number of predictions is even higher when given the consideration that there are many forms of Astrology, and Pro has included all of them in his definition of Astrology.
Rather, if we were to enumerate all the predictions made by Astrology and to pick one at random, Astrologers would expect that the probability of that prediction being true is either 100% or close to 100%. However, such an experiment has not, to my knowledge, been conducted, and we have no database of predictions to draw from. Therefore, the most reasonable way forward is for the two of us to select predictions we feel best support our case. I hope this is not a deal breaker for you. If this clarification causes you stress, I will agree to a tie debate at your request.

Opening Arguments
Berkley University set out to test the claims of Astrology [1]. In their analysis, they stated that many of the claims made by Astrology are not testable claims. So they took a few of those that are and put them to the test and found them false. For example, Astrology makes claims about which Zodiac signs make the best leaders: Aries, Cancer, Libra and Capricorn [2]. Most people who have heard about Astrology understand that Astrology provides a daily horoscope based on one's sign which was determined by their time of birth. Astrology provides multiple signs based on one's time of birth, most of which are tied to a specific heavenly body. The daily horoscope is usually based on the sign assigned to the Sun.

One very tantalizing test is to examine the signs related to US presidents. The Berkley study showed random variation of the Sun signs of the presidents [1]. One website that supports Astrology gives a detailed analysis of the Sun, Moon, and Mars signs for presidents, and gives statistical analysis for the findings [3]. The lack of statistical significance of Sun signs is agreed on. What the analyzer points out when you total the signs for these three bodies, there are statistical outliers. We would expect the signs of leaders to stand out. Here is a table of their results. I have listed them from most common to least common, putting an * after the four signs that are predicted to be leaders by their sign. For some reason when I use the table HTML tag, it shows a lot of blank space in, so I have provided this table at the very bottom of my argument after the references. There is an even distribution of leader signs in this analysis. The highest ranked leadership sign is Capricorn in third place. The lowest ranked leadership sign is Pisces tied for last place. This does not stop the author of the study from agreeing with Astrology. He looks at the data and reasons backwards from the data as to why the signs that are common, even applying logic to specific points in time. For example,
According to the historical patterns, having the Moon or Mars in Pisces is a definite negative. Having the Sun in Pisces isn't so good either, since all four presidents with their Sun in Pisces held office in the nation's first century. George Washington (1788), James Madison (1808), Andrew Jackson (1832), and Grover Cleveland (1884) were our only Pisces presidents, and it may be that the Pisces natural selflessness doesn't come across as being assertive or bold enough in more modern times.

Although the author is a good source of reliable information about the signs of the presidents, the author fails to show that any of the outcomes of the presidents lives were predicted by Astrology. However, when we look at the predictions made by Astrology and compare them with the data presented, they do not match.

John H. McGrew and Richard M. McFall from the Psychology Department of Indiana University conducted a small test in which astrologers were given full details of 23 volunteers lives and were asked to match them with their birth charts. The conclusion was that the astrologers failed to do better than chance. They also failed to do better than non-astrologers who attempted the same task. Furthermore, they failed to agree with each others predictions with any degree of statistical significance [4].

In my research, I have found that scientific evidence for Astrology isn't agreed upon by different astrologers. For example, try asking the question which zodiac signs are most likely to commit murder. According to one source, the Sun sign for murders are Gemini, Virgo, Sagittarius and Pisces [5]. According to another source, there is no link between the Sun sign and murders whatsoever. It is mostly the Mars sign that matters, and how it interacts with the moon sign [6].

Consequently, it is important that studies that show the predictions made by Astrology are accurate are reproducible. Wikipedia gives one example of a study done by an astronomer which showed a relationship between athletes and their Mars sign. It has yet to be reproduced [7].

So when we look for scientific evidence for Astrology, we need to use the same criteria we use to test other scientific claims:
1) There is a prediction made
2) The prediction is falsifiable when tested
3) The test is reproducible

I have already shown that astrologers don't always agree with each other when making predictions. They have also invalidated each others scientific claims. The sources I have given that favor Astrology all use backward reasoning; they create their predictions from the observed data instead of the other way around.

Again, I apologize for the table being so far down. I couldn't figure out how to fix the spacing issue.


Leo 310417
Scorpio 57416
Capricorn* 44614
Taurus 43613
Aquarius 53311
Libra* 44311
Virgo 25411
Cancer* 42410
Sagittarius 3248
Gemini 2147
Aries 2114
Pisces* 4004


Depending on where you are in the world Astrology is one of the few surviving ancient sciences. India, and China happen to have a stronger ties between Astrology and Science than the western cultures of Europe. Western Astrology has mostly become entertainment, and lacks the academic background needed to create accurate predictions using Astrology. The Western Zodiac is also under developed. In part, over 300 years of academic neglect will halt development, but even a thousand years ago the Chinese Zodiac was far more developed. The main difference between the two is that the Chinese Zodiac can track in as long as 60 year cycles, and as short as 2 hours cycles. Western Astrology has a hard enough time with monthly cycles that normal people can grasp.

For the purposes of this debate I will only prove the predictive value of Astrology. I do not intend on proving any claim of causation. The reason for that has to do with the base reason for Astrology. The primary purpose of Astrology is tracking time, and location. The most basic claim that Astrology has is that when, and where you were born has a direct influence on who you will become. I only intend to show that Astrology can predict, and not claim anything about the stars causing anything.

Each of my claims will be backed up by scientific research, or raw data that shows statistical significance in the next round.

For people born in the UK, and most of Europe, in the months of the Ox, Tiger, Rabbit, and to a lesser extent the Dragon children will be more successful at sports in their younger days. If they pick a sport of skill like baseball this will continue into professional sports. If they pick a game of size, and strength they will encounter great adversity if they choose to continue into adulthood.

For the same region children born in the months of the Pig, and Rat will have a significant difficulty in school, and in sports in their younger days.

Now it might sound like I just picked the strongest sounding Astrological signs, and the weakest. However, there is a very sound and logical reason behind my claims. If you want to see where the Chinese monthly Zodiac lands you can check out this link.

My opponent has a nice table, and claims that it shows no statistical significance. The problem with making any statistical claim about US presidents is usually that one lacks a sufficient sample size. There is a magic number that is the minimum that you want to have in an individual grouping, and that number is 30[1]. Unfortunately the way they've been grouped the largest group is only 17 for Libra, and that's with triple counting presidents. That chart can't be used to make much of any claim as it currently is. Berkley clearly would have had a problem doing any statistical analysis when the maximum sun signs is a total of 5 for Scorpio, and Aquarius. If Berkley didn't mention that there study was statistically invalid due to a small sample then they made a serious academic mistake, but since my opponents link to Berkley doesn't actually have anything to do with the astrological signs of Presidents I'll give them the benefit of the doubt. Maybe if they were divided based on equinox, and solstice you might get one statistically large enough to say something, but until you have 30 it's a bad idea to use the data to say anything for, or against. It's like the left handed president claim. It's a statistically invalid claim because it uses only 15 presidents and those are split nearly in half. It's impossible to say with a sample size of so few to claim anything.

As for my opponents claim that making predictions based on the observations is somehow wrong, or backwards I'd like to point out that is how science works. You make an observation like some people are better at spots. Then you make a prediction based on that observation like their birthday may have something to do with it. Then you test that prediction by surveying the population to see if your prediction pans out. It's also called the Scientific method: Observation, Hypothesis, Prediction, Experimentation, Conclusion [2]. It shouldn't be surprising that some still use the scientific method in astrology since astrology is one of the oldest sciences.

Debate Round No. 2


Brief Response to Pro's Round 2.
Pro does not seem to support Western Astrology, making my opening statements mostly a mute point. Thus, it can be ignored that Pro addressed the analysis on the presidents, but ignored the analysis on murderers.
Pro and I seem to agree on the scientific method, but Pro does not seem to understand my earlier statements in regards to the use of backwards reasoning. In the specific case given, the author of the article did not take predictions made by astrology and compare it to observations. Astrology doesn't simply predict that there will be differences among people with different zodiac signs. It gives more specific predictions in regards to life outcomes.

Brief Introduction to Chinese Astrology/Zodiac
For those unfamiliar, the Chinese Zodiac has 12 animal signs and 5 element signs, giving 60 possible combinations. Each year cycles through to a new element and a new animal. This 60 year cycle is linked to the 60 year orbit of Jupiter [1]. Chinese astrology makes specific claims in regards to what occupations are good for which animals [2].

Rebuttal to Chinese Astrology
Some animals are predicted to be good for politics, and others not. The best link I could find with a list of US Presidents and their Chinese Zodiac signs is given [3]. But if you would like to construct it for yourself, you can always do that by looking up their birthdays [4] and their animals using an easy calculator [5]. We find an almost even distribution among all the animals on the Chinese Zodiac. Because Chinese Astrology predicts that some animal signs would not do well in politics, I claim that Chinese Astrology does not make predictions that agree with reality. In this case, the sample size does not matter, because there was no statistical significance analysis.



I didn't really ignore my opponents murder sources. It's more that I expected him to realize that all 3 sources made the exact same mistake. The Analysis of the Presidents is invalid because you do not have enough of them to divide into groups of at least 30 for Zodiac analysis. Anyone attempting to do any statistical analysis claims on US presidents is going to have the same issue whether or not they're using Chinese, Mayan, or Western Astrology. There is just too few to make any claim for, or against. made the same mistake of only having a sample size of 77. Larger than the presidents, but only has one group that can be statistically analyzed in January. Without another group to compare it to the statistics will be invalid. does a bit of a better job, but you have to actually read their work. The first part you should pay attention to is under Test Parameters. It clearly states, "An individual group of this size is too small to run meaningful statistical tests." In other words they are openly admitting that there is going to be a problem with their results. Then under The Claim Being Made Under This Study it starts off stating "This is a work still in progress so no claim is being made (or can be made) as to whether or not there is any validity to astrology". In other words my opponents source is actually making no claim at all.

Honestly, I expected my opponent to take more than a few hours to respond. I've been caught at a moment with most of my sources being saved on a different machine. So I'll just have to reconstruct, and see if I can get remote access since I won't have direct access until after the time limit has lapsed.

Now lets examine my claim that kids at a particular time of year will be better at sports than other kids born at a different part of the year in the UK, and Europe. For this we'll be using the UEFA for their 2010 tournament, and European population data. The population data will consist of about 51 million samples for the population, and about 4 thousand players. What we expect if the date of ones birth has no effect on their participation is that if 8 percent of the population is born in January then only 8 percent will be playing the tournament. If it has an effect it will be significantly more or less. So what does this look like? Fortunately you can either do the work yourself, or look at this nice little chart that illustrates things nicely. You could also take the word of the reputable economists the wrote the book Freakonomics.

As you can see January, February, March, and a bit of April so a significant swing towards more players being born at those time periods which happen to be the Ox, Tiger, Rabbit, and Dragon signs in the Chinese Zodiac. The under performing months just happen to be the months that correspond to the Pig, and Rat. Otherwise known as November, and December.

That covers the bulk of my claim about performance in sports in one's youth. Pig, and Rat have an added penalty that they are actually more likely to be diagnosed with ADHD, and a slew of other psychological conditions[3].

Now to understand my claim of Baseball, or Football you have to understand that actual cause. This is actually the part where Astrology fails. It fails because it claims that the cause the Heavens, and the Earth. Where you're at in relation to a lay line, and which stars you're under when you're born. This is the part that cannot be tested because removing stars from the sky, and moving a lay line is impractical. However, this doesn't affect it's uses at predicting because the causes happen to be when and where you are born has a direct effect on who you'll be.

It's called the Relative Age Effect, and put bluntly the arbitrary dates we pick as cut off dates for school, and sports ends up having positive, and negative effects. Children born in January are a year older than their classmates born in December. They are given an advantage due to hitting puberty earlier, and then because they dominate their classmates they are given better encouragement, and coaching. The Relative Age Effect persists if the sport is like Baseball, but if it's a sport that relies on physical size that doesn't set in until after schooling like with the NFL then the advantage goes away[4].

It's not hard to see that we've been doing this for some time, and even though astrology is usually wrong about the cause it's predictive value isn't invalid.

Now look at the Ancient Mayan culture. A good portion of their astrology from the Dresden Codex is based on Venus. For them Venus symbolized good times, and war. For war it's a rather literal sign. You can tell a bunch of uneducated soldier to go to a city, and when they see Venus rise they should attack. Without any other form of communication you can have a nationwide simultaneous attack. The good times happen to be a result of the Post War Economic Boom and Bust cycle that occurs with war. If wars happen to occur on a periodic schedule they'll result in a predictable economic cycle as well.

My opponent is making a very bad assumption. He assumes that Astrology creates their charts, and predictions first. This is false. The charts come first to track time. Correlations are found in the population in relation to time, and those correlations become the predictions. Now some make the mistake of assuming correlation means causation, but I can't really fault Astrologers for that. After all it wasn't that long ago that Science made the claim that Ice Cream Kills Kids[5] because of the same kind of fallacy.

Debate Round No. 3


There are three major problems with Pro's argument relative to the definition Pro gave for Astrology in round 1.
"Astrology is any system that uses heavenly bodies in relation to ones birth to predict possible outcomes for an individual. Heavenly bodies are most commonly refereed to, but not limited to, the Earth, Sun, Moon, planets, and stars."

1) Fundamentals of the Chinese Zodiac are wrong
Pro asserts that different animals on the Chinese Zodiac are related to different months of the year. As I discussed in my previous round (see Brief Introduction to Chinese Astrology/Zodiac), the Chinese Zodiac assigns signs/animals based on what year a person is born. Every single link I gave in round 3 confirms this.

2) Not related to the position of heavenly bodies
Pro simply argued that the older children in the class will preform better than the younger children in the class. The age of a child in class is not entirely affected by the position of heavenly bodies relative to their birth. For example, a child may be held back a year or start school a year late. These children would be predicted to perform well regardless of the month they were born, because they would be older than their classmates.
There are other influences on possible outcomes other than the position of heavenly bodies. For example, domestic violence at home is likely to cause a child to perform worse than their peers at academics and social interactions [1]. This has no relationship to any heavenly body, including what time of year an individual is born.
Obviously, to make the predictions Pro claims, astrologers must know more than just the relationship of the heavenly bodies relative to ones birth. They must also know about the home environment, age cutoff for school, and other factors that influence child performance. Clearly, this does not meet the definition for Astrology that Pro gave in round 1.

3) Doesn't limit possible outcomes
Pro's argument asserts that an individual is more likely to succeed if born in a certain month. This prediction is too general. According to the sources I gave in round 3, Chinese Astrology attempts to predict what type of career is best for an individual, but Pro's form of prediction can't get close to attempting that. Pro gives two examples where the oldest kids in the class are expected to perform best at whatever it is they are doing, not one specific category. Because it is a statistical prediction, exceptions to the rule are acceptable. A child's performance does not always correlate to their age relative to their peers. So again, we end up with a scientific prediction, not an astrological prediction.

One closing note. The predictions that Pro has put forth are not made by any popular form of Astrology that I could find. Pro did not include one reference to a pro-Astrology source. If Pro is using Astrology, it appears to be so obscure as to not have a name. It is as if it is a form of Astrology that Pro invented in order to meet his own definition of Astrology, even though I have shown that Pro is using science, not Astrology.

Thanks for debating me, medv4380. Good luck in the future.



Many wise astrologers have a saying 'The stars impel; They do not compel.'[5] I wish I had the original source for it, but it's such an old, and common quote it's most likely lost to the flow of time.

Here are some reasons to vote Pro, and against Con.

Statistical Significance:

My opponent has made a few claims, but hasn't presented any statistically significant data to support his claim. Now if astrology made the claim that the predictions were absolute then maybe his flawed data would be valid. However, astrology, and myself, never made any absolute claim. When an astrology says that the stars impel they mean that there is a force persuading you to perform, or behave a particular way, but other influences in your life have impact as well.

The data that my opponent has presented is completely invalid. I warned him about the invalidity of such samples in hopes that he'd take some time, and find a sufficient sample. It's not as if a sufficient sample was outside of his grasp. There are too few US Presidents, but there is plenty of US Senators if you include the last 700 hundred.

What do we know anecdotal about the Senate? If it were me I would say that extremists have a harder time getting into the Senate than they do getting into the house. So which astrological sign is known for political extremism in Western Astrology? Since my opponent has such difficulty elsewhere. Aries would be a pretty safe bet.[6]

This took a while to put together since the only easy list of US Senators with birthday is only of the latest 100. Then Excel doesn't like dates earlier than 1900 so you have to do a bit of extra work to get a truly significant sample. I wasn't sure if I'd have the time to get enough of a dataset, but I was so I ended up with two charts.

The first is a chart of the probability of a US Senator being born 6 months from the starting month. The sample size is just over 700 so there isn't much doubt in what each chart shows. At least for the senators elected over the last 100 years.

The Second chart shows each month on its own. Most months have over 60 samples, and all of them exceed 30 which I stated was the minimum needed to even consider making a claim.

As you can see April, Aries, has an odd dip. Is the dip there because Spring makes people crazy as The Journal of Psychology suggested in 1997[7]. Is April just the latest date for a Relative Age Effect caused by the GOP and DNC conventions in June to August, and if so why is May unaffected? The correct answer requires a lot more data, and research. However, that doesn't discount the ability for Astrology to predict it. Only the ability for Astrology to claim the cause. There are statistical tests like a Box and Whiskers analysis[8] that will easily show that April is an outlier that should be looked at.

My claims have more significance than anything my opponent has presented, and what my opponent has presented as "significance" is little more than the significance found in the AntiVax data based off of only 12 cherry picked cases. Why he insisted on US Presidents despite it being statistically invalid is beyond me.

Accuracy of Facts:

I don't know why opponent is ignorant of Chinese Astrology, but he has no excuse given that I provided a perfectly valid link to explain things for him. I know most Westerners are ignorant of Chinese astrology having Monthly, Hourly signs, and many more. However, it's not that hard to look up, and since I provided a link explain as such he has no excuse.
So here's a few more links for him to educate himself.
or how about the wiki
"In fact, there are also animal signs assigned by month (called inner animals), by day (called true animals) and hours (called secret animals).'

If my opponent wants to debate astrology then the onus is on him to educate himself about the subject before to ensure a good debate. If he wants to claim that my knowledge of astrology is flawed them perhaps he shouldn't have exposed his complete ignorance of the subject that can be quickly, and easily confirmed with a search.

Reverse Causation:

Finally my opponent failed to respond to my claim with Mayan Astrology. What the Mayans clearly demonstrated was a case of reverse causation. Their belief in something actually caused the effect. Belief might sound insignificant, but it's actually why things like the placebo, and nocebo effect work. This ensures a level of predictability in Astrology as long as people use it.

I'd like to thank my opponent even though he should have taken more time to do some actual research on the subject.

Finally, thank you to the voters, and vote Pro.

Debate Round No. 4
11 comments have been posted on this debate. Showing 1 through 10 records.
Posted by Jellon 3 years ago
Sorry. Hope I didn't come across as yelling. Just trying to emphasize, and caps is the easiest way to do so. I welcome anyone to challenge me to have this debate. If anyone has evidence that any form of popular astrology can be proven correct, I would stand in wonder.
Posted by Jellon 3 years ago
I'm so confused right now. EVERYTHING I've read, including every link I gave to the Chinese zodiac and Wikipedia all claim that your animal corresponds to the YEAR you were born, NOT the MONTH. I explained that in my previous round. Please show me where you get your idea about the Chinese zodiac from.
Posted by Jellon 3 years ago
I don't expect a rebuttal in your first round. All yours. Good luck.
Posted by medv4380 3 years ago
No rush. I expect you to take what time you need for your argument. We should both have fun.
Posted by Jellon 3 years ago
Sorry I'm taking so long to reply. I'll have some free time tonight.
Good. I hope you do give a rebuttal. If you don't give a rebuttal until the last round, than you won't get a chance to give a response to my rebuttal. That's not fair to you.
I've never heard of that TV show. No I don't intend for this to be one sided, unless that's where the evidence points. I figured that anyone who took me up on this would be able to defend themselves; so, I assume it won't be one sided.
I wish you the best of luck. I hope you give me a challenge. I do these debates mostly to learn new things and have fun.
Posted by medv4380 3 years ago
There can be back and forth depending on what you give. This doesn't require an in-depth analysis. I only put up what I intend to do. I might have to do additional things depending on your claims.

If you want to understand the steph remark you'd have to watch No Game No Life episode 6 when steph becomes a description of games that are intended on being one sided. I take it that's why you thought no one would take it.
Posted by cheyennebodie 3 years ago
Some one asked me once, " what star were you born under". I said," all of them". They were all up there when I was born.
Posted by Jellon 3 years ago
Bit of a Steph or setup? :) no setup. I honestly didn't expect anyone to take this. Although I must admit, I am disappointed you make no plans to give a rebuttal until the last round. I was hoping for back and forth.
Posted by Envisage 3 years ago
I need to finish my book on Tarot Card reading first....
Posted by xXCryptoXx 3 years ago
Lol Astrology was a "science" that was abandoned during the scientific revolution of the 1500's-1600's
1 votes has been placed for this debate.
Vote Placed by whiteflame 3 years ago
Who won the debate:-Vote Checkmark
Reasons for voting decision: The main issue here, I think, was a disagreement in what Pro's burden was in this debate. Con tells me that burden is to prove that celestial bodies themselves can interfere with our lives, while Pro tells me that it's just a question of whether astrology makes accurate predictions, which may result from things independent of those celestial bodies. I buy Pro's analysis on this because that's what the resolution tells me. There's no reason why I have to also evaluate whether astrology comes to those conclusions based on celestial bodies or if it even happens by accident. Pro gives me a number of analyses that show that astrology can indeed predict many factors, and proceeds to show me how Con's predictions are meaningless based on statistical significance, which Con never responds to. Lacking a case study where astrology made an inaccurate prediction, on balance, it appears that astrology does make accurate predictions, and therefore I vote Pro.