Correlation, Causation: Potato, Tomato

The Ministry Of Silly Bikes Correlation is not causation. How many times have we heard that sentence? Too many times maybe, because we seem to be mithridatized by it. Nowadays, it seems like it’s nothing more than an easy way to discard inconvenient facts. It is true that correlation is not causation, but what does that mean?

Correlation is statistical interdependence. In other words, we talk of correlation when a class of events happens systematically together with another class of events. Correlation can be weak or strong, depending on the statistical strength of the relationship: the more it fails, the weakest the correlation.

Causation is a kind of correlation where one of the events is the cause of the other, which we call the effect. The cause always happens before the effect, but that’s not enough to prove causation. Proving causation is, in fact, tricky business if all you have is statistical data, and arguably that’s all you ever have..

What are the different reasons for correlation then?

First, it can be pure chance, which is something we’ll want to rule out. If you throw coins in the air with both hands and they land on the same side three times in a row, you can talk about correlation, albeit not a very strong one. The good thing is that this is fairly easy to eliminate: it is generally easy to see what results pure chance would give, and to compare that with a large number of events (even if homeopaths haven’t been able to figure it out). While it’s technically possible that freak statistical events happen, they are by definition improbable and a high degree of confidence can be reached that pure chance has been eliminated, by simply repeating the experiment a large number of times.

Second, there can be an underlying common cause. If waves reach both sides of a lake with a good phase correlation, it’s not necessarily that the waves on one side cause the waves on the other side. It’s more likely that the waves have a common cause, such as a rock being thrown into the lake. Experiments could be to create waves on one side and see if the same correlation can be produced, and then, to throw a rock and see what happens.

Third, it can be real, non-causal correlation. For example, the surface of a square is strictly correlated to the length of its sides: if the side doubles, the surface quadruples. The sides are not the cause of the surface any more than the surface is the cause of the sides. We just have two variables that are interdependent. They are correlated without causation.

And finally, correlation actually is, in many cases, the manifestation of a real causal relationship, in one direction or the other. Pushing an object causes it to accelerate, drinking battery acid causes death, smoking causes lung cancer, HPV causes cervical cancer, etc. All of these causal relationships were proven through some form of experimentation but it all starts with noticing correlation.

Next time you notice a correlation, don’t just dismiss it because “correlation is not causation”. Consider it instead as the first step towards discovery. Isolate variables, compare with chance, try to find underlying causes, determine if A causes B or B causes A, experiment. In other words, be scientific about it…


An example of a conflict between science teaching and religious beliefs

Wings In yesterday’s post, I explained how during my whole time as a physics student, I’ve never seen an example of a religious claim, positive or negative, creeping into the science teaching. It’s not that physical science is inconsequential to religious claims, it’s not. However, religion is off-topic in a science class, and there is only a conflict if someone brings religion into the classroom.

A religious student may feel his beliefs are threatened if the topic being exposed happens to be in conflict. It can happen in cosmology, but there’s probably no class where it will happen more than in biology. I didn’t study biology myself after high school, but I have lots of friends who did, and there’s one topic in there that I remember and that can’t leave any follower of an Abrahamic religion indifferent. That topic is the undirected nature of evolution, its total lack of an endgame.

This is of course not taught to annoy religious students, but because it’s extremely important in order to understand evolution. Also, it’s demonstrably true.

If there’s one thing that proponents of ID have understood, it’s that creation, old or young, makes predictions that are different from the predictions of evolution theory (too bad that they can’t recognize when their claims are falsified…). The prediction in this case is that if evolution was intentional, we would see mutations that would be temporarily deleterious, and that can only be explained because they are useful to an innovation that will appear many generations down. In other words, the mutations would not be selected out, because they will serve a role in the future.

Evolution theory predicts that this is very unlikely, because selection starts to exert its pressure as soon as the mutation appears. It turns out that there are no known examples of such mutations, and that every observation is consistent with the predictions of evolution theory.

In teaching those ideas, the biology teacher doesn’t have any intention to indoctrinate anyone: he’s just teaching the science. If there is a conflict, it has been deliberately brought in, and should be resolved outside of the science class.

This should clarify that conflicts do clearly exist between scientific and religious claims (and until now, science has been right every time there’s been a conflict). In the previous post, my goal was to show how there is no anti-theistic indoctrination in a science classroom because religious claims have no place there. In this post, I hope I’ve shown why the onus is on the religious student to take what he’s been taught in science class and resolve any conflicts outside, on his own or with his priest. If he’s intellectually honest and open-minded, some of his religious beliefs will have to be revised.


The terrible secular indoctrination machine

A UnicornHere’s a great example of projection: many members of the religious right in the US are convinced that non-religious universities are indoctrination centers for the far left and atheism. Case in point, my fellow blogger Ambrose writes:

The reason that higher education in the sciences and philosophy purportedly reduces religious belief has as much to do with contemporary popular antitheistic indoctrination in those fields as any supposed increase in knowledge, much less baseline intelligence.

The irony is quite strong, when the writer of such words got his entire education from Christian schools and universities.

I haven’t studied philosophy, however I can say a few things about science. I studied in France, but I’ve communicated, worked and studied with enough professors and students from many countries to know that what’s taught and how it’s taught is virtually identical everywhere.

Here’s how many times I remember hearing anything about, for, or against God, during my years studying, from first grade to my PhD: One. A student sneezed and my history teacher said: “que le bon Dieu vous patafiole”, which is a humorous and excessively fancy way of saying “God bless you”.

The truth of the matter is that religion is completely irrelevant to the teaching of science, and as such it is never mentioned. I have no idea which of my professors were religious. I know some of my friends were (I even once went on a retreat in a monastery with one of them), but they weren’t feeling indoctrinated, or they never expressed it. You’d need a particularly strong persecution complex to interpret that as “anti-theistic indoctrination”.

Funnily enough, my own atheism only became stronger and militant when I moved to the US. It’s not by any stretch of the imagination my professors who turned me against religion, it’s religious people, the grip they have on American public life, and their privilege. Religion is its own worst enemy, not science, not education. Unfortunately, some religious people are science and education’s worst enemies.


How scientific data gets distorted

The evil Aspartame molecule. Scary, eh?Here’s a good case study of how scientific information gets distorted. This article has sources, which is a little unusual (but they are not links, probably to discourage you from checking them out for yourself), but look at how they're used...

Here’s the conclusion of the first study:

"Although our findings preserve the possibility of a detrimental effect of a constituent of diet soda, such as aspartame, on select cancers, the inconsistent sex effects and occurrence of an apparent cancer risk in individuals who consume regular soda do not permit the ruling out of chance as an explanation."

In other words, inconclusive.

The second study is on rats and has significant results. It's a single study and not a meta-study:

The third one, well, there's no third one, it's the same link as the first one.

So what does the article say about these articles?

"a can of diet soda daily increases leukemia (cancer of the bone marrow, blood) in both men and women by 42%."

Well, that's a lie. Here's what the abstract really says:

"when sexes were analyzed separately with limited power, neither regular nor diet soda increased risk of leukemia but were associated with increased leukemia risk when data for men and women were combined (RR for consumption of ≥1 serving of diet soda/d when the 2 cohorts were pooled: 1.42; 95% CI: 1.00, 2.02)"

So it's very likely a statistical fluke: the data simply doesn't make sense, from the authors' own opinion. That even higher risks of cancer were found in men with regular sugar soda (that is ignored by MassReport) doesn’t improve the trust one can put in the results. Additionally, scientific results come with error bars (the CI interval that is in the complete abstract and that MassReports conveniently ignore), that make the results even more dubious. This is why the conclusion from the authors of the study are that it is inconclusive.

But wait, there's more: MassReports tells us

"What concerns us even more is how Aspartame is created. According to an article by The Independent, it has been confirmed by both a Monsanto spokesperson and a Monsanto source that the Aspartame creation involves genetically modified bacteria."

It concerns you even more than a risk of cancer that it's produced from GMOs? Why would that be? Could it be that you have no idea what you're talking about? It so happens that a very efficient way to produce simple organic molecules and proteins is to trick living organisms into doing the work, usually by manipulating their genome. There is no magical property that gets added to a molecule by the modified organism. The molecule is strictly indistinguishable from another copy that would have been obtained through more classical chemical synthesis. In fact, I suspect that the traditional chemical industry is way more harmful to the environment...

So what to make of that? Well, there's enough data on rats, and enough uncertainty on people to cast a sinister shadow on these products. I'm avoiding sodas myself (both sugar and sweetener-based), and prefer water and juice to them. That's an easy decision to make: water is, for sure, the best drink you can have health-wise. It is however a little too early for that class-action lawsuit against Coca-Cola. More science needs to be done...

The other obvious conclusion is that you should not take your science news from clickbait web sites. Always take the time to dig a little deeper and look at the actual research, it's usually more accessible than you think.


Infallible, part 3: the unoriginality and wrongness of Biblical creation

George Lemaître, le génie du ChristianismeIn my ongoing series of posts addressing the arguments from Michael, a militant Catholic, today’s post will examine the claim that the Bible’s cosmogony is unique among creation myths in that it talks about creation ex-nihilo. In Michael’s words:

Every culture known believed that the Earth, stars, indeed the entire universe has been present in all eternity. Creation stories abounded, but all the stories began with matter that preexisted

Of course, let’s get out of the way the fact that if that were true (it isn’t), it wouldn’t give any advantage to Catholicism against the rest of Christianity, against Judaism, or Islam, since all are sharing the same Genesis story.

It is also obvious that there is such variety in creation myths that it wouldn’t prove anything if one of them happened to correspond vaguely to reality. For instance, the Bhagavad Gita anticipates the concept of a multiverse, the expansion of the universe, until its thermal death, with time scales in the billions of years for the universe, and trillions of years for the multiverse. This is much closer to the current thinking in cosmology than Genesis ever was to the thinking of l’Abbé Lemaître last century. Does it prove that Krishna is the one true god? Of course not.

Let’s get back to Michael’s specific claims. Does every culture really believe that the universe has been existing for all eternity? Of course not. That claim alone betrays confirmation bias, and the thinking from someone who doesn’t bother to verify what other apologists have been saying. Other myths of creation ex-nihilo exist. Worse, Genesis does not itself appear out of thin air: it has its own influences and heritage in Mesopotamian mythology.

The biggest problem however is that Genesis is a primitive, vague creation myth that gets pretty much everything wrong: the Earth is created before the light, the firmament is a thing that is holding “waters”, plants appear before the night and day cycle, which appears before the Sun, which appears before the stars, the Moon appears only at night, and it goes on.

Even the claim of creation ex-nihilo is unsound: the relevant Hebrew verse would be more accurately translated as “in the beginning filled God the heavens and the Earth” (emphasis mine). This implies a pre-existing void that got filled, which is at odds with modern cosmology that shows that our space and time emerged at the Big-Bang, from nothing at all, from a singularity, or from another region of a multiverse. In any case, there was nothing to fill, as space itself had yet to be created.

There is nothing original in the Bible’s creation myth, and it is mostly wrong anyway. It cannot be seriously used as an argument to prove Christianity right.


The Kalām Cosmological Argument is a terrible argument – 1. Induction

Not the induction we're talking about here...It’s quite amazing how often the Kalām Cosmological Argument, or some version of it, is still used by believers to justify their faith. It seems like a naive understanding of modern cosmology, coupled with confirmation bias, conspire to keep this tired argument on life support. In this series of posts, my intention is to explain some of the ways in which KCA is a terrible argument, one problem at a time. In this first post, I’ll focus on whether it’s reasonable to apply inductive reasoning to the universe.

As a reminder, here’s how the KCA usually goes:

1. Everything that begins to exist has a cause
2. The universe began to exist
3. The universe has a cause

The first clause is an unjustified generalization that really is inductive reasoning in disguise. Inductive reasoning is a perfectly legitimate and inevitable way to reason –because it works– if you understand its limitations.

A more accurate version of the first clause could be:

Every thing that we’ve seen begin to exist has had a cause

I’ll address in a future post how even this formulation is false, but let’s focus on the induction issue for now. In this version, I removed the excessive generalization, thus pulling the induction from under the carpet and putting it in plain sight. I’ve also replaced “everything” with “every thing”. This is a really important nuance: in a similar way that “nothing” is not a thing, but is really “no thing”, the universe (i.e. the set of all the things that exist) cannot be treated like an ordinary thing. It’s in a category of its own. Inductive reasoning is the application of probability to a set of similar objects. It cannot, therefore, be applied to the universe, because there are no objects similar to the universe. And before you ask, yes, some physicists are guilty of doing exactly that.

And that is not even all that’s wrong with the first premise…


Time, causality, and prime movers

What's beyond the sky used to be a reasonable question.Sometimes we ask the wrong questions, and answer them with bad answers. One particularly bad question is: “what was there before the Big-Bang?” There are many others, but this one requires a little mental gymnastics in order to get used to modern ideas of time and understand what the consequences are.

“What was there before the Big-Bang” may have looked like a good question before Einstein (if anyone then had a clear idea of a universe expanding from a very dense original state, which they didn’t), but the revolution of Relativity in our concepts of time and space made it scientifically absurd. The word you have to remove from the question is “before”. Substitute “beyond”, and we have something to talk about, but “before” is just absurd in this context. Let me explain.

In a Newtonian, 19th century scientific framework, time and space are fundamental: physical phenomena, and the universe in general, happen in time and space, but time and space aren’t physical phenomena themselves. Einstein showed that time and space are not only relative, but are physical expressions of geometry. They are even in a way consequences of matter and energy. In other words, time and space are properties of the universe. They are of the universe, and don’t make sense outside of it (whatever “outside” could mean when talking about the universe).

As a consequence, time and space as we perceive them are not necessarily useful concepts “everywhere” (and I use that word with scare quotes to express an idea of a place that is more general than what we mean in everyday speech).

The Big-Bang is such a “place”: what scientists mean by Big-Bang is that early region in the universe where everything was so densely packed that our current knowledge of physics breaks down. It is where our ignorance begins, where taking our usual concepts of time and space seriously would lead to absurdities and infinities. The only certainty about what’s beyond the Big-Bang is that we need new science to understand and describe it.

Now if you care about metaphysical questions of origins, that leads to a serious problem: if there is no useful concept of time beyond the Big-Bang, do we still have a useful concept of causation?

Hume’s concept of causation cannot be kept in this context because it is based on time: the cause must be prior to the effect. If “prior” is meaningless, we are reduced to correlation, which can easily be reversed without contradictions.

The only causation that can be used here is the logical concept of necessary causes: if x must exist for y to exist, and y exists, then x exists. The first premise however is a tricky one…

Let’s take a favorite argument from theists, the Kalam cosmological argument. It starts with “everything that begins to exist has a cause”. There are too many problems in this statement to count, but the word we need to focus on is “begins”… The argument continues with “the universe began to exist”. We can stop right there: no, as far as we know, the universe didn’t “begin” to exist because that implies a meaningful notion of time, that we don’t have near the supposed origin of the universe. This argument simply doesn’t work.

I’ll leave you with a final puzzling thought about time and causality. Quantum physics introduced a funny notion that is that the results of some experiments cannot be predicted, and that we can only predict the probabilities of the possible outcomes. Without going into too much details, this doesn’t necessarily eliminate determinism at a fundamental level, but it does confirm that with our limited perception of time, the future is not fixed. One interpretation in particular, the Many Worlds Interpretation, sees us navigating in an infinitely branching network of possibilities. When an experiment is performed, other outcomes than the one measured may seem like they didn’t actualize, but according to Many Worlds, they did, it’s just that this is not where we are. Now here comes the crazy bit: in this interpretation, everything is still fundamentally reversible in time, and the branching that happens about the future also happens for the past. The consequence is that the past may be just as undetermined as the future is.

Have a nice day.


Discrimination by private businesses

Imperial Laundry Co. "We wash for white people only"I’ve been watching this video of Rachel Maddow interviewing Rand Paul about civil rights. Paul’s argument is that private businesses should be left free to discriminate, because Liberty. I think he’s profoundly wrong, here’s why.

Firstly, the argument that discrimination is a bad business decision is plain wrong. We may want it to be true, but there are places where it would actually be an excellent business decision. Just ask Chick-Fil-A.

Secondly, Paul repeatedly claims that racial segregation was a problem mostly in public institutions. While state discrimination was especially shocking, there is no shortage of legal cases showing that some business owners do shamelessly discriminate. To this day, ask any member of any minority, and they will tell you horror stories that happened to them personally, illustrating the reality of ordinary, everyday discrimination.

Thirdly, businesses have real power over people’s lives, a power that is highly asymmetrical. They can hire or fire, promote or demote, move abroad, destroy local economies, buy politicians, and they can refuse to provide their products and services. This great power however comes with very few counter-powers and responsibilities. As we’ve seen, public outrage does not constitute a credible deterrent for bigoted behavior, because there are more than enough bigoted customers to support bigoted businesses. If anything, those businesses are rewarded by the market. Additionally, if we were to listen to the likes of Rand Paul, the business world would be totally de-regulated. In his ideal, Libertarian word, the state is trivialized or non-existent, and as a consequence, the real power lies within the corporations, unchallenged, and free to discriminate. No, thanks.

“We reserve the right to refuse service to anyone.” Who do you think they mean?


Cartoon history

Giordano BrunoThe Christian blogs these days seem to be erupting with outrage over a short cartoon sequence in the new Cosmos TV show. The segment in question tells the story of Giordano Bruno, and it’s… well, cartoony, both literally and figuratively. That’s not shocking on its own, the science itself in Cosmos is cartoony: biologists will cringe at inaccurate representations of a DNA molecule, astronomers will face palm when Tyson’s spaceship avoids planetoids that are in reality many orders of magnitude farther away from one another. It’s the nature of the exercise: trying to convey complex ideas to an uninitiated public in simple and entertaining images, will require simplifications, dramatization, shortcuts, and even that you’ll occasionally be plain wrong. Being a science show, maybe it was sloppier and more caricature on the history. I don’t know, I’m no historian. As long as deception is not deliberate and central to the discourse…

The blogs do claim that deception there is, however, and proceed to plead for the Church:

“it was Bruno's theological beliefs, rather than his beliefs about the universe, that were troubling to the inquisitors in Rome.”

Of course, this is missing the point by several light years. It doesn’t matter what ideas got Bruno to be burned at the stake. It matters that the Church was getting people tortured and executed for thought crimes. This is why mankind had to free itself from the oppression of religion and establish freedom of thought as a sacred value, in order to enable the explosive progress of science, literature, philosophy, education, and individual rights that it has been enjoying for centuries now.