Assumptions vs. inductive logic: is radiometric dating based on assumptions?

Posted on June 18, 2015 by Fallacy Man

Anyone who has tried to debate a creationist has invariably encountered their liberal use of the word, “assumption.” This is one of their trump-card, catch-all arguments that they use to handily “defeat” any evidence that opposes their position. For example, if you present them with the fact that coral reefs grow much too slowly to have formed in the past 4,500 years (their calculated time since the supposed world-wide flood), they will say, “well, you’re assuming that corals couldn’t grow faster in the past.” Similarly, if you point out that ice cores clearly show that the earth cannot possibly be less than 10,000 years old, they will retort, “well you’re assuming that layers only form annually.” Most infamously, when faced with the realization that radiometric dating completely obliterates the notion of a young earth, they choose to ignore that evidence because scientists are, “assuming a constant rate of decay/the amount of material in the original rock.” These blind dismissals of evidence are often accompanied by a rhetorical, “were you there?” The problem is that creationists are misusing the term “assumption,” and, as usual, are completely misconstruing how science actually works. As I will demonstrate, coral growth rates, radioactive decay rates, etc. are not assumptions. Rather, they are the conclusions of simple inductive logic.

The definition of “assumption”
First, we have to define “assumption.” At the broadest level, you could define an assumption as something that cannot be proved with 100% certainty, but that is an extremely problematic definition because it makes virtually everything an assumption. This is the problem that Descartes was describing when he famously proclaimed, “cogito ergo sum” (I think therefore I am). You see, I cannot prove with 100% certainty that I am not currently dreaming, or that we are not currently in the Matrix. The only thing that I can be 100% certain of is my own existence. Thus, at this broad definition, I am “assuming” that I am actually in a real, physical universe. Fortunately, I think that even creationists would agree with me that this definition is not really useful, and I don’t think that it is the definition that they are operating under.

A more restrictive definition is that an assumption is something that was not directly observed. Indeed, this seems to be the definition that creationists use, but this definition is also fraught with problems and inconsistencies. The most fundamental problem is one which I have previously elaborated on. Namely, direct observation is actually very unreliable, and you can use simple inductive logic to reach conclusions about something without directly observing it (i.e., there is no difference between “historical” and “observational” science). Remember that inductive logic is the type of logic that goes from a series of observations to a general conclusion.

I have used the theory of gravity to illustrate this before, but it is such a good, clean example that I am going to use it again. The theory of universal gravity states that all objects with mass produce gravity and are acted on by the gravity from other bodies. It also goes on to detail the math of how these bodies interact with each other, ultimately producing what is known as the gravitational constant (G) where G = 6.672×10^-11N m^2 kg^-2. This value is exceedingly useful and lets us do something really neat. For any two bodies, if we know the mass of each object and the distance between them, then we can use G to calculate the force of gravity between those two objects. These calculations will, however, only work if G is actually constant.

The question is, of course, how do we know that the gravitational constant is in fact constant? Well, quite simply, we have tested it over and over again and it has always been correct. In other words, we accept it as true because of inductive logic (i.e., we went from a series of observations to a general conclusion). Importantly, we can never prove that G actually is a constant, because doing that would require us to test G against every single piece of matter in the universe. That’s clearly impossible, so instead we rely on inductive logic (also there are very strong mathematical reasons to think that G is constant).

This is where things get interesting (and problematic for creationists). We use G all the time, even in situations where we can’t actually observe it to confirm that G works for the object in question. Any high school level physics course will go over calculations that use G, and it is extremely important for astrophysics. This is important because no one would claim that G is just an “assumption,” but that is exactly what creationists’ definition of assumption does. Imagine for a moment that an astrophysicist derived an explanation for some phenomena, and the math for that explanation involved G. It would be utterly absurd for you to say, “I don’t have to accept that explanation because you are assuming that G is constant.” We know that G is constant because we have measured it over and over again and it has always been constant. Therefore, via inductive logic, we must accept that it is constant until we have been shown a compelling reason to think that it is not constant. Even so, we have measured the rates of radiometric decay over and over again and they have always been constant. Therefore, via inductive logic, we must accept that they are constant until we have been shown a compelling reason to think that they are not constant. Similarly, we have repeatedly measured coral growth rates, and we know that even their fastest growth rate is nowhere near fast enough for them to have formed in only a few thousand years. When we make a statement like that, we aren’t “assuming” that growth rates weren’t faster in the past; rather we are applying inductive logic.

Also, note that the argument that creationists are making here is nothing more than an ad hoc fallacy. There is absolutely no reason to think that coral reefs grew faster in the past, or ice cores and varves formed multiple layers annually, or radioactive particles decayed faster, etc., but creationists are assuming that those things occurred even though there is absolutely no evidence to support those notions. That is the proper use of “assumption.” An assumption is something which you choose to accept as true despite a lack of supporting evidence. So, despite what creationists would like you to believe, scientist’s methods for dating the earth are based on inductive logic, not assumptions; whereas creationists’ arguments are based entirely on assumptions and ad hoc fallacies (note: I am using “assumption” synonymously with “unfounded assumption” because that is the way in which creationists seem to use it).

How radiometric dating actually works
Hopefully at this point you realize that scientists aren’t just making haphazard assumptions, but just to be sure, I want to quickly walk through how radiometric dating actually works because there is a lot of confusion and misinformation about it. First, realize that there are many different types of radiometric dating. Each method is specific to the type of rock that it can date, and which one you use depends on what type of material you are working with (on a side note, you may see creationists claim that they have dated something that we know is recent, such as a rock from Mt St. Helen, and the radiometric dating said it was old. These reports are generally a result of creationists using the wrong method for the rock in question).

To illustrate how radiometric dating works, I am going to focus on one method (uranium-lead dating), but all other types of radiometric dating follow the same general steps (note: technically there are two types of uranium-lead dating and both are generally used simultaneously, but I am going to focus on the cycle of 235U to keep things simple). Uranium-lead dating is used on a type of rock known as a zircon. Zircons are useful because when they form, the formation process incorporates uranium, but it strongly repels lead, which means that a newly formed zircon will never have any lead in it. This resolves creationists’ claim that scientists “assume the amount that was in the rock to begin with.” We aren’t “assuming,” rather we have tested the formation processes of zircons, and we understand the chemistry, and we know that lead simply isn’t incorporated. That’s simple inductive logic (note: the amount of uranium in the parent rock is irrelevant).

Uranium exists in several isotopes (same element, different numbers of neutrons), and the one we are interested in is 235U. 235U decays into 207Pb (an isotope of lead) at a rate known as a half-life. A half-life is the amount of time that it takes for half the atoms to decay. For 235U, a half-life is roughly 704 million years. How do we know what the half-life is? Simple: we have measured the rate of decay over and over again and it has always been the same (i.e., inductive logic). Also, as with the theory of gravity, there are strong mathematical reasons for thinking that the rate is constant (in fact, it’s a scientific law known as the law of radioactive decay). So, once again, saying that scientists “assume” that decay rates are constant is no different from saying that scientists “assume” that gravity is constant. Saying that we shouldn’t trust decay rates is just as absurd as saying that we shouldn’t trust gravity.

To illustrate how a half-life works, let’s say we have a rock that starts off with 80 atoms of 235U. After 704 million years, it will have a 1:1 ratio (40 atoms of 235U and 40 atoms of 207Pb) because half of the particles will have decayed. After another 704 million years (1,408 million total), the ratio will be 1:3 (20 atoms of 235U and 60 atoms of 207Pb). After 704 million more years (2,112 million total), the ratio will be 1:7 (10 atoms of 235U and 70 atoms of 207Pb), etc. The ratios are the important things here, and they are why the amount of uranium in the original rock is irrelevant. We can take a zircon, measure the amount of 235U and the amount of 207Pb, and the ratio of those two chemicals will tell us how old the rock is. For example, if the ratio is 1:7, then we know that it is 2.1 billion years old. It doesn’t matter if that ratio is from 1 atom of 235U and 7 atoms of 207Pb or from 1,000 atoms of 235U and 7,000 atoms of 207Pb, the ratio is still 1:7.

In summary, radiometric dating is based on well tested, scientific results, not assumptions. We know that there was no lead in zircons to begin with, because zircons strongly repel lead when they are forming. That is not an “assumption,” that is an inductive conclusion based on multiple experiments. We don’t know how much uranium was present in the original rock, but we don’t need to because the ratios are all that we care about. Finally, we know the rate at which uranium decays into lead because we have repeatedly measured it, and it has always been the same. So you see, when creationists claim that radiometric dating relies on “assumptions” they are grossly mischaracterizing how the process works, and they have demonstrated that they are either dishonest or ignorant about the science. Either way, they aren’t a trustworthy source of information.

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5 simple chemistry facts that everyone should understand before talking about science

Posted on May 27, 2015 by Fallacy Man

One of the most ludicrous things about the anti-science movement is the enormous number of arguments that are based on a lack of knowledge about high school level chemistry. These chemistry facts are so elementary and fundamental to science that the anti-scientists’ positions can only be described as willful ignorance, and these arguments once again demonstrate that despite all of the claims of being “informed free-thinkers,” anti-scientists are nothing more than uninformed (or misinformed) science deniers. Therefore, in this post I am going to explain five rudimentary facts about chemistry that you must grasp before you are even remotely qualified to make an informed decision about medicines, vaccines, food, etc.

 

1). Everything is made of chemicals

This seems like a simple concept, but many people seem to struggle greatly with it, so let’s get this straight: all matter is made of chemicals (excluding subatomic particles). You consist entirely of chemicals. All food (even organic food) consists entirely of chemicals. Herbal remedies consist entirely of chemicals, etc. So, when someone says something like, “I don’t vaccinate because I don’t want my child to be injected with chemicals,” they have just demonstrated how truly uninformed they are, and you can be absolutely certain that they don’t know what they are talking about because all matter is made of chemicals.

A “chemical-free lifestyle” is totally impossible. You can only survive without chemicals for 1-2 minutes, after that you will suffocate from a lack of oxygen. Right now, you are breathing in dioxide (aka oxygen) and your body is using that chemical as an electron acceptor for a process known as cellular respiration. This process takes carbohydrates such as glucose (which is a chemical) from your food, and breaks those carbohydrates down in order to release carbon dioxide (a chemical), water (also a chemical), and energy stored in adenosine triphosphate (ATP) molecules (still chemicals), and it is ATP which fuels your entire body. This process also involves numerous enzymes and electron acceptors such as acetyl coenzyme A and nicotine adenine dinucleotide (NADH), all of which are chemicals. Are you getting the picture here? You are a biochemical machine and every single thing that you do is driven by chemical reactions inside of your body. Even just reading this post is causing various chemical reactions inside your nervous system which are allowing you to process information. So there is no inherent reason to fear chemicals. You and everything else on this planet are made of chemicals and you would quickly die without them.

It’s also worth noting that the length of a chemical’s name does not indicate how toxic it is. The internet is full of scare tactics and fear-mongering over chemicals with long scary- sounding names. For example, Vani Hari (a.k.a. the Food Babe) is famous for proclaiming that you shouldn’t eat anything that you can’t pronounce or spell. This is patently absurd. For example, consider the following chemicals: retinal, cyanocobalamin, ascorbic acid, and cholecalciferol. Having taught college biology and listened to my students butcher scientific words, I am confident in saying that a large number of people would struggle to pronounce those, and many of them would likely freak out over things like ascorbic acid which sound like they should be bad for you. In reality, those are simply the chemical names for vitamins A, B, C, and D. Similarly, all living things contain DNA, and as a result, virtually all food contains DNA, but DNA stands for deoxyribonucleic acid. Again, its a long, difficult to pronounce name, and it sounds bad because it’s an acid, but it is essential for life and it is in nearly all foods. It is naive and childish to base your diet or medical practices on your pronunciation skills.

 

2). The dose makes the poison

There is no such thing as a toxic chemical, there are only toxic doses. Let me say that again: essentially all chemicals are safe at a low enough dose, and essentially all chemicals are toxic at a high enough dose. This is a fundamental fact that people in the anti-science movement routinely ignore. Vani Hari is notorious for rejecting this fact by making claims such as, “there is just no acceptable level of any chemical to ingest, ever.” The reality is quite different. For example, everyone reading this currently has mercury, arsenic, cyanide, formaldehyde, aluminum, lead, and a host of other “toxic” chemicals in your body right now. Further, you would have those chemicals even if you had spent your entire life hundreds of miles from anyone else, ate only organic food that you grew yourself, never used pharmaceuticals or vaccines, etc. These are chemicals that are normally in our environment and we acquire them through our food, water, etc. Some of these (such as formaldehyde) are even produced by our bodies. Even radioactive chemicals like uranium are often present. So clearly there are safe levels of “toxic” chemicals since all of us normally have them in our bodies. Inversely, “safe” chemicals such as water are toxic in high enough doses. People have, in fact, overdosed on water. To be clear, they did not drown, they overdosed. Water is actually dangerous to your body at high enough levels.

The importance of this fact cannot be overstated. No chemical is inherently safe or inherently dangerous. So, the next time that someone tries to scare you about the “toxic chemicals” in your food, medicine, vaccines, detergents, etc. ask them for two pieces of information:

  1. What is the toxic dose in humans?
  2. What is the dose in the product in question?

Those two pieces of information are absolutely crucial for evaluating the safety of the product. You simply cannot know whether that chemical is dangerous without knowing the dose in the product and the dose at which it becomes toxic. So, if your friend, blogger, etc. cannot answer those two questions, then they have just unequivocally demonstrated that they haven’t done their homework and don’t know what they are talking about; therefore, you shouldn’t listen to them. Indeed, a great many anti-science arguments crumble under the realization that the dose makes the poison. For example, we have all no doubt heard people rant about the “toxins” in vaccines, but the reality is that the supposedly toxic chemicals in vaccines are present in completely safe doses and, therefore, are totally safe.

 

 3). There is no difference between “natural” and “synthetic” versions of a chemical

I often hear people claim that “synthetic” chemicals (a.k.a. chemicals made in a lab) are not as good for you as their “natural” counterparts. The reality is that this represents a misunderstanding of literally the most fundamental concept of chemistry. The most basic unit of matter is the atom (again, excluding subatomic particles), and there are several different types of atoms known as elements. We combine these elements to make various molecules, and the combination of elements determines the molecule’s properties. The process by which those elements were combined is completely and totally irrelevant to how the final chemical behaves.

For example, water (a.k.a. dihydrogen monoxide) consists of three atoms: 2 hydrogens and 1 oxygen (hydrogen and oxygen are both elements). There are literally thousands of different chemical reactions that will produce water. In other words, we can make water thousands of different ways, but water always behaves in exactly the same way no matter how it was formed because it always consists of the same three atoms. Further, if given a vial of pure water, there isn’t a chemist anywhere in the world who could tell you how that water was produced because it would be completely identical to all of the other water everywhere on the planet. So, as long as the chemical structure is the same, it doesn’t matter if the chemical was extracted from a plant or synthesized in a lab.

 

4). “Natural” chemicals are not automatically good and “artificial” chemicals are not automatically bad

I often encounter people who will claim to agree with everything that I have said thus far, but they still insist that “artificial” chemicals (a.k.a. chemicals that simply are not found in nature) are bad for you and shouldn’t be consumed, injected, etc. There are several critical problems here. First, remember again that esentially all chemicals are dangerous at a high enough doses and safe at a low enough dose. That is just as true for artificial chemicals as it is for natural chemicals. Second, this claim is nothing more than an appeal to nature fallacy. Nature is full of chemicals such as cyanide and arsenic that are dangerous at anything but a very low dose, so there is no reason to think that the “naturalness” of a chemical is an indicator of its healthiness.

Further, remember that chemicals are nothing more than arrangements of elements. There is absolutely no reason to think that nature has produced all of the best arrangements or that we are incapable of making an arrangement that is safe or even better than what nature produced. I constantly hear people say that we cannot improve on nature, but that is an utterly ludicrous and unsupportable claim, and I would challenge anyone to give me a logical syllogism that backs it up. Really think about this for a minute, if you are of the opinion that artificial chemicals should be avoided, try to defend that position. Ask yourself why you think that. Can you give me any reason to think that they are bad other than simply that they aren’t natural (which we have just established is a fallacy)?

 

5). A chemical’s properties are determined by the other chemicals that it is bound to

Chemical compounds are made by combining different elements or even molecules, and the final product may not behave the same way as all of its individual parts. Sodium chloride is a classic example of this concept. Sodium is extremely reactive and will literally explode if it contacts water, and chlorine is very toxic at anything but an extremely low dose. Nevertheless, when we combine them we get sodium chloride, which is better known as table salt. Notice that table salt does not have the properties of either sodium or chlorine. It does not explode when it contacts water and you cannot get chlorine poisoning from it no matter how much of it you eat. The combination of those two elements changed their properties and it would be absurd to say that “salt is dangerous because it contains sodium.” The sodium in salt no longer behaves like sodium because it is bound to the chlorine. Therefore, when you hear a claim that something contains a dangerous chemical, make sure that the chemical isn’t bound to something that makes it safe.

Thimerosal in vaccines makes an excellent illustration of how little anti-scientists actually understand about chemistry. You have no doubt heard that vaccines are dangerous because they contain mercury, and mercury is toxic. Ignoring the fact that currently only certain types of flu vaccines contain mercury and the fact the mercury is present in very low doses, there is another serious problem here. The mercury in vaccines is in a form known as thimerosal. Thimerosal is mercury bound to an ethyl group, making it ethyl mercury. The mercury that causes poisoning (i.e., the form that accumulates in seafood) is mercury bound to a methyl group (a.k.a. methyl mercury). Ethyl and methyl mercury are not the same thing. They do not behave the same way. Just as the properties of the sodium were changed by the chlorine, the properties of the mercury are changed by the ethyl group. So, claiming that “mercury is dangerous and vaccines contain mercury, therefore vaccines are dangerous” is no different from claiming that “sodium is dangerous and salt contains sodium, therefore salt is dangerous.”

 

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Vaccines don’t give lifelong immunity, but they are still better than natural immunity

Posted on May 10, 2015 by Fallacy Man

Anyone who has spent time talking to anti-vaxxers has probably encountered the argument that we shouldn’t vaccinate because vaccines only provide temporary immunity whereas natural immunity is lifelong. This is one of the most insipid, infuriating, irrational and easily defeated claims of the anti-vaccine movement. Nevertheless, like the mighty Hydra it continues to resurrect itself and pervade the internet. I’ve dealt with this argument briefly before, but lately I have been seeing it rather frequently, so I have decided to devote an entire post to explaining why this argument makes no sense whatsoever.

Does natural immunity last longer than artificial immunity?
I want to begin by briefly looking at the facts to see whether or not the fundamental claim of this argument is even true. When you look at the research on vaccines, you quickly find that this claim is only partially true. There have admittedly been several studies that have documented that immunity from vaccines does not last as long as naturally acquired immunity. This actually makes good sense. The whole point of a vaccine is to trigger an immune response without actually inflicting the patient with the disease itself. The mechanism through which the immune response is triggered is the same with vaccines and with natural immunity, but the magnitude of the response differs, and it is hardly surprising that your body would keep a higher level of active anti-bodies after a full infection than it would after the small antigen exposure that it receives from a vaccine.

So there is some truth to this claim, but anti-vaxxers grossly exaggerate it and misrepresent the facts. For example, a study comparing the immune responses of people who were vaccinated against measles with the immune responses of people who actually had a measles infection found almost no difference between the two groups after 21 years. Further, the claim that natural immunity is lifelong is often erroneous. For example, a review of the literature on pertussis (whooping cough) found that immunity from vaccines typically lasted 4–12 years and natural immunity lasted 4–20 years. So the natural immunity lasted longer, but it was by no means “lifelong.” To be naturally immune for life, you’re going to have to get multiple pertussis infections, which kind of defeats the point of being immune.

To summarize, if you’re claiming that vaccine-induce immunity is temporary but natural immunity is lifelong, then you are simply incorrect. Your premise is demonstrably false. If, however, you are claiming that both types of immunity are temporary, but natural immunity typically lasts a little bit longer, then your premises are technically correct, but, as I’ll explain below, your argument still suffers from very serious logical problems.

Who cares if natural immunity lasts longer?
There are numerous logical problems with the argument that natural immunity is somehow better than artificial immunity. First, this argument often boils down to nothing more than an appeal to nature fallacy. Many people that I talk to think that natural immunity is better simply because its natural, but that’s clearly absurd. Death from measles is totally natural, but no one thinks that it is better than living a long, healthy, measles-free life.

Other people seem to simply think that the fact that natural immunity lasts longer automatically makes it better. This is, however, one of the most mind-bogglingly stupid notions that I have ever encountered. Here’s the important thing about natural immunity: to get it, you have to get the disease! There is no universe is which it is better to get the disease so that you are protected from future infections for longer rather than simply avoiding getting the disease in the first place! Let’s use the pertussis example from above. You have two options:

  1. Get pertussis, which will make you immune for up to 20 years, at which point you will need a new infection if you want to continue being immune
  2. Get a vaccine, which will make you immune for up to 12 years, at which point you will need a booster if you want to continue being immune

The second choice obviously makes more sense because it avoids you ever getting pertussis, but this inane anti-vax argument claims that option one is actually better, because after getting infected you’ll be protected for 20 years, whereas the vaccine will only protect you for twelve. How anti-vaccers can ignore the fact that the vaccine prevents you from getting the disease in the first place is totally beyond me.

As many others before me have pointed out, if we applied this twisted logic to other areas, we would get all sorts of bizarre conclusions. For example, no birth control method is 100% effective at preventing pregnancy, but it is impossible to get a new pregnancy if you are already pregnant (excluding a few extremely rare medical conditions). Therefore, according to the logic of this anti-vax argument, if you want to avoid a pregnancy, you should get pregnant, that way you can have sex without worrying about getting pregnant. That really is what this argument claims. It proposes that you should get a disease that way you won’t get the disease again. Surely, it would be better to simply avoid getting the disease in the first place!

This brings me to what is perhaps the most important point of this post: regardless of how long the immunity lasts, your odds of getting a disease are much lower if you are vaccinated. This fact is simply not up for debate. It is demonstrably and quantitatively true. Take a look at the data for pertussis, measles, mumps, and rubella from Schmitz et al. 2011 (below). Look at the measles outbreak in France where the vast majority of patients (roughly 80%) were unvaccianted, even though less than 20% of the population was unvaccianted (in many cases much less, depending on the age group). Examine the measles outbreak in the Netherlands where 96.5% of victims were unvaccinated. Look at the data from Bangladesh where death rates from measles were 46% lower among vaccinated children. Think about that for a second, who gives a crap about which type of immunity lasts longer when vaccinated kids are dying 46% less frequently than unvaccinated children? It doesn’t matter if natural immunity lasts longer because natural immunity requires you to actually get the disease. The best option is clearly the one that minimizes your chances of ever getting the infection in the first place.

Effectiveness of vaccines against pertussis, measles, mumps, rubella

Disease rates are much higher among the unvaccinated than among the vaccinated. Figure from Schmitz et al. 2011.

Boosters aren’t a big deal
Closely related to (and often associated with) the argument that vaccines don’t provide lifelong immunity is the argument that vaccines aren’t effective because they often require boosters. I often hear anti-vaccers touting this fact as if it is a death blow to vaccines, but the logic here is seriously flawed. First, remember that natural immunity often isn’t lifelong either. Second, who cares if you have to get a booster? This argument claims the following: “vaccines aren’t perfect and require follow-ups, therefore they are worthless and we shouldn’t use them.” That makes absolutely no sense whatsoever. Getting a booster is not a big deal. Once every twelve years or so you take a few hours out of your day to go to a doctor, pay him/her a few bucks, and suddenly you are protected for another 12 years. I fail to see how that is a critical problem that somehow undermines the effectiveness of vaccines and supersedes the massive reductions in disease rates that are associated with them.

To really drive this point home, let’s apply anti-vaccer’s logic to other areas of life. If this argument worked, then you also shouldn’t change your car’s oil, because you’re just going to have to change it again in a few months. Similarly, you shouldn’t replace your carpet, because the new carpet won’t last forever. Further, why should you clean your gutter when you’re just going to have to clean it again next year? Hopefully you see the point here: the fact that something isn’t permanent doesn’t make it worthless.

Finally, I want to bring my fundamental point back into focus. Yes, vaccines only protect you for a limited number of years, but not getting vaccinated protects you for exactly zero years. You have no protection until you get infected. So if my options are: be protected from the disease (with the caveat that I need periodic boosters) or simply don’t get any protection at all until after I’ve already gotten the disease! I’m going to take the former option. Any rational person would take the former option. The latter option is bordering on the definition of insanity. Getting a disease in order to be protected from the disease is mind-numbingly idiotic.

It’s about more than just the duration of protection
As I’ve already explained, your odds of ever getting an infectious disease are much, much lower if you have been vaccinated against that disease, but there is a lot more going on than just your personal protection. First, we also have to consider herd immunity. When most of the people in a population have been vaccinated, then it is very difficult for a disease to spread through the community because the vaccinated people shield the unvaccinated people. Anti-vaccers really don’t like this fact, and they often completely deny the existence of herd immunity, but it is a simple mathematical concept that is easy to simulate (you can also check out this neat simulator that lets you simulate outbreaks in actual US cities). Further, this is not just a hypothetical concept, we have experimentally demonstrated that herd immunity does in fact work (Rudenko et al. 1993; Hurwitz et al. 2000; Reichert et al. 2001; Ramsay et al. 2003). The exact methods vary among studies, but the basic idea is that you vaccinate a subset of a community, then monitor the disease rates in the unvaccinated portion of the community (preferably with a control community that received no vaccines at all).

For example, one of the earliest studies did this by taking two towns and vaccinating 85% of the schoolchildren in one town but not the other. What they found was that in the town with the vaccinated children, the disease rate was lower not just for the children, but also for the adults (compared to the adults in the town with no vaccines). This is herd immunity at work. By protecting the children, the adults were also protected because the disease could not spread as easily.

My point is that vaccine-induced immunity is better than natural immunity because getting natural immunity requires you to get the disease which makes you a vector that can spread the disease to others. In contrast, when a large portion of the community is vaccinated, there are very few vectors and large outbreaks are prevented. This is a very important benefit of vaccines.

Another consideration is the fact that vaccines not only protect against a disease, but they often reduce the severity of the disease. The pertussis vaccine is a great example of this. Not only are your odds of getting an infection much lower with the vaccine, but if you get the disease, it will generally be more mild if you had a vaccine.

It is also important to remember that diseases often come with additional complications. For example, in the process of acquiring natural immunity to measles (i.e., you get a measles infection) 1 out of every 10 children will get an ear infection (which can lead to permanent deafness), 1 out of every 20 will get pneumonia, 1 out of every 1,000 will get encephalitis (swelling of the brain), and 1 out of every 1,000 will die (numbers are from the CDC). Further, encephalitis can lead to permanent brain damage (that’s a pretty high price to pay for natural immunity). The influenza vaccine is another good example of this. A study that looked at the secondary effects of the influenza vaccine in the elderly found that it resulted in a 19% reduction in the risk of hospitalization for cardiac disease, 16–23% reduction for cerebrovascular disease, and a 48–50% reduction for the risk of death. Those are hard facts that natural immunity simply cannot compete with.

Artificial immunity is demonstrably better than getting natural immunity
Finally, just in case you haven’t been convinced by the mountain of evidence that I have prevented thus far, I want to discuss a recent study that is extremely damning to the idea that natural immunity is better than artificial immunity. As it turns out, a measles infection has a rather fascinating effect on your immune system. It does indeed give you immunity to future measles infections (at least for a few years), but it also suppresses your immune system and even “erases” your immunity to other diseases. The researchers found that people who had measles infections experienced a reduced immune response for 2–3 years after the infection. This results in increased rates of secondary infections (which can at times leads to death) during that period. In other words, obtaining natural immunity is bad for you, because even if you don’t get pneumonia or one of the other complications of measles, you have just weakened your immune system for the next 2–3 years! So the cost of natural immunity to measles is three years of a reduced immune response to other diseases. There is no universe in which that is better than simply getting a vaccine and avoiding the infection in the first place.

Summary
In conclusion, neither natural or artificial immunity provides life-long protection. Natural immunity does often last a few years longer than artificial immunity, but it requires you to actually get the disease in the first place, and that initial infection can adversely affect your immune system for several years. Further, even with a shorter duration of immunity, vaccines greatly reduce your risk of ever getting the disease, which in turn greatly reduces your risk of getting any of the complications and secondary infections associated with the disease, and when most people vaccinate, herd immunity is built up and everyone enjoys a lower disease rate (even the anti-vaccers). So, the argument that natural immunity is better than artificial immunity makes no sense whatsoever. It is demonstrably better to get artificial immunity through a vaccine than it is to get natural immunity through an infection.

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Falling branches: the illusion of miraculous divine intervention

Posted on May 1, 2015 by Fallacy Man

Human beings like to have explanations for everything, and we find seemingly inexplicable events extremely troubling. We disdain the notion that some things just happen without any rhyme or reason for them. This dependency on meaningful events makes us prone to contriving and accepting supernatural explanations even though science offers us explanations that are more satisfactory (although often less comforting). I am, of course, talking about our tendency to claim that an event was a miracle. When an improbable event occurs, such as a “miraculous” recovery from cancer, people of many different faiths and religions are quick to claim that the recovery was a result of some form of supernatural intervention, rather than merely a product of statistical probability. That should not, however, be our default. Any time that science offers an explanation, we should default to it rather than proposing a divine plan that is being supernaturally orchestrated.

miracles

 

To be clear, I am not trying to convince anyone that God doesn’t exist, or even that there is no such thing as the supernatural. The existence of supernatural beings is a question that science is completely and totally incapable of addressing. It’s the realm of philosophy and theology, not science. So it doesn’t bother me if people are religious and find comfort in believing in a supernatural deity. What bothers me is when people allow their spirituality to trump science and logic. That’s what I take issue with, and that’s what I am going to address in this post.

Falling branches
Several years ago, there was a large storm that knocked over numerous trees and caused a great deal of damage. When I emerged from my house to go to work the following morning, I observed various branches and detritus strewn around my yard, and I noticed that one particularly large branch had fallen right beside my car. If it had blown over just one or two centimeters further, it would have caused several hundred dollars worth of damage. As I stood beside my vehicle staring at the branch, it suddenly became clear to me why people are so eager to opt for supernatural explanations. At a quick glance, it seemed extraordinarily unreasonable that the branch would have come that close to hitting my car just by chance. It was an improbable event that my puny primate brain struggled to reconcile, and for the briefest millisecond it was tempting to think that some malevolent entity must have been watching out for me and my property. Being a rational person who understands the law of large numbers, however, I dismissed that explanation just as quickly as I generated it. What I realized was that my good fortune was nothing more than pure dumb luck [note: I am using “luck” synonymously with “chance” and am not implying that some force was acting in my favor].

When I considered all of the thousands of branches that had fallen during the previous night and all of the thousands of vehicles that had been parked near trees, it became obvious that we would expect a small subset of the branches to just barely miss hitting a vehicle. In other words, we would expect, just by chance, that lots of branches would fall away from vehicles, lots would fall on vehicles, and a few would fall right beside vehicles. There was nothing special about me or my car, there was no cosmic plan being orchestrated, I was just lucky. I just happened to be in the tail end of the probability distribution. Indeed, when I got on Facebook later that day, some of my friends were posting pictures of the damages that they had sustained, just as we would expect from a probability distribution. Conversely, other friends of mine had been lucky enough to avoid any repercussions of the storm, but, much to my dismay, they were quick to attribute their good fortunes to divine intervention, and give thanks to a supernatural entity who had protected them during the maelstrom. This is where I draw the line, this is what I have a problem with. It’s one thing to believe that God exists and to be thankful to him for life in a very general, ultimate sense. It is another thing entirely to make him into a cosmic puppeteer who is so concerned with the minutia of your life, and so directly involved in manipulating the physical world that he actually redirected branches to keep your precious property safe.

Why should we accept the scientific explanation?
Falling branches is admittedly a trivial example, but this pattern is widespread. I know many people who claim that everything from the precise genetic makeup of their children to the grade that they got on a test was a deliberate act of God. Perhaps the most common and disturbing form of this world-view appears at hospitals. People are extremely quick to distort medical marvels into divine miracles. On numerous occasions, I have seen someone recover from a cancer that has a high mortality rate, and instantly friends and family proclaim that it was a miracle! They claim that their prayers worked and God intervened and healed him. If we stop and think about it rationally, however, that explanation is hollow and lacking in logic.

Consider the following situation:

  1. Man X has cancer
  2. Man X takes a treatment that was designed specifically to fight cancer
  3. Man X recovers from his cancer
  4. Conclusion: It was clearly a divine miracle!

Hopefully the problem here is obvious. What justification could we possibly have for claiming that the recovery was miraculous when the person was taking scientifically tested medicine? Even in the rare case where someone recovers without seeking medical help, we know that the body has many astounding ways of healing itself, none of which require divine intervention.

The fundamental problems here is the burden of proof. By claiming that something was miracle, you have just placed the burden of proof on you to demonstrate that there was no possible scientific explanation. It’s not enough that an event was improbable, you must prove that it was physically impossible before you can claim that it was a miracle. It’s worth pointing out that to demonstrate that something was a miracle, you have to show that a scientific explanation cannot exist, rather than simply that one does not currently exist. History has clearly demonstrated that the lack of a current explanation does not mean that an explanation doesn’t exist. Indeed many physical phenomena, such as magnetism, were once attributed to the supernatural. So, you need to demonstrate that a scientific explanation absolutely cannot exist.

Let me give an example, suppose that on a clear, windless day, a regular person, wearing nothing but regular clothing jumped off of the Empire State building, flew over a mile (unaided), and landed safely on the ground. That would be a miracle because that would be an event that science simply could not explain. It would completely defy everything that we know to be true about physics. There wouldn’t be any conceivable future discovery that could explain that event, but here’s the important catch: no one has ever documented an event like that under properly controlled conditions and with reliable witnesses. It simply hasn’t happened. That doesn’t necessarily mean that miracles are impossible (that would be an argument form ignorance fallacy), but it does mean that we have never witnessed anything which we can safely call a miracle.

Another way to think about this is to consider Occam’s razor. This is the principle that, all else being equal, we should default to the explanation that makes the fewest assumptions, because that explanation is usually correct. Claiming that an event was miraculous requires numerous unfounded assumptions that cannot be proven. You have to assume that the supernatural exists, assume that this supernatural entity cares specifically about you, and assume that this entity actually acted on your behalf. None of these assumptions are necessary for the scientific explanation. In fact, no assumptions are necessary at all because we understand probabilities, causal relationships between medications and recoveries, etc. Therefore, the miraculous explanation is unparsimonious and should be rejected.

At this point, I generally find that people ignore everything that I’ve said and insist that the low probability of a given event somehow proves that it was miraculous. For example, I often have people proclaim that their recovery from cancer had to be a miracle because the doctors said they only had a 5% chance of survival. This is, however, no different from the branch example. Fine, you survived your cancer, but for every one survivor, there are 19 other people with that same cancer who didn’t survive. It only seems miraculous to you because you were lucky enough to be one of the outliers who made it. If you had been one of the 95% of people who didn’t make it, you wouldn’t be saying it was a miracle…because you’d be dead, and rather that talking about miracles, your family would be probably be spouting some nonsense about an incomprehensible divine plan to test their faith.

An easy way to think about this to think about winning the lottery. The odds that you will win are extraordinarily low, but if you win, you don’t get to claim that it was a miracle because so many people played that it was certain that someone would eventually win. Your victory was nothing more than the law of large numbers playing itself it out. Similarly, recovering from an aggressive cancer is not a miracle, it’s just probability theory running its course. So many people get cancer that, just by chance, a few of them will survive even the extremely aggressive ones.

Let me give another medical example to illustrate this. I often hear people describe rare births, such as quadruplets, as miracles because the odds of having them are extremely low, but when you consider all of the millions of people who give birth each year, we expect a few quadruplets to be mixed in there. So they only appear extraordinary and miraculous if you don’t consider all of the millions of perfectly normal births that occurred. Similarly, someone surviving an aggressive cancer only seems miraculous if you ignore all of the thousands of people who didn’t survive that type of cancer.

A final problem is the sheer hubris of a the claim that events in your life are miraculous. It elevates you to a place of extraordinary cosmic significance. Consider the branches example again. Could I really be arrogant enough to proclaim that God cares enough about me to shield my car from harm, but he couldn’t be troubled to do the same for the hundreds of people who awoke to find tree limbs jutting out of their windshields? Similarly, if you survived a cancer with a 95% mortality rate, what makes you so special that God elected to heal you, but didn’t bother with the 95% of patients who died from that cancer? Inevitably people will respond with something to the effect of, “God’s ways are not our ways,” but that’s ad hoc nonsense. There is no rational reason to conclude that these events are miracles.

Why does it matter?
Some people may be wondering why I went off on this tirade. After all, my blog is usually devoted to debunking anti-science arguments, not discussing philosophy. There are two key reasons that I think this topic is important. First, it has an extremely strong impact on how we view the natural world. It determines whether we are going to view the world as a logical, mathematical system or as a system in which probability is merely an illusion and everything is actually being carefully orchestrated by a divine puppet master. This is absolutely fundamental to whether or not we are going to accept science. If God is actually meddling with the world in the way that many people seem to think he is, then science is pointless. Suppose, for example, that we found a new cancer treatment that had a 30% success rate (as compared to the previous treatment’s 20% success rate for the type of cancer that it was designed for). If God was actually constantly performing miracles, that would mean that our “treatment” was actually worthless, because it was really all God. In other words, our treatment didn’t work, but it appeared that it worked because God was performing miracles more frequently than he was before, and in his divine wisdom he had decided to cure an additional 1 out of every 10 patients every time that we used this new treatment.

Many people will object to this and say that the science does work, but sometimes God steps in and helps out. This is, however, extremely inconsistent, and it deprives you of the ability to ever claim that anything is miraculous. If we follow this through logically, then if your recovery from a cancer with a 95% mortality rate was a miracle, but the science does actually work, that means that everyone else in the 5% recover group was cured by science. What justification could you possibly have for thinking that God intervened on your behalf, but not on the behalf of the rest of the 5%? In other words, why do you think that they were cured by science, but you were cured by a miracle? You can’t have it both ways. You can’t accept the miracles and accept the science. This is why I care about this topic: a belief in frequent miracles completely undermines science.

The second reason that I care about this is that it is a dangerous notion that leads to many anti-science views. For example, I frequently talk to parents who don’t vaccinate because they think that God will magically protect their children from illnesses. This goes beyond simple believing that a past event was miraculous, and it actually presumes that God will perform miracles for you in the future and will supernaturally destroy viruses and bacteria before they can harm your children. Religious global warming deniers often commit a similar blunder. I frequently hear them claim that God simply won’t allow us to destroy our planet, and the climate is somehow something which God will prevent us from modifying. As with the anti-vaccine argument, this view stems directly from the notion that God is constantly intervening in our lives. Similarly, we have all probably heard accounts of people who died from treatable illnesses because they decided to reject modern medicine and go to faith healers instead. This is the very real danger of accepting miraculous explanations instead of science. It completely distorts our view of reality to the point that science becomes trivial and meaningless, and that’s a frightening position for us to be in.

Conclusion
I want to reiterate that I am not attacking people of faith. I’m not saying that you can’t believe that the supernatural exists, but I am saying that you shouldn’t let that belief distort your view of the physical world. The universe operates according to logical, mathematical rules, and seemingly miraculous events are easily explainable using probability theory and science. That doesn’t necessarily mean that miracles don’t ever happen, but we have no evidence to show that they happen. Therefore, we cannot default to a supernatural explanation. A miracle is by definition something that science cannot explain, so anytime that a scientific explanation exists, we should accept that explanation rather than claiming that a miracle occurred.

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Reducing irreducible complexity

Posted on April 26, 2015 by Fallacy Man

Irreducible complexity is the cornerstone of the intelligent design movement, and it is a popular argument among young earth creationists as well. In simplest terms, this argument states that some systems are too complex to have evolved via natural selection because they have lots of parts and all of those parts need to be in place for the final product to function. Thus, no one part can be selected for until all of the other parts are already in place (it’s basically a chicken or the egg paradox). This is not a new argument. In fact, Darwin explained why this argument doesn’t work in Origin of the Species, and his rebuttal still works today. Nevertheless, despite the fact that this argument was defeated over 150 years ago, it is still a very popular argument today.

No one has done more to popularize this argument that Michael Behe. He championed this notion in his book, Darwin’s Black Box in which he shifted the target of this argument. You see, Darwin dealt with relatively large “irreducible” systems, such as eyes, whereas Behe focuses on tiny molecular machines such as the bacterial flagellum. Darwin’s explanation applies to these tiny machines just as well as it does to large systems, but given the immense popularity of this argument, I will explain the problems with Behe’s derivation of this argument (it irritates me to no end that I have to debunk an argument that was soundly defeated over 150 years ago).

The standard example of irreducible complexity is the mousetrap, so let’s start with that. A mousetrap is fairly simple and requires only a few pieces: a base, spring, arm, catch, and bait plate. According to Behe, this is an irreducibly complex system because all five pieces are necessary for it to function as a mousetrap. If even one piece was removed, it would not catch any mice. Therefore, according to Behe, a mousetrap could never have evolved via natural selection because natural selection is a gradual step-wise process, but no one step would be useful until all of the steps were in place.

If you have read my other posts on evolution, then the problem with this argument should be obvious: it ignores the fact that evolution is blind. I will fully admit that you need all five pieces for it to function as a mousetrap, but that is not the same thing as saying that you need all five pieces for it to function. This argument sets up a mousetrap as an ultimate endpoint that evolution is working towards, but that’s simply not how evolution works. It does not have any foresight or goal. So the parts don’t have to function as a mousetrap for nature to select them. Rather, they simply have to perform some useful function, and it is easy to think of uses for every single piece of a mousetrap. Springs are, for example, useful for many applications. Similarly, a block of wood has a nearly infinite number of uses. Thus, each piece of a mousetrap could be selected for a reason other than acting as a mousetrap. Then, random mutations could bring those pieces together, and as long as some useful function was performed, those combinations would be selected for. During a trial over teaching intelligent design, Kenneth Miller has famously illustrated this by wearing a partial mousetrap as a tie clip. It may not be the best fashion statement, but it makes an important point: you can have a useful function without having all five parts, and that’s all that natural selection needs.

Now, let’s apply this to a real world example. The poster child of irreducible complexity is the bacterial flagellum. This is an amazing structure that propels bacteria through their environment like a tiny motor. In most species, it requires 42 proteins to work, and if any one of them are missing, it will not function as a flagellum. Thus, according to Behe, the flagellum is irreducibly complex and could not have evolved because no one protein would be selected until all of the other proteins were already in place. The reality is that we know of useful functions that almost all of those proteins do elsewhere in the cell. Thus, each protein would have initially been selected in order to perform a function other than being part of a flagellum. Further, we know of multiple combinations of these proteins that are extremely important to cells. In fact, we have laid out an entire pathway that would result in the step-wise evolution of a flagellum, with each step requiring only one mutation and each step producing a useful product (you can see an animation of this pathway here). To put this another way, all 42 proteins are useful for other purposes, mutations can bring these proteins together to perform other functions, and further mutations can result in useful combinations of those clusters until we ultimately end up with a flagellum. In other words, the flagellum is not irreducibly complex.

We can clearly see from the bacterial example that the irreducible complexity argument is nonsense. It relies on a complete misunderstanding of evolution. Nevertheless, I have found that debating this topic with creationists is much like fighting a hydra. Every time that I explain how one supposedly irreducibly complex system could have evolved, they bring up some other system that they think is irreducibly complex. This brings up an important point. Namely, this argument is really just an argument from ignorance fallacy. It states the following, “I don’t understand how this evolved, therefore it didn’t evolve.” That’s not logically valid. Just because you don’t understand something doesn’t mean that it isn’t true.

At this point, I often get the response of, “fine, we have hypothetical mechanisms that would allow the immune system, flagella, the clotting cascade, etc. to evolve, but we have never proved that any of those pathways actually occurred.” This response totally misses the point, and it commits another argument from ignorance fallacy. Irreducible complexity states that these systems cannot evolve. This is a universal claim, and all that it takes to defeat a universal claim is a single example to the contrary. So, for example, I do not have to prove that the evolution of the flagellum followed the exact pathway outlined in the video, because the simple fact that a possible pathway exists demonstrates that the flagellum could have evolved. We don’t have to prove how it evolved, we just have to show that it could have evolved. Irreducible complexity is an all-or-nothing argument. Either these systems can evolve or they can’t, so by providing even one example of how they could have evolved, we have completely defeated the argument.

Further, even though we do have hypothetical pathways for essentially all of the supposedly irreducibly systems, having pathways for every single one is totally unnecessary because the argument itself is so fundamentally flawed. It relies entirely on the concept that evolution has a goal that it is working towards, and we know that evolution doesn’t operate that way. As long as a given mutation is in some way useful, it will be selected for.

In conclusion, irreducible complexity is based on a fundamental misunderstanding of one of the most basic and important concepts of evolution: mutations do not need to be useful for some ultimate endpoint in order to be selected, they just have to be useful. Further, we have hypothetical pathways for the evolution of systems that are supposedly irreducibly complex, and any one of these pathways is sufficient to complete debunk this argument. To demonstrate that a system is truly irreducibly complex, you would have to prove that its parts are only useful for the system in question, and no one has ever been able to do that. Until someone can do that, until someone finds a system in which it is clear and unambiguous that the parts involved are only useful for that system, this argument simply doesn’t work, so please stop using it.

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