Cause and Effect: The Last Refuge of Denialists, Part One

 

In my book Scientifically Thinking (Chapter 9), I explain the different kinds of cause and effect. Almost everything that happens has more than one cause.

Consider the example of hierarchical causation. An example of this is AIDS. If an AIDS victim dies of pneumocystis pneumonia, then you could say he was killed by the Pneumocystis carinii germ. But the reason the germ got a chance to spread was the depletion of the immune system, caused by HIV. The hierarchy of causation is, therefore, HIV—immune depletion—Pneumocystis. You cannot say “HIV does not cause pneumocystis pneumonia; Pneumocystis does.” The simple fact is that they both do, in a hierarchical fashion.

A very real example of people using hierarchical causation to mislead public opinion regards gun laws. I have heard “gun rights” people say that “Guns don’t kill people; people kill people.” The simple fact is that people use guns to kill people. It is hierarchical causation. Nobody believes that guns jump up and start shooting all by themselves. It is just a deliberate argument by the gun lobby to heap ridicule upon even mild versions of gun control.

Washington Post photo

This can lead to a dangerous situation. Many people have lots of guns and are ready to use them at the slightest provocation. And the social pressures against them are dwindling. Some white separatist groups openly display their weapons, clearly wanting us to know that they are ready to use them if something happens that they do not like. During the September 29 presidential debate, Donald Trump said that white supremacist groups should “stand by.” He clearly wants them to be ready to use their guns at some unspecified time in the future.

Another kind of causation that is misused by conservative denialists is multiple causation. This is one that has been deliberately propagated by Donald Trump. Covid-19 is caused by the coronavirus. The United States has now had more than 200,000 coronavirus deaths. But Donald Trump did not believe this. He believed that anyone who died of coronavirus but had previous underlying conditions should not be counted as coronavirus deaths. If you die of coronavirus, but you are old, then you died of being old, not from the coronavirus. Or if you have diabetes, and die of coronavirus, then you died of diabetes, not of coronavirus. Read about it here [https://www.cbsnews.com/news/covid-it-affects-virutally-nobody-trump-coronavirus-rally/]. I have not heard whether, since his diagnosis and return from the hospital, he has changed his mind about this.

The simple fact is that coronavirus deaths, in fact all deaths, have multiple causation. If a diabetic dies of coronavirus, the diabetes had weakened his or her health, and the coronavirus finished him or her off. Both the virus and the diabetes caused it. By Trump’s line of reasoning, if I (a pre-diabetic over 60 years old) die of coronavirus, it is not a coronavirus death. The simple fact is that I am getting along fine right now and am not on the brink of death; if I become ill with coronavirus, this is the spark that starts the fire. It would still be a coronavirus death.

Science denialists like to claim that, in cases of multiple causation, they can choose one of the causes and ridicule the others. This is especially true of global warming denialism, the subject of the next essay.

How Biology Is, Or Is Not, Different: Thoughts from Ernst Mayr

Ernst Mayr was one of the leading figures in modern biology. He was the last surviving architect of The New Synthesis of evolution. And he kept writing books until he died at age 100 in 2005. Because of his age, his writing is fairly clear: he knew he did not have time to go off onto tangents. He had to get to the point, since he knew any sentence might be his last.

One of his main points (expressed in two books, This is Biology and What Makes Biology Unique?, which are very similar but not quite the same) is that biology cannot be judged by the same standards of scientific rigor as the physical sciences. Yes, we all know that biological systems (such as organisms) follow natural laws. But each biological phenomenon is the result of such a prodigious number of interacting natural laws that you can never exactly predict what is going to happen. The best example is evolution. Immanuel Kant said that there would never be a Newton for a blade of grass. Several writers have noted that Darwin became that very person.

But Darwin was a “Newton for a blade of grass” because he changed our view of biology the way Newton changed the view of physics. What Darwin did not do was to establish a system by which the exact course of evolution could be predicted. One reason for this is that each organism is unique, while each electron is the same as every other electron. It is true that the molecules in a glass of water are different from one another; each has its own kinetic energy, and some of them have hydrogen and/or oxygen atoms with extra neutrons. Although one could say that a glass of water has a “population” of molecules, they do not differ from one another in the extreme way that organisms in a population do.

I will let you read Mayr’s books, if you wish. But I want to remind all of us that there are some laws of nature that biological systems always follow. They include:

• The rate of diffusion (of molecules, heat, electrons, etc.) is proportional to the concentration or energy status divided by the resistance. One of the components of resistance is distance; it takes a molecule four times as long to diffuse twice as far. This is why diffusion is rapid over short distances, such as a synapse, and slow over long distances, such as a room. This is true everywhere in biology. This is why leaves and animal tissues both have numerous, tiny vessels. I am aware of no exceptions.
• A related concept is that an increased surface-to-volume ratio increases chemical activity. This is why kindling burns faster than a log, and why bacteria can metabolize so quickly. Any exceptions?
• A third example is from fluid dynamics. The rate of fluid flow is proportional to the fourth power of the diameter of the vessel. This law is always true for laminar flow, such as in blood vessels and xylem. Any exceptions? For larger things, such as water pipes, gas pipes, and rivers, it is almost true, but turbulent flow (when the fluid starts roiling around) slows the fluid down.

Most scientists agree with Mayr. This is the main reason that I am seldom interested in mathematical models of biological phenomena. A few decades ago, various botanists figured out equations for how much transpiration was needed to cool a leaf off, and how big or small a leaf should be to keep from overheating, and other such things. The equations gave a verisimilitude of precision. Actual leaves may or may not follow these equations precisely. They are good generalizations, but no more than that.

I recommend the writings of Ernst Mayr, even if you are not a professional scientist. Even at age 100 he had an all-encompassing mind.