Metaphysics and the Human Body

From a lecture series presented by The Great Courses

Before the Enlightenment, the metaphysical view of the human body was that of a machine, and all problems with the machine could only be caused by parts of the machine malfunctioning. Removing or fixing those parts was the job of surgeons, and the idea that tiny animals inside us could make us sick—that seemed silly. But a new scientific paradigm born of the Enlightenment changed humanity’s view of the body.

Digital x-ray human body scan interface on blue background 3D rendering

The metaphysics of the human body has an interesting history. The Dutch scientist Antonie van Leeuwenhoek had discovered the existence of what would come to be called bacteria with his microscope in the 1670s, about 200 years earlier, but they were just a curiosity. Scientists at the time thought there is no way that things so small could affect the functioning of human bodies, machines so much bigger and stronger. But that is exactly what was happening, and the emerging scientific paradigm would soon alter our understanding of the human body.

The Germ Theory of Illness

After Frenchman Louis Pasteur’s work soon after, the germ theory of illness became accepted and we had to change our picture of reality. Suddenly, we were not ghosts in a machine, but something completely different. We were now castles, surrounded by hostile forces. Danger surrounds us in the form of inferior one-celled barbarians at the gates of our bodily temples. Blood was no longer thought of as oil or hydraulic fluid flowing through the tubes of our veins, but when examined closely, the white blood cells were now thought of as our sentries and armed guards doing battle with the invaders whenever they broke through the walls into our corporeal citadel.

Male body,man surrounded by microbiome spherical cloud of bacteria, viruses, microbes. 3d rendering.
Danger surrounds us in the form of inferior one-celled barbarians at the gates of our bodily temples.

This thinking was a new and completely different foundation from which to understand human physiology and health. In the century that followed Ignaz Philipp Semmelweis, a 19th-century physician who was an early pioneer of antiseptic procedures, this standpoint led to vaccines that eradicated diseases from small pox to polio. It led to a new way of life—now cleanliness was not just next to godliness; it was the source of continued life itself. The dangers of nature were not lions, and tigers, and bears, oh my; they were streptococcus, staphylococcus, and E. coli, oy vey.

The word sterile did not mean devoid of life anymore, but rather it now meant safe for life. We had to hide from nature in order to be helpful.

Learn more about germ theory

Think of Fantastic Voyage, the Isaac Asimov book and the film from the mid-1960s. The film, with Stephen Boyd and Raquel Welch, focuses on a scientist who has perfected a miniaturization process while under the control of the Soviets. The Americans smuggle him out, but an assassination attempt has left him on the verge of death. A team of Americans is temporarily shrunk along with a vehicle to travel through his bloodstream and destroy the life-threatening blood clot with their lasers.

The battles raging inside the body are shown to be as dangerous as the Cold War outside. The team is threatened by aspects of the machine—the violent beating of the heart could crush them—but also by the normal state of war inside the body. They see bacteria and antibodies locked in a deadly struggle and if the team finds itself in the middle, they could wind up as collateral damage from either one of them. Not only the bacterial invaders, but the body’s own defenses could be turned against them.

Science and Science Fiction

The image of the human body itself became an appropriate setting for an adventure story. At the same time as Pasteur was showing us that the world is full of bacteria doing various things to us, we find the writings of Jules Verne and H. G. Wells, the original science fiction writers, who were positing new worlds at the bottom of the ocean, on the Moon, and back in time. It was a period of great discoveries, and the uncertainty associated with seeing the world contains things we had never seen before—that uncertainty is jarring. Fantastic Voyage is clearly designed to be a 1960s version of Jules Verne, whose collected stories are titled Voyages Extraordinaires. The entire genre of science fiction comes out of—and is informed by—the need to redefine reality with our scientific advances. Scientific writers envision a future with new scientific and technological advancements, and then challenge us to figure which of our contemporary concepts, ideas, and foundational beliefs still remain, and which will require either tweaking or complete replacement.

This is a transcript from the video series Redefining Reality: The Intellectual Implications of Modern Science. Watch it now, on The Great Courses Plus.

Thomas Kuhn thought very carefully about this process of redefining reality as a process of scientific change. Kuhn was an American physicist, trained at Harvard in the 1940s, and he thought it strange that when he had to teach the introductory physics class that all physics professors have to teach, what students are made to learn is Newtonian mechanics, the physics of the 17th century. This is the science that had been overthrown. Albert Einstein’s theory of relativity and the subsequent development of quantum mechanics led to a revolution in physics—and he took this notion of revolution quite seriously. As in a political revolution, the old concepts and the reality they defined had been completely replaced with a new structure.

A portrait of Tomas Kuhn
American historian, physicist, and philosopher Thomas Kuhn

Yet, we were teaching our science students as if the old ideas were still defining our view of reality. We don’t teach them what scientists are doing now and we don’t teach our students why the scientists back then believed the things they did. We just teach them how to use Newton’s toolbox to solve types of problems. We give them tests on which they are challenged to solve problems, but what we’re really assessing is their ability to properly use the tools we have given them. But we never tell students where those tools came from, or what tools were used by earlier scientists, or why those earlier tools fell out of favor. We don’t tell them until much later on that we have replaced those tools with even newer ones that scientists currently use.

Learn more about competing visions of the scientific method

Kuhn thought about what that meant and why that was done. The result was his groundbreaking work The Structure of Scientific Revolutions, published in 1962. The book shook the basis of what we thought science was, and how it affected the way we see the world. Kuhn’s book argues that when we think of the archetype of the scientist, what comes to mind are big names like Newton, Darwin, and Einstein. But this is a false picture of real science. Science as it is done day in and day out by working scientists is not at all like what these towering figures were doing. These are revolutionary scientists whose work is different in kind from that of what Kuhn calls “normal” scientists. Normal scientists do normal science and normal science is not revolutionary—quite the opposite.

Working inside Philosophy’s Paradigm

Normal scientists work within what Kuhn called a paradigm. Paradigms are powerful—they give us the definitions of our scientific terms; that is, they tell us what we need to believe are the basic elements of reality. The paradigm tells us what counts as a legitimate question, what tools we can use to answer those questions, and what counts as a legitimate answer.

Normal science occurs when someone takes a question deemed meaningful by the paradigm, uses the tools prescribed by the paradigm to find an acceptable answer within the paradigm. This solution is then published in a journal whose editors and referees are senior members of the community dependent upon the paradigm, indeed whose most powerful members are the senior people who helped establish the paradigm. That publication can help get one recognized in the community, it can help you get tenure at your institution and keep your job. If you want to feed your children, you need to play according to the rules dictated by the paradigm and enforced by the community.

Scientists do not question the paradigm. They teach their students how to act according to it, but to challenge the paradigm is to challenge rationality itself. Rationality, Kuhn argues, only exists within the paradigm. Since the paradigm tells us what’s real and how it works, to question the paradigm is to question the structure of the world itself, and that leads to nonsense according to those within the paradigm. To think about the paradigm instead of through the paradigm is to engage not in science, but in philosophy. To a scientist, this is a complete waste of time. There are real problems to be solved inside the paradigm; questioning the foundation accomplishes nothing.

What about the Anomalies?

Occasionally, there will be questions that the paradigm accepts as legitimate, but when the proper tools are applied, the answer fails to be one the paradigm recognizes. The first reaction is to blame the normal scientist. “You made a mistake. Check your calculations. Check your equipment. Recalibrate your meters. You did something wrong.” Sometimes it was a problem with the meter, or someone forgot to carry the one, or something that’s easily explained; the paradigm is preserved, and everyone breathes a little easier.

But sometimes the problem is not so simple. These anomalies are set aside for particularly clever people to come along and figure out. A rising star may come up with a nifty twist or a new tool that could sort it all out. And sometimes they do.

Learn more about how we think and how to think better

But sometimes nobody solves the anomaly. What happens then? According to Kuhn, the unanswered anomalies are swept under the rug, ignored as long as possible, until there are enough of them or anomalies so significant that they cannot be hidden from view. At this point, the community is thrust into what Kuhn calls crisis. A scientific community in crisis is forced to do something they despise—philosophy. They have to consider the paradigm. If the crisis is severe enough, some will start thinking the unthinkable; maybe we need to utilize a different paradigm, a new set of basic concepts, a new structure to reality itself.

These people are seen as nonscientific by those in the community because scientific thought is defined by the paradigm. But if the normal science within the new paradigm starts to look good, some will jump ship, leaving the old for new ways of seeing things. According to Kuhn, there is never a good reason to move from one paradigm to another—indeed, there could never be because the very concept of good reason requires rationality which only exists within the paradigm. There may be pragmatic reasons or personal reasons, but the move is equivalent, Kuhn contends, to a religious conversion in that it trades living in one sort of reality for another. Paradigms, he says, are not to be treated lightly.

If a critical mass of scientists adopts the new paradigm, so it becomes the more widely accepted approach, then we have a scientific revolution. In the same way that a political revolution completely changes the system of government—that is, the legislative reality on the ground is replaced with another—so too, with a scientific revolution do we replace one reality with another. Scientific revolutions, according to Kuhn, force us to redefine reality.

From the lecture series Redefining Reality: The Intellectual Implications of Modern Science, taught by Professor Steven Gimbel

Images courtesy of:
Davi.trip [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)] via Wikimedia Commons