The ancient Greeks proposed a geocentric model of the universe.¹ That geocentric model claimed that the earth was stationary and that the planets, sun, and stars revolved around it. Looking back at the Greek’s view of the universe with the knowledge we have now, it is clear that they were wrong in their way of thinking. However, imagine that we were those same ancient Greeks. From the perspective of the Greeks, it would seem that everything does, in fact, revolve around the earth. We have a moon, we see planets moving towards us and every day we see the sun rise in the east and set in the west. Clearly, we have to be the center of our universe! Geocentricism became a theory that answered a series of questions about the nature of the observed cosmos. It answered a lot of questions; but it did not answer them all. Greek, and later Roman, astronomers just could not figure out why the planets seemed to deviate from expectations of the theory, namely that they should be moving around the earth in perfect circular motions. Instead, they seemed at times to stop and move backwards, something they called retrograde motion. Geocentrism, while it answered many questions about the universe, found this observed phenomenon to be an anomaly. Ancient astronomers focused on this anomaly, and one of them, the Roman astronomer Ptolemy, offered a solution. He proposed that when the planets moved in retrograde motion, they were moving in a motion known as epicycles. Planets still followed their circular paths around the earth, which the theory of geocentrism expected. But they also makes loops along that path (imagine a stretched out slinky in the shape of a circle). The explanation of epicycles explained the anomaly of retrograde motion within the theoretical framework of the geocentric theory. Ptolemy’s work remained the textbook explanation for planetary motion for the next fifteen hundred years. It wasn’t until Nicolaus Copernicus’s work in the sixteenth century that an alternative theory, heliocentrism, emerged to compete with geocentrism.² Shock waves were sent through the early modern scientific community as this revolutionary new perspective on our universe still answered all of the old questions, but better accounted for their anomalies than did the older, respected, and cherished perspective. Now scientists had to make a choice. Do they stay with the old “theory” and continue to conduct research using that model? Or do they follow Copernicus’s new model and do research using that model? Ultimately, it was up to each scientist to make the decision. While it did take a while to gain traction, the heliocentric model won the converts over. It was under the assumption of this model that Johannes Kepler accurately described the elliptical motion of Mars, which would have been impossible within the geocentric model.³

How did science developed during these centuries? The typical or traditional view of science is that science is a linear accumulation of knowledge, piece by piece of observed data being handed on to each succeeding generation of scientists. But when we look at the emergence of the heliocentric model, this linear accumulation theory of science may not hold up. For many centuries science was, in fact, cumulative. But the shift in Copernicus’s thinking was not simply the addition of more or new knowledge into the web of already existing data. Geocentric thinking was essentially a box containing all of the possible ways a scientist could conceive of the universe within the assumptions of geocentricism. This scientific world-view explained what it needed to explain adequately enough to not be challenged for fifteen hundred years. Copernicus was the first to think outside of the geocentric box to propose a new box with new assumptions that would address old problems, but also address new ones unthinkable within the old box.⁴ Seemingly out of nowhere, this new theory caught the attention of many scientists, and science now had two sciences! Science, which had been seen as a linear accumulation of knowledge, could no longer be viewed that simply. What we had here was a revolution!

American physicist and philosopher of science Thomas Kuhn recognized this non-linear development of science and dub such eruptions as paradigm shifts. Kuhn would have his breakthrough insight as a Ph.D. student at Harvard in 1946. During this time he was helping James Conant, the president of Harvard, develop a general science course for undergraduate students. While helping Conant, he encountered various writings that had been crucial to the development of science, including Aristotle’s Physics.⁵ After coming across them, he realized it was wrong to judge past scientific understandings of things by our own standards of understanding things. If we really want to understand the past, we have to step into their shoes and see what conceptual framework they were working with when they described their phenomena.

In order to discuss paradigms, it important to establish what a paradigm is, what its key features are, and how to determine when a paradigm shift has occurred. According the Kuhn, a paradigm is an achievement that is “sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity. Simultaneously, it was sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners to resolve.”⁶ So, a paradigm has to be new enough for a scientist to consider leaving his or her current scientific framework (or paradigm), while at the same time establish a new framework to work in. From then on, a paradigm is in one of two states: normal science or crisis. Normal science is “research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice.”⁷ During normal science, the scientific community works on the assumptions that this framework is the correct one, and it begins to work on solving problems within that framework and under its assumptions. Rather than call the issues within science problems, Kuhn referred to them as puzzles, as a “project whose outcome does not fall in that narrower range is usually just a research failure, one which reflects not on nature but on the scientist.”⁸ Scientists go into research knowing what they are looking for, just how one does a puzzle, knowing the solution. If they cannot seem to find the solution to the puzzle and make everything fit, scientists will tunnel vision on making the pieces fit.

Whenever scientists cannot seem to make something fit into the expected, that something becomes an anomaly or “violations of expectation.”⁹ For the most part, scientists largely ignore such anomalies and assume that they can and will eventually be solved with a different technique or technology. Eventually, an anomaly will occur where no matter what scientists do, they simply cannot find a solution to it: “the anomaly had lasted so long and penetrated so deep that one can appropriately describe the fields affected by it as in a state of growing crisis.”¹⁰ During this crisis, “the rules of normal science become increasingly blurred. Though there still is a paradigm, few practitioners prove to be entirely agreed about what it is.” People begin to question the paradigm that is currently in place when it cannot find suitable solutions, and they begin looking outside the paradigm for answers. During this time period, various equally valid paradigms are proposed and battle for acceptance.¹¹ A paradigm does not need to have all the answers from the start. Whichever one can provide the better framework for research will usually emerge victoriously.¹² After a new paradigm is chosen, science resumes back to normal science, and eventually the cycle will repeat itself. The entire process is called a scientific revolution, which is a “noncumulative developmental episode in which an older paradigm is replaced in whole or in part by an incompatible new one.”¹³

One of the most controversial parts of Kuhn’s suggested paradigm shift is his suggestion that science is not linear. Prior to Kuhn, science was thought to be a linear accumulation of knowledge, where more and more is known over time.¹⁴ Kuhn threw this notion away and suggested that only normal science is cumulative: “Transition from a paradigm in crisis to a new one from which a new tradition of normal science can emerge is far from a cumulative process.”¹¹ Even more controversial was the suggestion he makes at the end of The Structure of Scientific Revolution: “We may, to be more precise, have to relinquish the notion, explicit or implicit, that changes of paradigm carry scientists and those who learn from them closer and closer to the truth.” In Kuhn’s usage, truth is in reference to science arriving at total knowledge. With paradigms in place, science will never be able to find some “final truth theory” since some knowledge will lay outside of the established paradigm.

This final statement made some members of the scientific and philosophical communities uncomfortable as some believed that science without a goal cannot exist.¹⁶ An enormous criticism of Kuhn was the lack of clarity he gave to the word paradigm. Within The Structure of Scientific Revolution, he was found to have used the word paradigm a total of twenty-one different ways.¹⁷ Secondly, scholars were able to find counterexamples to Kuhn’s scientific revolutions, such as the shift from Mendelian genetics to modern molecular genetics, directly challenging the most important criteria of paradigms being incompatible and non-cumulative.¹⁸

Despite these “shortcomings,” Kuhn was ultimately correct in asserting that science has no end goal, but can and will continue to develop through paradigms and scientific revolutions. He would keep track of his critics and publish a series of essays during the 1970’s where he would clear up ambiguities in the concept of paradigm. His response would also in turn address the seeming cumulative nature of paradigms and clear up how scholars are mistaken for seeing this paradigm shift as cumulative. With a clearer definition of a paradigm, the compatibility issue was also addressed. As for those who would like to argue that scientists need a goal to pursue, Kuhn directly addressed this in the original publication of The Structure of Scientific Revolutions, that science does not need a goal to progress. For this, he used Charles Darwin’s On The Origin of Species to illustrate the comparison of the end goal of science to that of an autonomous evolutionary process that has no goal.

Kuhn noted one of his critics, Margaret Masterman, as crucial for his developing a clearer definition of what a paradigm is, as she mentioned how paradigms set the framework for science when there are no theories in place.¹⁹ Throughout the 1970’s, Kuhn would publish a series of essays and revise The Strucutre of Scientific Revolutions to give paradigms a clear definition and distinguish them from theories. Theories are how we define the phenomena using words, and exemplars are the ways that we learn theories; and change in exemplars are the paradigm shifts themselves. Theories are inflexible in that they cannot be changed or modified without completely changing the theory, while exemplars are flexible since they must be able to be modified to solve similar problems.²⁰

In order to be considered a new paradigm, it must be a noncumulative process and must be incompatible with the prior paradigm. A favorite counterexample to this among scholars lies in genetics, as they see the shift from Mendelian genetics to modern genetics as a cumulative process and compatible with one another.¹⁸ Gregor Mendel is known for his famous experiments with the breeding of pea plants. Through careful experiments, he was able to make observations of the plant breeding and determined that every parent has alleles (traits) that are passed on to their children. Within the handed down traits lies dominant and recessive traits, which determine what trait an organism will display. Ultimately, Mendel wanted to understand how inheritance works. As the field continued to develop, scientists were momentarily side-tracked when DNA entered the picture. To continue working on the first goal, scientists needed to understand how DNA was structured. In 1953, James D Watson and Francis Crick described the structure of DNA. With the structure of DNA now known, modern genetics could proceed. Genetics could now “shift” from trying to understand what DNA is to trying to understand how genes (a segment of DNA) function in the hereditary process. As groundbreaking as this was, it had happened by accumulation. Maurice Wilkins and Rosalind Franklin were responsible for finding a repeating structure of molecules in DNA in 1951. Preceding Watson and Crick was Edwin Chargaff who discovered DNA had to have matching base pairs in the 1940’s.

Simply put, scholars who refer to any major changes within a field as paradigm shifts misunderstand what a paradigm is. “A revolution produced within one of these traditions will not necessarily extend to the others as well.”²² Quantum mechanics, was revolutionary to only those who were working on microscopic particles. Scientists who deal with galactic objects like stars and planets, may take note of such a finding in quantum mechanics, but largely do not care since it does not directly affected their work or the assumptions of their work’s conceptual framework. This is like thinking about lawyers who have different specialties. One lawyer might deal with immigration laws and another with injury cases. A change in immigration law will overall effect everyone within society, but it would be revolutionary to the immigration lawyer since it directly deals with his specialization. The injury lawyer may slightly care since it involves law, but overall, it will not have too much of an impact on him. This effect is natural as scientists get more and more specialized within their careers. Genetics is a very specific subsection of biology and this change only affects those who specialize in genetics. More so, scientists can choose to get further specified and continue working on refining the structure of DNA or the effect of how genes work. The introduction of DNA does not change the fact that Mendelian and Modern genetics have the same end goal. Both aim to understand how traits (via alleles or genes within DNA) are passed down to an offspring. Introducing DNA, and momentarily shifting the focus of scientists, is not enough to constitute any kind of major change, much less a paradigm shift. If they do not meet the clearly established definition of a paradigm, then no paradigm shift took place. All that happened, was Kuhn’s normal science was working in order to solve the hereditary puzzle.

With the definition of paradigms and counterexamples addressed, it finally appears that Kuhn’s paradigms were now a suitable framework to describe the progress of science. Yet, scientists and philosophers would pick at the fact he would assert that science has no end goal. Initially, Kuhn’s making this assertion makes no sense, as he asserts that in order to be a scientist, one must have the goal to find some kind of “truth,” and without that belief, “no man is a scientist.”²³ This lines up with the popular notion that science needs an end goal to operate. However, Kuhn stated that the exact opposite happens. Science progresses (due to changes in paradigms) but does not progress towards anything. Conceptually this is seemingly hard to grasp since we evaluate progress relative to a set goal. In order to get his point across, Kuhn made an excellent comparison to the equally controversial On The Origin of Species by Charles Darwin. Evolution, according to Darwin, is the gradual development of species via natural selection. Species have a diverse set of characteristics but only those who possess a characteristic that gives them an advantage will survive and pass on those traits. Evolution also has no end goal; it is simply the mechanism by which life develops.²⁴ Kuhn drew the parallel between the evolutionary process to paradigms. Evolution was one of the biggest scientific discoveries, and has forced us to reconsider how life evolved on earth. Despite there not being a goal, an autonomous process unfolds. That does not mean that it does not continue to develop. Scientific paradigms function in the exact same way in that they develop and evolve, but they have no goal or end or telos.²⁵

Many scholars continue to disagree with the theory of paradigm and paradigm shift, as it is a deeply philosophical question about the nature of science and scientific inquiry. But generally, if evolution came to be accepted, there is no reason that paradigms could not as well, especially with a precise definition. Ultimately, Kuhn’s viewpoint on scientific development has ended up being accepted not only by scientists but by those in other academic fields and disciplines as well. It is a great theoretical framework for describing how an entirely new world and field can open up, simply by changing one’s perspective. Science is beautiful in that it can develop, without needing an end goal other than the simple quest to know. Some new discovery may be out there waiting for us to shift our perspective and find a completely new way to understand our world and ourselves within it. By definition, no theory is ever final, no matter how many times we may prove it to be right.²⁶ All it takes is simply one time for it to be wrong for a theory to be disproved. In the year 1900, Thomas Kelvin famously states: “There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.” Yet, in the last one hundred years, physics has made phenomenal strides due to the emergence of quantum mechanics, relativity, and various other paradigms. These landmark discoveries solely took place due to thinking outside of the paradigm or outside of our conceptual box. Accumulation only got us so far, as seen by Thomas Kelvin’s remark. It was the radical changes, the shifting of paradigms that enabled science to advance when it faced a round of anomalies within its conceptual framework of normal science.