Paradigm Shift Explained
You hear the phrase “paradigm shift” all the time, and not just in philosophy. People talk about paradigm shifts in all sorts of areas: medicine, politics, psychology, sports. But what, exactly, is a paradigm shift?
What is a paradigm theory?
A paradigm theory is a general theory that helps to provide scientists working in a particular field with their broad theoretical framework–what Kuhn calls their “conceptual scheme.” It provides them with their basic assumptions, their key concepts, and their methodology. It gives their research its general direction and goals. It represents an exemplary model of good science within a particular discipline.
'Paradigm shift' in philosophy?
This refers to any revolutionary change in the fundamental intellectual framework that has traditionally been adopted by practitioners of a subject. The idea was proposed by American philosopher Thomas Kuhn in The Structure of Scientific Revolutions. Kuhn believed that the central ideas of a discipline generally do not change within a short span of time or because the current practitioners readily change their minds when they are introduced to new and better ideas. Instead, he argued, paradigm shifts happen when people of the older generation die and are replaced by younger people who are more receptive to newer ideas.
A paradigm shift occurs when one paradigm theory is replaced by another. Here are some examples:
- Ptolemy’s astronomy giving way to Copernican astronomy
- Aristotle’s physics (which held that material objects had essential natures that determined their behavior) giving way to the physics of Galileo and Newton (which viewed the behavior of material objects as being governed by laws of nature).
- Newtonian physics (which held time and space to be the same everywhere, for all observers) giving way to Einsteinian physics (which holds time and space to be relative to the observer’s frame of reference).
What causes a paradigm shift?
Science can’t really get going until most of those working within a field agree upon a paradigm. Before this happens, everyone is doing their own thing in their own way, and you can’t have the sort of collaboration and teamwork that is characteristic of professional science today.
Once a paradigm theory is established, then those working within it can start doing what Kuhn calls “normal science.” This covers most scientific activity. Normal science is the business of solving specific puzzles, collecting data, making calculations, and so on. E.g. Normal science includes:
- working out how far each planet in the solar system is from the sun
- completing the map of the human genome
- establishing the evolutionary descent of a particular species
But every so often in the history of science, normal science throws up anomalies–results that can’t easily be explained within the dominant paradigm. A few puzzling findings by themselves wouldn’t justify ditching a paradigm theory that has been successful. But sometimes the inexplicable results start piling up, and this eventually leads to what Kuhn describes as a “crisis.”
Examples of crises leading to paradigm shifts:
- At the end of the 19th century, the inability to detect the ether–an invisible medium posited to explain how light traveled and how gravity operated– eventually led to the theory of relativity.
- In the 18th century, the fact that some metals gained mass when burned was at odds with phlogiston theory. This theory held that combustible materials contained phlogiston, a substance that was released through burning. Eventually, the theory was replaced by Lavoisier’s theory that combustion requires oxygen.
What changes during a paradigm shift?
The obvious answer to this question is that what changes is simply the theoretical opinions of scientists working in the field. But Kuhn’s view is more radical and more controversial than that. He argues that the world, or reality, cannot be described independently of the conceptual schemes through which we observe it. Paradigm theories are part of our conceptual schemes. So when a paradigm shift occurs, in some sense the world changes. Or to put it another way, scientists working under different paradigms are studying different worlds.
For example, if Aristotle watched a stone swinging like a pendulum on the end of a rope, he would see the stone trying to reach its natural state–at rest, on the ground. But Newton wouldn’t see this; he’d see a stone obeying the laws of gravity and energy transference. Or to take another example: before Darwin, anyone comparing a human face and a monkey’s face would be struck by the differences; after Darwin, they would be struck by the similarities.
How science progresses through paradigm shifts
Kuhn’s claim that in a paradigm shift the reality that is being studied changes is highly controversial. His critics argue that this “non-realist” point of view leads to a sort of relativism, and hence to the conclusion that scientific progress has nothing to do with getting closer to the truth. Kuhn seems to accept this. But he says he still believes in scientific progress since he believes that later theories are usually better than earlier theories in that they are more precise, deliver more powerful predictions, offer fruitful research programs, and are more elegant.
Another consequence of Kuhn’s theory of paradigm shifts is that science does not progress in an even way, gradually accumulating knowledge and deepening its explanations. Rather, disciplines alternate between periods of normal science conducted within a dominant paradigm, and periods of revolutionary science when an emerging crisis requires a new paradigm.
So that is what "paradigm shift" originally meant, and what it still means in the philosophy of science. When used outside philosophy, though, it often just means a significant change in theory or practice. So events like the introduction of high definition TVs, or the acceptance of gay marriage, might be described as involving a paradigm shift.