Homeopathy vs. modern medicine. Astrology vs. Astronomy. Intelligent design vs. evolutionary biology.
Debates between scientists and pseudoscience supporters have increasingly infiltrated the public domain. Intelligent design proponents want the theory to be taught as a science; homeopathy practitioners claim to cure illness with highly diluted ingredients despite contrary scientific findings; and astrologers make constellation-based predictions found in the back page of newspapers worldwide.
Most experts tend to agree on what areas constitute pseudoscience, such as the three listed above. But what criteria should we use to differentiate between science and pseudoscience or the broader category of non-science?
Called the demarcation problem, this question has kept philosophers and scientists busy for over a century. So what is science? What test can we apply to a theory to see if it's scientific? No one has unambiguously answered these questions, but philosophers of science have made some headway in the debate over the last 50 years.
One of the most influential thinkers on this topic was the 20th century philosopher Karl Popper. He thought that the defining characteristic of science was falsifiability -- the ability to generate hypotheses that could be proven false by observations or experiments. So why did Popper chose falsifiability as the distinguishing factor between science and non-science? That answer lies in his thoughts on the theories of two famous 20th century thinkers: Albert Einstein and Sigmund Freud.
Psychoanalysis vs. General Relativity
In Popper's mind, Freudian psychoanalysis was certainly not scientific. Because psychoanalysis tried to explain all of human behavior, Freud's theory never presented claims that could be proven wrong. The primary goal and supposed strength of Freud's enterprise made it unscientific, according to Popper.
Popper certainly didn't think that tests like these proved the truth of a theory, however. Instead, he thought that risky predictions that passed a test, such as Einstein's light bending hypothesis, only corroborated scientific theories. He thought that we could never truly verify a scientific theory, so the aim of science is to constantly try to refute theories with risky tests.
But Popper's thoughts on the topic didn't settle the demarcation problem. For instance, some have argued that astrology can make some falsifiable claims (that turned out to be false), and Popper would have to classify it as a scientific theory, albeit false one.
In fact, his work influenced a great deal of philosophers who later disagreed with him. Perhaps the most famous contributor after Popper was Thomas Kuhn, a philosopher who coined the modern day usage of the word paradigm.
Paradigms and Revolutions
Kuhn was fascinated with scientific revolutions. Einstein's radical transformation of modern physics was one such example of a revolution. But this wasn't what science is all about, according to Kuhn. Instead, it's mostly about day-to-day problem solving.
Einstein disrupted the paradigm of physics, moving from a Newtonian set of assumptions to those set out by his theories of relativity. Now, scientists had a whole new set of tools. After Einstein, many scientists set out on a new cycle of what Kuhn called "normal science."
When conducting normal science, scientists accept a set of shared theoretical beliefs, such as the theories of relativity, and solve all of the remaining puzzles that fall under these beliefs. Scientists solve these puzzles, and pseudoscientists do not.
Kuhn's solution remains controversial, however. Some have argued that conventional pseudoscience, such as astrology, may fall under the broad category of a puzzle solving activity. Other philosophers have built upon Kuhn's and Popper's work, but the demarcation problem remains an open topic of debate in philosophy.
Philosophers have tried to find an adequate solution to the demarcation problem for years. They've made a lot of progress, yet they still haven't nailed down definite criteria that can separate science from pseudoscience or non-science. So why bother?
As pseudoscience creeps into many people's everyday lives, being able to distinguish between scientifically-backed results and pseudoscientific claims has become increasingly important. In philosophy of science, there's been definite headway toward articulating this distinction.
When people are afraid or distrustful of science, scientists need to appeal to outside help to convince skeptics of science's usefulness. And that's where philosophers can help. Philosophers are somewhat removed from the science, and they can deliver some perspective on what science truly is.
Falsifiability and problem solving may be two elements that help to define science, but we likely need more criteria. We're part way there, though, and scientists can use the work of these philosophers to convince non-experts why certain theories have much more justification than others.
For a more thorough explanation of the demarcation problem, check out the Stanford Encyclopedia of Philosophy's articles on Kuhn, Popper, and pseudoscience.
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