This blog post explains the difference between pseudoscience and science, focusing on Popper’s theory of falsifiability to clarify how scientific theories differ from pseudoscience.
In everyday life, ‘pseudoscience’ refers to things that appear similar to science at first glance but are not actually science—that is, false science. For example, when someone blindly believes in blood type or zodiac personality theories, it is often criticized as ‘pseudoscience’. However, it is rare to call the geocentric theory, which disappeared with the advent of the heliocentric theory, ‘pseudoscience’. Thus, the distinction between science and pseudoscience is highly ambiguous. Now, let’s examine the efforts of Karl Raimund Popper and subsequent researchers regarding this ambiguous distinction.
To distinguish pseudoscience from science, we must first understand what pseudoscience is. Popper used the term ‘pseudo-science’ and clearly distinguished between false scientific theories and pseudoscience. The difference between a false scientific theory and pseudoscience is analogous to the difference between a ‘false statement’ and a ‘meaningless utterance’. Generally, a false statement appears meaningless, but sometimes its negation can be true. In contrast, meaningless expressions are not false statements but expressions that are inherently devoid of meaning. The negation of such meaningless expressions is also meaningless. That is, the negation of pseudoscience remains merely pseudoscience. Flawed scientific theories can be proven false through falsification but are still considered science. Conversely, pseudoscience, being inherently unfalsifiable, cannot be distinguished as true or false, making it difficult to include within the category of science.
Popper proposed a theory’s ‘falsifiability’ as the criterion for evaluating its scientific status. Falsifiability indicates whether a theory can be proven false, and a true test of a theory is an attempt to falsify it. A theory that cannot be falsified is unscientific, considered a fatal flaw. Popper named this the ‘criterion of demarcation’.
Popper argued that theories like astrology, Marxist history, Freud’s psychoanalysis, and Adler’s individual psychology were pseudoscience because they lacked falsifiability. Astrology evaded falsification through vague statements, while Marxism, though initially amenable to prediction and verification, later lost its falsifiability by reinterpreting the theory to fit the evidence. The theories of Freud and Adler were structured from the outset to be impossible to refute, making it difficult for them to attain scientific status. Popper defined pseudoscience as theories that are either impossible to falsify or deliberately evade falsification.
Despite Popper’s efforts, the method for clearly distinguishing science from pseudoscience remains unclear. Popper’s criterion of falsifiability is also imperfect, and later researchers have pointed out its limitations. For example, it has been argued that some propositions, such as probabilistic statements, cannot be assessed for falsifiability. Therefore, applying Popper’s theory to modern pseudoscience is not always appropriate.
So, how do we use the term ‘pseudoscience’ in everyday life? As mentioned earlier, ‘pseudoscience’ is generally used to refer to theories or claims that are not science. However, this is not strictly correct usage. Pseudoscience refers to theories whose truth or falsity cannot be determined. What most people call ‘pseudoscience’ is often actually scientifically proven falsehoods. For this reason, distinguishing between pseudoscience and false science is important.
For example, the works of Emoto Masaru are often called pseudoscience, but his claims are actually closer to false science. His theory that water can distinguish between good and bad lacks sufficient evidence to prove it, and the experimental results he presented were merely manipulated to fit his desired conclusions. Therefore, this theory is not pseudoscience but clearly false science.
Isaac Asimov once stated, “All theories are either true or false, but the ones closest to the truth are the incomplete ones.” I believe pseudoscience is closer to an ‘incomplete theory’ than to false science providing misinformation. Pseudoscience, where truth and falsehood coexist, is a theory with equal potential to be true or false. It simply lacks a method for verification. Consider astrology and Freud’s psychoanalysis, which Popper classified as pseudoscience. Astrology was a theory open to refutation and falsification. However, astrology researchers refused to accept evidence proving it false and instead restructured the theory to suit their desires. Consequently, astrology, initially scientific, later became a false science. In contrast, Freud’s psychoanalysis remains unfalsified and leaves room for refutation. I believe such theories are the true pseudoscience.
The public criticizes theories lacking scientific basis or credibility as ‘pseudoscience’. However, most targets of criticism are false science that manipulates experimental results or fails to provide adequate evidence. Using the term ‘pseudoscience’ to criticize such false science is inappropriate.
