Karl Popper's Critical Rationalism: Definition & History

Instructor: Gaines Arnold
How do scientists decide if the theory they put forward is reliable or not? In this lesson, psychologist Karl Popper and his theory of critical rationalism is defined and the reason behind creating the theory is discussed.

Karl Popper Biography

What was it like for anyone, whether they were of an oppressed class or not, to live through the rise of national socialism (aka Nazism) during the 1920s and 1930s? Many people, due to the extreme poverty and German degradation brought on by Allied decision-making after World War I, were happy to see the promise of Germany's return to prominence. However, there were others, many intellectuals included, who believed that falling into fascism was dangerous and counterproductive.

One of these intellectuals, of Jewish heritage, was Karl Popper (1902-1994). He trained as an elementary school teacher and then as a psychologist, but his primary contributions were to the field of general science. As the Nazis were coming to power, the Austrian-born Karl Popper tried to gain a position in academia prominent enough that his ancestry would not matter. However, because he opposed the rise of fascism and worked for democracy in his country, he was forced to leave Austria for England, where he did the majority of his work.

Karl Popper

The Basis of Popper's Scientific Ideas

Popper chose not to confine himself to the field of psychology because he felt it was too restrictive. His ideas were for the scientific community at large, society, and the political realm. He delved into all three after he began questioning the popular ideas of his time.

Scientific inquiry was based on the scientific method then as it is today. The researcher starts with a question, conducts research to determine a more exact question, forms a hypothesis, and then experiments (using empirical, or observational, methods) to determine a conclusion. Unfortunately, most of these conclusions are theories rather than facts. Popper realized that it was difficult to determine facts in the social sciences, but he also realized that a number of theories could be disproven if research were conducted differently.

Critical Rationality

In order to conduct research correctly, Popper believed that the scientist had to be critical. Empiricism, or observation, is the primary means social scientists use in research. They set conditions for a test; then they observe what happens. However, observation is passive. There has to be some thought applied to truly understand what is being observed. Of course, this always happens to some extent, but scientists tend to believe the evidence they see; they are rarely completely critical.

Critical rationality is the belief that all answers have to be examined with an eye toward their failure. The classic example is making a statement such as 'All swans are white,' which is disproven by a black swan. Popper didn't believe that theories were the end of research; they were the beginning. The process, then, is:

  • a theory is formed based on an empirical research study
  • further tests are conducted in an effort to refute the original claim
  • if the theory as a whole is disproved, then it is false
  • if the theory is partially disproved, then it is refined

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