Karl Popper

Karl Popper was an Austrian–British philosopher best known for his contributions to the philosophy of science, political philosophy, and epistemology. He is widely regarded as one of the most influential philosophers of the twentieth century, particularly for his critique of scientific certainty and his formulation of falsification as the demarcation criterion between science and non-science. Popper’s work emphasised critical rationalism, intellectual openness, and the rejection of dogmatism in both scientific inquiry and political life.

Background and Early Life

Karl Popper was born in 1902 in Vienna, then part of the Austro-Hungarian Empire, into a middle-class family of Jewish origin. He was raised in an intellectually rich environment, with access to a large personal library that exposed him to philosophy, science, and classical literature from an early age. Popper initially trained as a schoolteacher and studied mathematics, physics, and philosophy at the University of Vienna. The political turmoil and ideological conflicts of interwar Europe strongly shaped his intellectual outlook, particularly his opposition to totalitarianism.

Intellectual Context and Influences

Popper’s early thinking developed in response to both logical positivism and Marxism, two dominant intellectual movements of his time. While he admired the scientific ambitions of the Vienna Circle, he rejected their emphasis on verification as the basis of scientific knowledge. At the same time, his disillusionment with Marxism stemmed from what he saw as its immunity to criticism. These experiences led Popper to emphasise fallibility, criticism, and openness as essential features of genuine knowledge.

Falsification and the Philosophy of Science

Popper’s most significant contribution to the philosophy of science is the principle of falsification. He argued that scientific theories cannot be conclusively verified but can be rigorously tested and potentially falsified. According to Popper, a theory is scientific only if it makes risky predictions that could, in principle, be proven false by observation or experiment.
This view challenged the traditional inductive model of science, which assumes that repeated observations confirm universal laws. Instead, Popper proposed that science progresses through bold conjectures and systematic attempts at refutation. When a theory withstands falsification, it is not proven true but is tentatively accepted until a better explanation emerges.

Demarcation Between Science and Pseudoscience

Popper introduced falsifiability as a solution to the demarcation problem, the challenge of distinguishing science from non-science or pseudoscience. He argued that theories such as astrology and certain forms of psychoanalysis fail to qualify as scientific because they can accommodate any possible observation and are therefore unfalsifiable. In contrast, theories like Einstein’s theory of relativity were praised by Popper for making precise predictions that exposed them to potential refutation.

Critical Rationalism

Popper’s broader epistemological position is known as critical rationalism. This approach rejects the search for absolute certainty and foundational knowledge, instead advocating continual critical scrutiny of all claims. Knowledge, according to Popper, grows through the elimination of errors rather than the accumulation of justified beliefs. This view applies not only to science but also to philosophy, ethics, and social theory.

Political Philosophy and the Open Society

Popper’s political philosophy is most clearly articulated in The Open Society and Its Enemies (1945). Written during the Second World War, this work presents a strong defence of liberal democracy and a critique of totalitarian ideologies. Popper criticised philosophers such as Plato, Hegel, and Marx for promoting historical determinism and utopian social planning, which he believed justified authoritarian rule.
He advocated the concept of the open society, characterised by democratic institutions, individual freedom, and the capacity for peaceful reform. Popper argued that political systems should be judged not by their ideal goals but by their ability to correct mistakes and prevent large-scale harm.

Piecemeal Social Engineering

In contrast to revolutionary or utopian approaches to social reform, Popper proposed piecemeal social engineering. This method emphasises gradual, evidence-based reforms that can be evaluated and corrected if they fail. By limiting the scale of social experiments, societies reduce the risk of catastrophic consequences. This idea reflects Popper’s broader commitment to fallibilism and critical testing in both science and politics.

Academic Career and Later Life

Popper emigrated to New Zealand in 1937 to escape Nazism and later moved to the United Kingdom, where he became a professor at the London School of Economics. His academic career brought him international recognition, and he influenced generations of philosophers, scientists, and social theorists. In 1965, he was knighted for his contributions to philosophy.