Karl Popper
( 1902 – 1994 )
Austrian philosopher, one of the most influential philosophers of science of the 20th century, who helped to establish philosophy of science as an autonomous discipline within philosophy. In political philosophy he was a defendant of liberalism.
He articulated a philosophy of knowledge which he called critical rationalism. This epistemological view holds that empirical knowledge and scientific theories should be rationally criticised and subjected to tests which might disprove them.
Critical rationalists positioned themselves against the emerging relativist approached to knowledge, particularly post-modernist and sociological epistemology. Much of his early work in the philosophy of science deals with the problem of demarcation – the problem of how to distinguish scientific (or empirical) theories from non- scientific theories.
In his The Logic of Scientific Discovery (1935) he introduced the principle of falsifiability as a standard for the evaluation of scientific theories.
Following Hume, he rejected the traditional inductive method in empirical sciences (see Hume’s problem of induction), which holds that scientific hypothesis can be tested and verified by repeated outcomes. The problem with this view is that only an infinite number of experiments and confirmations could prove the theory correct.
Instead, Popper proposed that hypotheses could be verified by the falsifiability criterion – a method, where the aim is to find an exception to the observed rule. The hypothesis is validated by the absence of contradictory evidence.
For example, following the method of induction, we observe swans and come up with the empirical statement “All swans are white”. However, no matter how many white swans you find, you can never be sure that there isn’t a black swan lurking somewhere (and indeed, the exploration of Australasia introduced Europeans to black swans).
There must always be a possibility that a future counter-example could refute the empirical statement —> which makes the theory empirically valid.
The principle of falsifiability is thus not just a method to verify empirical knowledge, but a defining feature of it. According to Popper, the principle can be used to distinguish branches of knowledge as science or pseudoscience.
For example, astrology, moral egoism, metaphysics, Marxist history or Freudian psychoanalysis are not empirical sciences because they do not adhere to the principle of falsiability – for example, a psychoanalyst can find an interpretation of any behaviour in terms of past traumas from childhood. Or, a philosophical egoist (cf. Hobbes) will see any act as essentially stemming from egoistic motivations, no matter how altruistic the act might seem.
According to Popper, any theory of knowledge that can account for all possible events and acts is not an empirical scientific theory, but pseudoscience.
Popper’s political philosophy develops a critique of historicism in favour of an open society and a liberal democracy. His The Open Society and its Enemies (1945) critiques theories that fall into the category of teleological historicism – the view that history unfolds according to universal laws (for example, the philosophies of Plato, Hegel, Marx).
Popper argued that this view often serves as a base for authoritarianism and totalitarianism. He held that (evolving) human knowledge is a factor in the unfolding of history and that no society can predict its future states of knowledge. Large scale social planning is inherently misconceived, and almost always disastrous, because human actions often have unforeseeable consequences.
This view is called historical indeterminism, as it holds that history does not evolve according to laws or principles of necessity.
Just as in his view of science and the falsification principle, so too on a social scale, he advocated for an Open Society, where individuals can criticise the policies of the government, undesirable policies can be abandoned, and political differences are resolved by discussion rather than coercion.