Karl Raimund Popper 1902-1994 “Our knowledge can only be finite, while our ignorance must be necessarily infinite” -Karl Popper Marette Abdelmaseh

Life Born in Vienna, Austria in 1902 to a prestigious family. Dropped out of secondary school in 1918 and attended classes at the University of Vienna as a guest student Considered himself a communist until he witnessed several students being killed by police in a demonstration. He then became a social liberalist. Worked with a cabinet maker; wanted to establish a daycare facility; joined the university as a regular student from 1922-1928 and received: A primary school teaching certificate Qualification to teach mathematics and physics in secondary school Doctorate of Psychology Published “The Logic of Scientific Discovery” in 1934 Died in 1994 due to cancer complications

The Logic of Scientific Discovery Epistemology Reputation as an original contributor to the philosophy of science. Skepticism Evaluated the “Problem of Induction” Science should adopt a method of Falsifiability

The Problem of Induction Two types of statements exist:  singular existential statements: assert the existence of some particular thing universal statements: statements that categorize all instances of something, Inferences are inductive if they go from singular statements to universal statements. Generalizing Presupposing Cannot progress from “ All observed A’s are B” to “All A’s are B” or “A has always occurred” therefore “A will always occur” Therefore, induction provides no certainty, only reliability or probability Principle of Induction: there are similarities/patterns in the world This lead to Popper’s idea of Falsification

School of Thought: Falsification No number of confirming observations can verify a scientific theory HOWEVER a single contradictory observation can invalidate a scientific theory The term “falsifiable" does not mean something is made false, but rather that, if it is false, it can be shown by observation or experiment. Popper’s philosophy of science is therefore concerned with falsification rather than verification as most scientists are Popper then established the branch of epistemology called “Critical Rationalism” Scientific theories and any other claims to knowledge can and should be rationally criticized, and if they have empirical content, can and should be subjected to tests which may falsify them.

Science and Nonscience The criterion of demarcation: a genuinely scientific hypothesis must be empirically falsifiable Logical Positivists: accumulated experience ↓ scientific hypothesis ↓ verification by factual observation Critical Rationalist : hypothesis/theories ↓ testing by experiment to see if predications are falsified by experience

“In so far as a scientific theory speaks about reality, it must be falsifiable, and in so far as it is not falsifiable, it does not speak about reality” -Karl Popper

Knowledge Issue Level Good   Good If in order for a theory to be valid or scientific it must be falsifiable, how (if at all) can a valid theory ever be confirmed as true? Intermediate What role does inductive reasoning have in determining the falsifiability of a theory? Poor Is it possible to find any truth through inductive reasoning? Not a knowledge Issue Are all swans white? /Will the sun rise tomorrow? Real life Situation I saw a white swan in the pond. / The sun rose this morning.

Swans are White

Real Life Situations Generalizations Swans are white. There are an endless amount of observed white swans in the world. This leads to the inductive theory “Swans are white” However, once a black swan is observed, this theory is invalid/falsified

Real Life Situations Presupposing The sun rises everyday. The sun has risen everyday since the beginning of time. This leads to the inductive theory “The sun will continue to rise everyday” This theory can be assumed to be true until the given day that the sun does not rise at which time the theory is falsified.

Counter Arguments When a theory is falsified, a new theory is created as a result. Example: When the theory “All swans are white” was falsified, the theory “Not all swans are white” was created. Can this theory be considered true, or must it also be subject to falsification? Falsification itself is a theory. Must falsification be falsifiable?

Counter Aruguments The Quine-Duhem thesis argues: “it's impossible to test a single hypothesis on its own, since each one comes as part of an environment of theories. Thus we can only say that the whole package of relevant theories has been collectively falsified, but cannot conclusively say which element of the package must be replaced”. Example: the discovery of the planet Neptune: when the motion of Uranus was found not to match the predictions of Newton's laws, the theory "There are seven planets in the solar system" was rejected, and not Newton's laws themselves. 

Counter Arguments There are some hypotheses that cannot be falsified Example: “For every metal, there is a temperature at which it will melt." The hypothesis cannot be falsified by any possible observation, for there will always be a higher temperature than tested at which the metal may in fact melt, yet it seems to be a valid scientific hypothesis How can one conclude that the theory has been falsified and that the evidence is not simply faulty?

Synthesis Popper worked in the branch of epistemology, establishing his own facet called “Critical Rationalism” His book “The Logic of Scientific Discovery” addresses several of the main concepts of his epistemology including the problem of induction, the principle of induction, falsification and the criterion of demarcation Popper believed that the correct approach to science was falsification rather than verification. A scientific theory is not valid unless it is falsifiable According to Popper, inductive reasoning holds no ground as demonstrated by falsification. No number of individual instances is sufficient to create a generalization.

Unresolved Questions Are theories that cannot be scientifically verified or falsified, such as the belief in God ultimately neither true or false? The theory simple exists with no way to scientifically investigate the truth or implications of the theory. How can perception be falsified? If I see a black board and I perceive that it is black, how can this be falsified? How about emotion? There are certain aspects of knowledge that cannot be scientifically studied.

“Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory or the problem which it was intended to solve.” - Karl Popper

Works Cited Popper, Karl R. The Logic of Scientific Discovery. New York: Harper & Row, 1968. Print. Thorton, Stephen. "Karl Popper." (Stanford Encyclopedia of Philosophy). N.p., 13 Nov. 1997. Web. 25 Feb. 2013. Popper, Karl R. Objective Knowledge: An Evolutionary Approach. Oxford [Eng.: Clarendon, 1979. Print. Sion, Avi. "The Principle of Induction." The Logician. N.p., n.d. Web. 03 Mar. 2013. Sion, Avi. "Hume's "problem of Induction"" The Logician. N.p., n.d. Web. 03 Mar. 2013. Yuksel, Edip. "Popper's Theory of Epistemology: A Perpetual Falsifiable Journey Towards Truth." Yuksel. N.p., n.d. Web. 03 Mar. 2013.