Presentation on theme: "Karl Popper Popper replaces induction with falsification Science is not distinguished from non-science on basis of methodology. No unique methodology specific."— Presentation transcript:
Karl Popper Popper replaces induction with falsification Science is not distinguished from non-science on basis of methodology. No unique methodology specific to science Science consists mostly of problem solving.
Karl Popper All observations are selective and theory laden A demarcation between science and pseudo-science is established by falsification. A theory is scientific only if it is refutable by a conceivable event Every genuine test of a scientific theory is based on an asymmetry between verification and falsification
Sir Karl Popper ( ) Falsification is the idea that science advances by unjustified, exaggerated guesses followed by unstinting criticism. Any "positive support" for theories is both unobtainable and superfluous; all we can and need do is create theories and eliminate error Scientists never actually use induction. It is impossible to verify propositions by reference to experience
Falsificationism (1) Scientific Method Is there a scientific method? What justifies scientific claims to knowledge? Can we distinguish scientific method from non- scientific ways of thinking? (demarcation) Does science progress?
Falsificationism (1) Falsificationism ‘ No criterion of truth ’ : Two Arguments: 2. No Theory/observation distinction: ‘ Here is a glass of water ’ is theory laden In accepting the statement we must accept a significant amount of theory We have only as much justification for accepting the observation statement as we do for the theory
Falsificationism (1) Falsificationism ‘ No criterion of truth ’ : Two Arguments: 2. No Theory/observation distinction: Upshot: we cannot use observation to establish the truth of a theory How can we establish the truth of scientific theories? We can ’ t!
Falsificationism (1) Confirmation and Pseudoscience Good scientific practice: E.g. Einstein ’ s general relativity Conjecture: mass of the sun bends the path of light Actual location Apparent location moon
Falsificationism (1) Confirmation and Pseudoscience Good scientific practice: E.g. Einstein ’ s general relativity Conjecture: mass of the sun bends the path of light If the apparent location of the observed star doesn ’ t shift, the theory is wrong. It will have been refuted. The mark of a scientific theory is whether it can be falsified by observation
Falsificationism (1) Conjecture and Refutation: “ Falsificationists … prefer an attempt to solve an interesting problem by a bold conjecture, even (and especially) if it soon turns out to be false, to any recital of a sequence of irrelevant truisms ” (CR: 231) This gives us: (i) a glimpse of scientific method (ii) a demarcation criterion for science
Falsificationism (1) Scientific method: Scientific theories have deductive consequences They can be falsified but not confirmed. The objective of scientific theorizing is to put forward (bold) hypotheses and then test them in order to falsify them Theories are falsified by basic statements (what is a basic statement?)
Falsificationism (1) Demarcation: Scientific theories are those that can be falsified by basic statements. Good scientific theories do not make themselves immune from falsification by use of ad hoc hypotheses
Falsificationism (1) Progress of Science: Science progresses by eliminating theories that have been falsified? But does it progress? A scientific theory cannot be shown to be true. But some scientific theories do have varying degrees of success. They resist falsification.
Falsificationism (1) “ We must not look upon science as a body of ‘ knowledge ’, but rather as a system of hypotheses which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know that they are ‘ true ’, or ‘ more or less certain ’ or even ‘ probable ’
Kuhn (1) Thomas Kuhn ( ) The Copernican Revolution (1957) The Structure of Scientific Revolutions (1962) History of science not compatible with rationalist view Progress of science not cumulative, driven by the application of a method
Kuhn (1) Thomas Kuhn ( ) The Copernican Revolution (1957) The Structure of Scientific Revolutions (1962) No obvious science/non-science demarcation No context of discovery/context of justification distinction
Kuhn (1) Kuhn ’ s History of Science Two projects: Descriptive — what is the structure of scientific history? Normal science Scientific revolution Explanatory — why does the history of science have this structure? Paradigms
Kuhn (1) 1. Kuhn ’ s History of Science Descriptive Project: Immature Science Normal Science Anomalies Crisis Revolution
Paradigm Diagram old paradigm unexplained observations competing new paradigms one dominant paradigmpuzzle solving incommensurate unsolved puzzles ignored Mopping up operation unexplained observations and alternative interpretation ignored until enough accumulates to overturn current paradigm unexplained observations
Kuhn (1) 1. Kuhn ’ s History of Science Immature Science: No prevailing school of thought Various disparate theories Competition
Kuhn (1) 1. Kuhn ’ s History of Science Normal Science: Stability Determination of significant facts Matching facts with theories Articulation of theories (refinement and extension) “ puzzle -solving ” neither tests nor confirms its theories
Kuhn (1) 1. Kuhn ’ s History of Science Normal Science: Driven by a paradigm (more later): Commonly held set of beliefs, procedures, techniques Agreement upon questions of import Agreement on what counts as a solution Agreement upon standards of evaluation
Kuhn (1) 1. Kuhn ’ s History of Science Anomalies: Not all expectations are borne out Some anomalies lead to further discoveries (e.g. orbit of Uranus) Some simply ignored Troublesome anomalies Challenge key theoretical concepts Resist solutions Inhibit application of theory
Kuhn (1) 1. Kuhn ’ s History of Science Crisis: Weight of accumulated anomalies No agreement on how anomalies are to be dealt with Doubts arise
Kuhn (1) 1. Kuhn ’ s History of Science Revolution: A new paradigm emerges Old Theory: well established, many followers, politically powerful, well understood, many anomalies New Theory: few followers, untested, new concepts/techniques, accounts for anomalies, asks new questions
Kuhn (1) 1. Kuhn ’ s History of Science Revolution: A new paradigm emerges Are old and new theories compared by some rational procedure? “ A new scientific theory does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it ” (Planck)
Kuhn (1) Scientific Revolutions The Ptolemaic model The earth is at the centre of the planetary system Problem: How to explain the retrograde motion of planets
Kuhn (1) Scientific Revolutions The Ptolemaic model The earth is at the centre of the planetary system Problem: How to explain the retrograde motion of planets Earth Deferent Epicycle Planet
Kuhn (1) Scientific Revolutions The Ptolemaic model The earth is at the centre of the planetary system
Kuhn (1) Scientific Revolutions The Ptolemaic Model: Problems: Complexity: epicycle upon epicycle The accumulation of anomalies No clear way forward
Kuhn (1) Scientific Revolutions The Copernican model The sun is at the centre of the planetary system Problem: How to explain the retrograde motion of planets
Kuhn (1) Scientific Revolutions The Copernican model The sun is at the centre of the solar system
Kuhn (1) Scientific Revolutions The Copernican Revolution was not the consequence of an old theory with less ‘ empirical content ’ being replaced by a new theory with more No appeal to reason alone ‘ propaganda ’ To discover how scientific revolutions are effected, we shall therefore have to examine … the techniques of persuasive argumentation within the quite special groups that constitute the community of scientists (SSR: 94)
Kuhn (1) 2. Explanatory Project Two Questions: (i) If this is the course of the history of science, why? (ii) Why aren ’ t competing theories/traditions measured against each other by some rational procedure?
Kuhn (1) 2. Explanatory Project Why is normal science stable? It is conducted wholly within the terms of a disciplinary matrix: questions procedures problems priorities standards of evaluation All are generated by the disciplinary matrix
Kuhn (1) 2. Explanatory Project Why is theory change revolutionary? Theory change is brought about by a ‘ gestalt switch ’ a complete change of world view There is no neutral point from which one can assess theories from two paradigms simultaneously