On the propensity view, the results of experiments are important because they allow us to test hypotheses concerning the values of certain probabilities; however, the results are not themselves part of the probability itself. Popper argues that this solves the problem of single-case probability, since propensities can exist even for experiments that only happen once. Importantly, Popper does not require that these experiments utilize human intervention—instead, nature can itself run experiments, the results of which we can observe.
For example, the propensity theory should, in theory, be able to make sense of claims about the probability that it will rain on a particular day, even though the experimental setup in this case is constituted by naturally occurring, meteorological phenomena.
Popper argues that the propensity theory of probability helps provide the grounds for a realist solution to the measurement problem within quantum mechanics. As opposed to the Copenhagen interpretation, which posits that the probabilities discussed in quantum mechanics reflect the ignorance of the observers, Popper argues these probabilities are in fact the propensities of the experimental setups to produce certain outcomes.
Interpreted this way, he argues that they raise no interesting metaphysical dilemmas beyond those raised by classical mechanics and that they are equally amenable to a realist interpretation. If the experimental setup, however, is expanded to include the results of our looking at the penny, and thus includes the outcome of the experiment itself, then the probability will be either 0 or 1. This does not, though, involve positing any collapse of the wave-function caused merely by the act of human observation.
Instead, what has occurred is simply a change in the experimental setup. Once we include the measurement result in our setup, the probability of a particular outcome will trivially become 0 or 1. This picture becomes somewhat more complicated, however, when we consider methodology in social sciences such as sociology and economics, where experimentation plays a much less central role.
This stands in stark contrast to disciplines such as physics, where the formulation and testing of laws plays a central role in making progress. If the relevant theories are falsified, scientists can easily respond, for instance, by changing one or more auxiliary hypotheses, and then conducting additional experiments on the new, slightly modified theory.
By contrast, a law that purports to describe the future progress of history in its entirety cannot easily be tested in this way. Even if a particular prediction about the occurrence of some particular event is incorrect, there is no way of altering the theory to retest it—each historical event only occurs one, thus ruling out the possibility of carrying more tests regarding this event.
Popper also rejects the claim that it is possible to formulate and test laws of more limited scope, such as those that purport to describe an evolutionary process that occurs in multiple societies, or that attempt to capture a trend within a given society.
This impossibility is because of the holism of utopian plans, which involve changing everything at the same time. This lack of testability, in turn, means that there is no way for the utopian engineers to improve their plans. In place of historicism and utopian holism, Popper argues that the social sciences should embrace both methodological individualism and situational analysis. Scientific hypotheses about the behavior of such unplanned institutions, then, must be formulated in terms of the constituent participants.
For both Popper and Hayek, the defense of methodological individualism within the social sciences plays a key role in their broader argument in favor of liberal, market economies and against planned economies. While Popper endorses methodological individualism, he rejects the doctrine of psychologism , according to which laws about social institutions must be reduced to psychological laws concerning the behavior of individuals.
Popper objects to this view, which he associates with John Stuart Mill, on the grounds that it ends up collapsing into a form of historicism. In order to eliminate the reference to the particular social institutions that make up this environment, we are then forced to demonstrate how these institutions were themselves a product of individual motives that had operated within some other previously existing social environment. This, though, quickly leads to an unsustainable regress, since humans always act within particular social environments, and their motives cannot be understood without reference to these environments.
The only way out for the advocate of psychologism is to posit that both the origin and evolution of all human institutions can be explained purely in terms of human psychology. Popper argues that there is no historical support for the idea that there was ever such as an origin of social institutions.
He also argues that this is a form of historicism, insofar as it commits us to discovering laws governing the evolution of society as a whole. As such, it inherits all of the problems mentioned previously. In place of psychologism, Popper endorses a version of methodological individualism based on situational analysis.
On this method, we begin by creating abstract models of the social institutions that we wish to investigate, such as markets or political institutions.
In keeping with methodological individualism, these models will contain, among other things, representations of individual agents. However, instead of stipulating that these agents will behave according to the laws governing individual human psychology, as psychologism does, we animate the model by assuming that the agents will respond appropriately according to the logic of the situation.
Popper calls this constraint on model building within the social sciences the rationality principle. Popper recognizes that both the rationality principle and the models built on the basis of it are empirically false—after all, real humans often respond to situations in ways that are irrational and inappropriate. Popper also rejects, however, the idea that the rationality principle should be thought of as a methodological principle that is a priori immune to testing, since part of what makes theories in the social sciences testable is the fact that they make definite claims about individual human behavior.
Instead, Popper defends the use of the rationality principle in model building on the grounds that is generally good policy to avoid blaming the falsification of a model on the inaccuracies introduced by the rationality principle and that we can learn more if we blame the other assumptions of our situational analysis , p. More importantly, holding the rationality principle fixed makes it much easier for us to formulate crucial tests of rival theories and to make genuine progress in the social sciences.
By contrast, if the rationality principle were relaxed, he argues, there would be almost no substantive constraints on model building. As mentioned earlier, Popper was one of the most important critics of the early logical empiricist program, and the criticisms he leveled against helped shape the future work of both the logical empiricists and their critics. In addition, while his falsification-based approach to scientific methodology is no longer widely accepted within philosophy of science, it played a key role in laying the ground for later work in the field, including that of Kuhn, Lakatos, and Feyerabend, as well as contemporary Bayesianism.
It also plausible that the widespread popularity of falsificationism—both within and outside of the scientific community—has had an important role in reinforcing the image of science as an essentially empirical activity and in highlighting the ways in which genuine scientific work differs from so-called pseudoscience. Brendan Shea Email: Brendan. Shea rctc. Karl Popper: Philosophy of Science Karl Popper was one of the most influential philosophers of science of the 20th century.
Background Popper began his academic studies at the University of Vienna in , and he focused on both mathematics and theoretical physics. Popper writes: The point is very clear. Auxiliary and Ad Hoc Hypotheses While Popper consistently defends a falsification-based solution to the problem of demarcation throughout his published work, his own explications of it include a number of qualifications to ensure a better fit with the realities of scientific practice.
Popper concludes that, while Marxism had originally been a scientific theory: It broke the methodological rule that we must accept falsification, and it immunized itself against the most blatant refutations of its predictions. Basic Sentences and the Role of Convention A second complication for the simple theory of falsification just described concerns the character of the observations that count as potential falsifiers of a theory.
The basic idea is as follows: For a given statement H , let the content of H be the class of all of the logical consequences of So, if H is true, then all of the members of this class would be true; if H were false however, then only some members of this class would be true, since every false statement has at least some true consequences. The content of H can be broken into two parts: the truth content consisting of all the true consequences of H , and the falsity content , consisting of all of the false consequences of The verisimilitude of H is defined as the difference between the truth content of H and falsity content of H.
This is intended to capture the idea that a theory with greater verisimilitude will entail more truths and fewer falsehoods than does a theory will less verisimilitude. Primary Sources The Open Society and Its Enemies. London: Routledge. The Poverty of Historicism. Originally published as a series of three articles in Economica 42, 43, and 46 The Logic of Scientific Discovery.
London: Hutchinson. Fifth edition Objective Knowledge: An Evolutionary Approach. Oxford: Clarendon Press. Revised edition The Philosophy of Karl Popper.
La Salle, Ill: Open Court. Unended Quest. London: Fontana. Edited by W. Bartley III. Quantum Theory and the Schism in Physics. New York: Routledge. Realism and the Aim of Science. Popper Selections. Edited by David W Miller. Princeton: Princeton University Press. Edited by Mark Amadeus Notturno. All Life Is Problem Solving. Secondary Sources Ackermann, Robert John.
Amherst: University of Mass. Agassi, Joseph. New York: Springer. We should also consider alternative explanations for the results. For example, were the two groups of people equally healthy at the beginning of the experiment? Did the groups differ in other aspects of their behavior that might have influenced the results? Perhaps those in the control group worked in places where they were exposed to more cold viruses. A scientist should not make a firm conclusion about the correctness of a hypothesis until the experimental results have been replicated and most alternate hypotheses have been ruled out.
Correlations It is not always possible to use the experimental method to test a hypothesis. When studying animals in the field or when humans are the subjects, it is difficult to set up an experiment and is often impossible to control the variables. The correlative method offers a second approach to testing hypotheses. A classic example of the correlative approach is the work of John Snow during the London cholera epidemic of Snow hypothesized that cholera was spread by contaminated water, but he had no way to prove it.
So he obtained a map of London and placed a dot at the location of each cholera victim. This eventually showed a spatial correlation between the incidence of cholera and a certain water source. Click the button to read more about this important correlative study. Statistics Statistics are widely used by researchers in both the social and natural sciences. In the experimental method, statistical tests allow the scientist to evaluate whether the results of a single experiment demonstrate an effect of the treatment.
Significance has a special meaning to scientists. If the probability is very low, then than the groups are said to be significantly different from one another. In the experimental method, a significant difference between control and experimental groups means that the experimental treatment had the predicted effect. Statistical Significance Here are the results of an experiment in which the effect of zinc lozenges on duration of colds was tested.
Researchers at the Cleveland Clinic performed the study on a group of employees. Each subject began the experiment within 24 hours of developing cold symptoms. Half the cold sufferers were given zinc lozenges and half placebos in a double-blind design. As you can see from the bar graph, the average recovery time for the control group was 7. It appeared that zinc shortened the average duration of colds by 3 days.
However, without the use of statistics , this conclusion cannot be considered valid. For example, what if only 2 employees were in the experiment? The fact one person recovered 3 days sooner that the other could certainly be due to chance rather than to zinc consumption. If 20 employees had been used, we would be more impressed with these results, but what if the decrease in cold duration was only 1 day or 0. When should we conclude that zinc truly has an effect?
Statistical tests can give us an answer. It is an educated guess about how the world works that integrates knowledge with observation. Everyone appreciates that a hypothesis must be testable to have any value, but there is a much stronger requirement that a hypothesis must meet.
A hypothesis is considered scientific only if there is the possibility to disprove the hypothesis. A hypothesis or model is called falsifiable if it is possible to conceive of an experimental observation that disproves the idea in question.
That is, one of the possible outcomes of the designed experiment must be an answer, that if obtained, would disprove the hypothesis. The statement is intentionally vague. You can use it freely with some kind of link , and we're also okay with people reprinting in publications like books, blogs, newsletters, course-material, papers, wikipedia and presentations with clear attribution.
Menu Search. Menu Search Login Sign Up. You must have JavaScript enabled to use this form. Sign up Forgot password. Leave this field blank :. Search over articles on psychology, science, and experiments. Search form Search :. Reasoning Philosophy Ethics History. Psychology Biology Physics Medicine Anthropology. Martyn Shuttleworth , Lyndsay T Wilson Karl Popper's Basic Scientific Principle Falsifiability, according to the philosopher Karl Popper, defines the inherent testability of any scientific hypothesis.
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