63 pages • 2 hours read
Karl PopperThe Logic of Scientific Discovery
Nonfiction | Book | Adult | Published in 1934A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Part 1Chapter Summaries & Analyses
Part 1: “Introduction to the Logic of Science”
Part 1, Chapter 1 Summary: “A Survey of Some Fundamental Problems”
The Problem of Induction
Popper opens by asserting that the logic of scientific discovery requires a universal understanding of procedure. Empirical science utilizes the senses to guide experimentation. Popper argues against the inductive methods used in empirical sciences that develop definitive conclusions, called universal statements, based upon evidence. Logic dictates that universal statements can never be fully justified because there is always the possibility that they may be disproven. Popper utilizes the example of swans to illustrate this idea. One may observe several swans, all of which are white, and conclude that all swans are white. However, the existence of one black swan challenges this universal statement. Popper calls this “the problem of induction” (28). He asserts that no one can state a definitive conclusion because new evidence always has the possibility of falsifying a claim.
Inductive scientists rely upon a principle of induction to establish certain truth. They argue that eliminating inductive logic from the scientific method would mean stripping scientists of their ability to present clear theories and, therefore, put them at equal status with false, imagined ideas. Popper proposes, however, that an adherence to inductive logic is what solidifies scientific thought into a realm of the imaginary. Concepts like “probability” and “reliability” present a false notion of what can be known through scientific experimentation. Popper advocates, instead, for a deductive method that emphasizes continual testing.
Elimination of Psychologism
Popper opens this section by separating his approach to logic in science from the epistemological ideas about where knowledge and ideas come from. He suggests that where a hypothesis or an idea comes from is irrelevant to the methodology of scientific discovery. Popper is more interested in whether a scientific statement can be justified or tested. He proposes that ideas will always have “an irrational element” that cannot be fully understood through philosophical inquiry.
Deductive Testing of Theories
Popper suggests that an idea begins with developing a logical deduction that is neither proven nor taken as true. This deduction is compared to other singular scientific statements. He then outlines four ways of testing a theory. The first way of testing begins with comparison; this method attempts to see if there are inconsistencies among ideas. The second questions the logic of the theory and its scientific soundness. The third compares the theory to other theories to determine whether it would advance scientific inquiry and understanding. The fourth tests the theory using empirical approaches. The purpose of this last step is not to prove a theory but to determine whether it holds up under practice. This final step has two outcomes: It either temporarily verifies the theory or falsifies it.
The Problem of Demarcation
Advocates for inductive logic argue that the removal of inductive reasoning separates epistemological science from empirical science. Popper proposes that this is precisely the reason for making the distinction. However, attempts at demarcation—establishing a set of criteria to draw a line between science and non-science—further add to the problem with inductive logic. Science is distinguished from non-science because it does not set out to prove an idea; instead, it is used to shed light on falsity.
Experience as a Method
In this section, Popper attempts to establish a definition for empirical science. He argues that an effective empirical approach must rely upon three requirements. First, it must be synthetic, or possible. Second, it must align with the criteria set forth in the next section. Third, it must stand up to testing. This testing is experience.
Falsifiability as a Criterion of Demarcation
Popper argues that there is no such thing as inductive logic; scientific theories can never be fully verified. Therefore, the scientific method must have a different aim. Empirical science should focus its attention on falsifiability; it should attempt to refute the idea through experience. No idea can be verified because a new piece of evidence or experience may one day falsify it.
The Problem of the “Empirical Basis”
Empirical science must devote itself to singular statements rather than non-strict universal statements. Popper points to perceptual experience as one problem with empirical basis; rather than applying robust testing, perceptual experience justifies statements through other statements. Popper suggests that this is another example of the need for demarcation and the separation of science from philosophy and psychology.
Scientific Objectivity and Subjective Conviction
At the beginning of this section, Popper defines objectivity as an attempt to verify knowledge. This, as he has established, cannot be done. Subjectivity—feelings and convictions—can also never lend justifiability to a scientific statement. He, therefore, embraces a different approach to objectivity. This definition refers to a lack of favoritism for an idea; he suggests that this form of objectivity relies upon “inter-subjective testability” (47). Within this definition, the scientist embraces that the statement can be tested in many ways and that any principle may be falsified.
Part 1, Chapter 2 Summary: “On the Problem of a Theory of Scientific Method”
Why Methodological Decisions are Indispensable
Positivists, or those who embrace inductive reasoning, view empirical science as a collection of statements that can be verified. Popper views empirical statements as influenced by criticism. He believes it is the role and purpose of the scientist to apply immense pressure to a scientific statement. Just as no statement can be proved, it can also never be conclusively disproved. Instead, scientists must embrace the falsities of results by imposing a scientific system of methodology that adheres to specific norms.
The Naturalistic Approach to the Theory of Method
Popper argues that positivists do not want a logical scientific methodology; they want to be able to attack philosophical problems as puzzles that, ultimately, determine meaning. New philosophical schools erase the ideas of previous schools while other philosophers defend ancient, traditional philosophical thought. Popper proposes that philosophical questions must be treated with a different methodology than science and that the two should not be seen as interchangeable. They require two different sets of methodology. Philosophy utilizes a naturalistic methodology, but this approach also produces inconsistencies. Inductive logic, while useful in philosophy, has no place in the scientific method; it merely clouds the process.
Methodological Rules as Conventions
In this section, Popper outlines the rules of his proposed methodology, which he refers to as “conventions.” The first rule is that science is ongoing; it has no end. Nothing is ever verified with finality. The second rule is that a tested hypothesis cannot be abandoned unless it is replaced by a better hypothesis or is falsified. These rules are applied and enforced to secure demarcation between science and non-science.
Part 1 Analysis
Like many philosophical works, Popper opens his argument as a reaction to previous assumptions in epistemology. The field had long been divided. Rationalists argued that humans acquired knowledge through their ability to reason. Popper’s separation of his approach to scientific methodology from epistemology and psychology marks a distinction between his work and other philosophers. The history of scientific philosophy is dominated by various camps asserting their own theories about how humans understand and acquire knowledge and ideas.
In the fourth century, Plato offered his explanation through the narrative of “The Slave Boy Experiment.” In his work Meno, Plato asks for an example of how humans tap into their logical reasoning. A small, enslaved boy is present with a series of basic geometry problems, which he answers correctly. For example, he is asked to double the area of a square; the boy succeeds by doubling the length of the sides of the square. Plato uses this narrative to suggest that the boy has tapped into an innate knowledge. Rationalists argue that humans acquire knowledge through their ability to reason; this logic comes from a wellspring of universal truths that are intrinsic to the human condition.
Then, in the 17th century, John Locke provided a different explanation. He denied the existence of this innate knowledge and argued, instead, that human understanding is born from experience. Locke argued that humans reach an understanding of universal laws through the senses. In the case of the boy described by Plato, empiricists believe that the boy likely developed his own geometrical theories over time as he encountered daily geometrical problems. An example of this would be a baby playing with a board with a series of shaped holes cut into it. The baby has been given different shaped blocks to place in the holes; there is a round shape for the round hole and a square shape for the square hole, etc. The baby does not, at first, know how to fit each block into each hole. Over time and with practice, however, the baby learns that the shapes must match the shape of the holes. The baby’s sense-experience helps it to acquire knowledge about shape and space. Locke pioneered this new wave of epistemological thought that emphasized the role of experience in understanding. This opposition to rationalism was called “empiricism.” David Hume carried this work forward and applied it to the scientific realm while Immanuel Kant found a way to reconcile both the need for logic and experience in epistemology. Popper opens The Logic of Scientific Discovery with the weight of this history informing his thesis.
Popper recognizes that both experience and logic play a role in the scientific method. However, he also identifies a major problem with empiricist approaches that pair experience and observation with the verifiability of inductive logic. Popper calls those who use inductive logic “positivists.” This group tests theories for the purpose of authenticating scientific theories. Popper argues that this form of reasoning leads to pseudoscience. This is The Problem with Inductive Logic. If an experiment seeks to verify its claim, then all observations can be taken as affirmations of the theory’s validity. Popper’s use of the swan illustration has become synonymous with his work. The observation of many white swans would lead inductivist scientists to make the claim that all swans are white. However, the existence of a single black swan falsifies that claim. This, Popper asserts, must be the purpose of all scientific inquiry: The Aim of Falsifiability.
Popper is highly critical of what he calls “psychologism,” which refers to the field of psychoanalysis pioneered by Sigmund Freud. Popper maintains that Freud and others in the field of psychologism utilize inductive logic. He believes that Freud uses observation to justify theories and that this approach allows for the manipulation of data to verify a claim. Popper advocates for the Demarcation of Science and Non-Science. For the philosopher, inductive reasoning is the hallmark of non-science, or pseudoscience. He applies this same criticism to metaphysics and any other field that utilizes positivism. Astrology, widely regarded as pseudoscience, provides an example of Popper’s argument. A man reads an astrological report in a newspaper that declares that he will meet a stranger with whom he will develop a relationship. As the man goes about his day, he wonders if each new person he encounters is the person the report was describing. Because he is looking at each person with attraction in mind, he is more open to engaging with these strangers and making a connection. He meets a person at a coffee shop and engages in a dialogue; later, they exchange numbers. The man goes home and is confident that the report he read must have been true; after all, he had started a new relationship that day. This example illustrates how inductive logic can affirm almost any idea. Because the man sought to affirm the report, he found a way to make it true.
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