14 3.2 Characterizing Scientific Progress

3.2.1 Popper: Falsifiability and Science

Karl Popper (1902 – 1994) was an Austrian philosopher of science who maintained that our knowledge of the natural world cannot grow by confirming scientific hypotheses but only by using experience and observation to falsify alternative theories. In the last section we saw the logical-argument model to support this assertion. Requiring falsifiability for theories (that a theory must entail the possibility of being empirically disproven), led Popper to distinguish between:

  • “science” – where theories can be falsified empirically, and
  • “pseudo-science” where theories do not predict any falsifiable results.

A well known example of Popper’s reasoning for this distinction is his comparison of Einstein’s theory of general relativity with Freud’s theory of psychoanalysis. Popper believed general relativity to be scientific and psychoanalysis to be pseudoscience. His interpretation lies in the testability of the two theories. He held that general relativity makes predictions that provide opportunity for falsification through experiments and observation; psychoanalysis, on the other hand, can come up with an explanation for any behavior, and is thereby not falsifiable. The upcoming video explains the concept of falsification in Karl Popper’s own words from his work Conjectures and Refutations, originally published in 1963.


A supplemental resource is available (bottom of page) on the concept of falsifiability.


Suppose a promising theory cannot be tested by current methods of experiment, or even by anticipated methods — for example, particle-physics theories with entities too small to observe, or cosmological theories about space where predicted values are too large to be observed. Do you think such endeavors still count as “science?” Explain your position.

Then, consider the question of the cause of global warming. While rising sea levels seem to confirm that warming is real, some hold that the cause of warming cannot be verified to be human activity. Are such claims legitimate reason to redirect scientific investigations?

Essentially, do you think science requires immediate possibility of falsification?

Note: Submit your response to the appropriate Assignments folder.

3.2.2 Scientific Theories

Given the two version of scientific methods we looked at in the last sub-unit, how do scientific investigations become “laws” or theories?

Induction and Generalization

The generalization ‘All polar bears are white’ is arrived at by an inductive argument. The more evidence in support of the conclusion the stronger the argument. Enough evidence in support of a generalization moves it from being a simple correlation of observations, to a law-like regularity, sometimes referred to as “nomic” regularity.

Hypothetical Method

When a hypothesis has gathered strength from repeated confirmation of expected result (through tests, observations) and has failed to be falsified (no findings contrary to expected result), it may become accepted as a theory. Hypothetical reasoning produces logical certainty only in the case of falsification; a form of valid deductive argument falsifies the hypothesis. A hypothesis that is not falsified cannot be validated (proven true) with absolute certainty; its confirmation, through repeated occurrence of expected results, attests to its strength and high probability of certainty, but not logical certainty, or truth by necessity. So confirmation of a theory, too, can be seen as inductive.

Strong hypotheses may receive tentative acceptance, sometimes even before being confirmed or disproved. Tentative acceptance is based on a variety of factors that boost their strength, including these:

  • Adequacy – The extent to which the scope of a hypothesis fits the facts it is intended to explain. If one hypothesis accounts for the data with greater accuracy, then that hypothesis is more adequate than another. A hypothesis is inadequate to the extent that facts exist for which the hypothesis cannot account.
  • Internal coherence – The extent to which the ideas or terms in a hypothesis are rationally interconnected.
  • External consistency – The extent to which a hypothesis agrees (or does not disagree) with other, well-confirmed hypotheses.
  • Fruitfulness – The extent to which a hypothesis suggests new ideas for future analysis and confirmation.
  • Simplicity – The extent to which a hypothesis is easy to understand or explain. Ockham’s Razor expresses the merit of simplicity. When more than one explanation is availablethe simpler one is preferable.

A hypothesis may be accepted as a theory if it is the best explanation currently available for the question/problem at hand. But is it still a “theory” which may be replaced by a better one at some point.

3.2.3 Kuhn: Scientific Revolution

Before we move to the idea of “scientific revolution” from a Philosophy-of-Science perspective, it is important to keep in mind that the designation “The Scientific Revolution” is commonly used in reference to a period in modern Western history – the 16th, 17th, and 18th centuries. During that time, many new discoveries occurred and a major shift took place in how knowledge was sought.


A structured 10-minute TED video explains five pivotal events of the scientific revolution: Scientific Revolution [CC-BY-NC-ND]

Thomas Kuhn (1922 – 1996) was an American physicist and philosopher of science, He shook up some long-standing conceptions of how science progresses in his workThe Structure of Scientific Revolution (1962, 1970). Kuhn made the point that scientific progress is characterized by discontinuity. Long periods of “normal research” occur within the structures of the current theoretical paradigm. These longer periods of scientific activity are interrupted by brief periods of scientific revolution that shift or change the formerly prevailing paradigm to a new one.

A paradigm is a central model or template, along with its background assumptions, within which science works. Procedural paradigms control study of the natural world during periods between scientific revolutions.

Kuhn saw science as a social activity in which a community of scientists accept a paradigm consisting of theories and methods of discovery and proof. When scientific revolutions periodically overturn the current paradigm and establish a new one, older scientists try to hold on to the old theories and resist the new paradigm. Kuhn suggests that the new paradigm is not necessarily more true than the old.

Kuhn disagreed with the view held by both induction-generalization and falsification advocates that science grows at a measured and steady pace. Instead, he believed that science makes big leaps forward during the periods of major revolutions.

A supplemental resource is available (bottom of page) on Kuhn’s philosophy.

Kuhn’s Sustained Impact

In 2012, the 50th anniversary of The Structure of Scientific Revolution brought the publication of a 50th anniversary edition and promoted a flurry of journal articles and other media coverage about Kuhn’s influence. These retrospective accounts were essentially tributes to Kuhn’s contributions and the revisions he inspired to the thinking of his time; they also pointed out controversies and concerns related to Kuhn’s work.

John Naughton’s article “Thomas Kuhn: the man who changed the way the world looked at science” in The Guardian (August 2012)1 is an upbeat 50-years-later look at The Structure of Scientific Revolution and provides an engaging account of Thomas Kuhn’s life, work, and contributions. (The bibliographic footnote at the end of this section includes a link to the article.) Fundamental concepts of paradigm shift and scientific revolution are explained without complicated jargon, along with some of the reactions to and implications of Kuhn’s work. Naughton points out that “incommensurability” — the inherent impossibility for accurate comparisons between the old paradigm and the new one — is problematic and creates reservation about the overall rationality of science.

David Kaiser’s tribute to Kuhn “In retrospect: The Structure of Scientific Revolutions” in the journal Nature (April 2012)2 expresses deep appreciation of Kuhn’s contributions as well as candid evaluation of issues that have prevailed in the past 50 years. Kaiser also cites the matter of incommensurability, and he speaks of the slippery nature of “paradigm” — the concept itself — as a word with too many uses and “saddled with too much baggage.” Kaiser says:

Perhaps the most radical thrust of Kuhn’s analysis, then, was that science might not be progressing toward a truer representation of the world, but might simply be moving away from previous representations. Knowledge need not be cumulative: when paradigms change, whole sets of questions and answers get dropped as irrelevant, rather than incorporated into the new era of normal science.

Matthew C. Rees’ article “The Structure of Scientific Revolution at Fifty” New Atlantis (Fall 2012)3 also points out that paradigm shifts from one worldview to another (rather than a “progressive accumulation of knowledge”) have been seen as “a denial of the existence of absolute truth.” Does dropping one set of apparent truths (the old paradigm) to adopt a new set of truths (new paradigm) question the possibility of absolute truth? From an epistemological viewpoint, does Kuhn’s overall theory of knowledge become skeptical? These are interesting questions!

However, there is no across-the-board agreement that a new paradigm, by definition, really does discard everything about the one it replaces. In his Nature article, David Kaiser comments on this: “The field of science studies has changed markedly since 1962. Few philosophers still subscribe to radical incommensurability…” Rees too points out that The Structure of Scientific Revolution, while intended by Kuhn as speculative, took up a life of its own life, complete with exaggerated interpretations.

In pointing out another criticism of Kuhn’s work, Matthew Rees cites an interesting question about the aim of science that straddles the fields of Philosophy of Science and Ethics:

Kuhn was also criticized for building a wall between basic science (that is, science conducted for its own sake) and applied science (that is, science aimed at achieving specific, often socially important, goals). Against Bacon’s dictum that the proper aim of science is “the relief of man’s estate,” Kuhn argued that scientists in the “normal” stage must ignore “socially important problems” and should instead just focus on solving puzzles within the paradigm.


What do you think is the aim of science? Do you think science is about answering questions for their own sake? Or is it the job of science to direct its efforts and resources toward solving society’s problems? Using examples may help you argue your point.

Note: Post your response in the appropriate Discussion topic.

Complete the Unit Test by the date on the Schedule of Work.

Supplemental Resources


The first four-minutes of this video are of particular interest. Falsifiability: One Key to Critical Thinking


Internet Encyclopedia of Philosophy (IEP) Scientific Change Start with Section 3.a. “Kuhn, Paradigms and Revolutions”, continue on thru part i., “Key Concepts in Kuhn’s Account of Scientific Change.”


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