The Scientific “Method” and Its 20th Century Critics: Popper & Kuhn

1. The Scientific “Method” and Its 20th Century Critics: Popper & Kuhn

2. Today’s Class • Hume’s Problem of Induction • What constitutes the distinction between science and non-science for Popper? • What constitutes the distinction between science and non-science for Kuhn?

3. Hume’s Problem of Induction • Hume asked: What justifies are faith in inductive reasoning? • Good inductive evidence? This just begs the question. • We just seem to assume what he called the “uniformity of nature” (UN) principle • The Historian Lynn White Jr. argued that this basic belief of scientists is a legacy of Judeo-Christianity (an unquestioned assumption taken on faith)

4. Popper on How to Distinguish Between Science and Non-Science • For Popper, science is the activity of evidence gathering for the corroboration of tentatively held theories about how the universe operates • All truly scientific theories must suggest some way, in principle, of being falsified by evidence • Eg. Theories of undetectable “life forces” used in some alt. medical are not scientific • Science in this view can give us certainty (the truth) about which theories are wrong

5. Non-Falsifiable “Scientfic Theories” • Popper wanted to show why certain theories that claimed to be scientific were not really scientific: • Marxist “Dialectical Materialism” • Freudian “Sub-conscious” • Dialectical Materialism predicated that working class would eventually revolt after modern production methods achieved a critical point at which scarcity was overcome • Psychoanalysis argued that our minds will always prevent us in some way from knowing our own truest and deepest “sub-conscious” motivations

6. Other Reason to Reject the Simple “Inductivist” Model of Science • Theory of evolution “predicted” that we would find fossils with history of transitional species, but it doesn’t predict (in a way that can be fully tested) the future forms life will take • Paleontology (study of ancient fossils) is not really an experimental activity, rather it involves collection and careful interpretation • Einstein and Newton didn’t really do experiments to confirm their theories • Sociologists can’t do experiments on human populations/societies

7. Criticisms of Popper’s View of Science • Most scientists don’t see themselves as working to promote tentative theories • Most scientists don’t try very hard to overturn their own or the dominant theories in their profession • Most see themselves trying to “prove” or verify their theories and descriptions • Thomas Kuhn complained that Popper was too focused on the logic of scientific thought and not the historical and sociological investigation of what scientists actually do

8. Thomas Kuhn’s “The Structure of Scientific Revolutions” • Many historical examples of revolutions in science: • From Ptolemaic, to Copernican, to Keplerian models of the solar system • From Newton’s gravity as force to Einstein’s gravity as property space • From the orbital model of the atom to the quantum “cloud” model • Each revolution claims that its scientific work “proves” its theory is “true”

9. Revolutions in Science • But if scientific methods and their examination of evidence produce such continuously contradictory claims about what is true, how are scientists really deciding to move from one theory to another? • Is it truly the case that newer theories are building on “the shoulders” of older theories creating a “pyramid of knowledge (i.e. justified true belief)?”

10. Is Science Really Cumulative? • Gravity for Newton was a “force”, but for Einstein it is an effect of the shape of space • Newton’s definition is not clarified by Einstein, it is simply shown to be false

11. Gravity is property of the shape of space, not a force • http://www.pbs.org/wgbh/nova/einstein/rela-space-w-220.html

12. Scientific Paradigm • Set of unquestioned assumptions about what the world is like • A theory, picture, or model of how the world operates that acts as a guide to the practice of “normal science” (long periods of evidence gathering within and in support of a paradigm) • Set of standard methods for scientific investigation in a specific field or research

13. Paradigm Shifts • So, how do scientists decide when to shift theories if it is not about simply recognizing the obvious truth of a new theory? • Kuhn suggests that scientists are bound by certain shared values, assumptions and methods, which they must accept if they wish to remain a part of the scientific community defined by a specific paradigm • It’s an inherently social process of consensus formation

14. Normal Science • Thomas Kuhn points out that contrary to popular view, science is not, for the most part, about making “ground breaking” discoveries, but about doing all the possible kinds of experiments suggested by a paradigm that can confirm what is predicated by that paradigm (normal science) • Minor anomalies that might threaten a paradigm are usually ignored (set aside) until another revolutionary period occurs (leading to a “paradigm Shift”)

15. Kuhn on How to Distinguish Between Science and Non-Science • Difficult to distinguish between science and non-science • What we have instead are a set of different historical pictures about how the universe works • “Science” could simply be a recent word of praise that Western societies have come to apply to currently predominant scholarship, methods and views of how the world works