The Demarcation Problem Science and pseudoscience Case one

“The Demarcation Problem” (Science and pseudo-science) Case one: Geocentrism (an earth-centered universe) vs. Heliocentrism (a sun centered universe).

“The Demarcation Problem” Case one: Geocentrism (an earth-centered universe) vs. Heliocentrism (a sun centered universe). Was geocentrism a scientific hypothesis? How much of it was based on theology or appeals to ancient authorities (such as Aristotle), rather than on empirical evidence and/or scientific reasoning? Was heliocentrism a scientific hypothesis? How could it be if it so obviously clashed with our experience? Where is the wind? Why don’t we feel the earth’s motion? How does a telescope work? How do we know what Galileo claimed to see (e. g. , that Jupiter has moons) weren’t just artifacts produced by his telescope?

Popper: “Falsifiability is the criterion” Ø Why reject verifiability? Ø By then (for reasons we will study shortly), scientists and philosophers recognized that no empirical theory could ever be proven. Ø This seemed to take any degree of certainty off the table Ø Moreover, according to Popper, “verifications” or confirmations of a theory were, in many cases, all too easy to come by.

Popper: “Falsifiability is the criterion” Ø By then (for reasons we will study shortly), scientists and philosophers recognized that no empirical theory could ever be proven. Ø But Popper has logic on his side; for while no empirical theory can be proven, any (genuinely) empirical theory can be disproven and, at least in principle, by just one failed experiment or prediction.

The logic of confirmation vs. the logic of falsification If H, then I 2. I ---------H Logic of confirmation: Affirming the consequent Deductively invalid 1. If H, then I 2. Not I ---------Not H Logic of falsification Modus Tollens Deductively valid. 1.

Popper: “Falsifiability is the criterion” Ø In 1919, Popper compares 4 then popular and much discussed theories: Relativity, Marxism, Freudianism, and Adlerian Psychology Ø Although the last three might contain important truths or insights, and although they are said to enjoy extensive confirmations (supporting observations and “experiments”), they turn out not to be scientific, according the Popper. Ø Although it was unclear at the time whether Einstein’s theory was true, it turns out to be scientific on Popper’s view.

Eddington’s experiment Ø Einstein’s theories predicted that light, like material objects, is subject to the gravitational “pull” of large objects Ø Hypothesis: light traveling from a star that is located “behind” the sun from the perspective of the Earth should bend as it passes the sun Ø A bold hypothesis and one that would take years to carry out. Scientists had to wait for a solar eclipse so that a star’s light would be visible

Eddington’s experiment Ø A reconstruction of what Eddington’s photographs demonstrated:

Eddington’s experiment Ø A bold hypothesis and one that would take years to carry out. Scientists had to wait for a solar eclipse so that a star’s light would be visible Ø But it was not its confirmation that struck Popper, but its falsifiability and boldness: even before Eddington’s experiment confirmed it, scientists knew what would, in principle, falsify the hypothesis: namely, not observing the bending of the light traveling from the star toward Earth.

Falsifiability Ø The criterion used to make these judgments and to be generalized: Ø Every genuinely scientific theory is a prohibition. It forbids certain things to happen. Ø A theory that is not falsifiable (refutable) by any conceivable event is not scientific. Ø Confirmations should only count as supporting a theory if, like that of Relativity, they involve risky and bold predictions.

Falsifiability Ø Ø Ø Using the criterion to judge Marxism, Freudianism, and Adlerian Psychology as examples of pseudo-science The problems with Freudian and Adlerian psycyhology: Each is compatible with every possible state of affairs. Each contains within it the means to explain conflicting results (e. g. , whether an adult jumps into water to save a drowning child or does not jump in – explanation “his or her feelings of inadequacy”) The “unconscious” of Freudian theory undercuts any individual’s claim not to experience what Freud predicts every male, or every female, experiences.

Falsifiability Ø Marxism is rendered pseudo-scientific not because the original theory was not falsifiable. Ø Marx and Engel’s claims about upcoming proletariat revolutions in capitalist societies were falsifiable, and in most cases, falsified. Ø But advocates of Marxism, in efforts to save theory from the falsifications, introduce Ad hoc hypotheses to save it. Ø Ad hoc: From the Latin “for this purpose” (in this case, saving theory…)

Falsifiability Ø Ad hoc hypotheses and Marxism Ø According to Marxism, each society has an “ideology” – a guiding set of ideas – that informs its political and economic theories and institutions Ø Ideologies function to make the present political and economic status quo look natural Ø So, workers (members of the proletariat) don’t recognize that capitalism exploits them and have to be taught to see through the ideology that their economic system is a “meritocracy” with unlimited possibilities to succeed.

Falsifiability Ø When the many revolutions Marx and Engels predicted did not occur, later advocates of theory pointed to the capitalist ideology as the culprit: workers couldn’t see through it and recognize the truth. Hence, few revolutions. Ø Note that this is a different kind of case from Freudian and Adlerian psychology: it’s not theory that is unfalsifiable, it’s the attitude of its advocates and their willingness to propose Ad hoc hypotheses to save it from falsification

Things we will later consider… The difference between a theory actually being unfalsifiable, by its nature or structure, and a theory’s advocates resorting to ad hoc hypotheses to save it. Ø Isn’t it possible that a genuinely scientific theory will be confirmed repeatedly and no counter-examples encountered? Ø The “in principle” caveat is important. “There is a little red school house on the dark side of Jupiter” is silly but falsifiable in principle. Ø How easy or straightforward is it to identify added hypotheses that ARE ad hoc, but added hypotheses that are NOT ad hoc (i. e. , are defensible) Ø

The Elegant Universe: preview Ø The two pillars of contemporary physics – Relativity and Quantum mechanics – are (it appears) incompatible. Ø Relativity theory concerns very large objects (galaxies, starts, and the like) Ø Quantum mechanics concerns very small objects (atoms and subatomic particles) Ø They yield different laws. Ø Unification – “a theory of everything” is for many physicists the Holy Grail.

The Elegant Universe: preview Ø String Theory is seen by some physicists as precisely theory that will unite Relativity and Quantum mechanics – it is (it will turn out to be) theory of everything. Ø It posits that everything, including Lederman’s quarks and leptons, is made of tiny, vibrating strands of energy (they’re called strings) Ø It has led to some strange predictions: parallel universes and 11 (yes, 11!) dimensions, among other things.

The Elegant Universe: preview Ø Note how string theory, like particle physics, quantum theory, the Greeks of Miletus, and Democritus, assumes there is one stuff out of which everything is made. Ø Strings are, by their nature, unobservable (and, indeed, there are no technologies able to indirectly observe their effects – although some hope LHC will help here) Ø Note the primary reasons physicists who are not String Theorists reject its status as “scientific”!

The Elegant Universe: preview Ø Some of the players: Ø Brian Greene, narrator and author of the book of the same title. Professor of physics at Columbia University. An advocate of String Theory… Ø Sheldon Glashow, Professor of Physics, Harvard, Noble Prize in Physics, author of the “Credo” we read earlier. Ø Steven Weinberg, Professor of Physics, University of Texas, Austin. Shared the Noble Prize with Glashow for their construction of “The Standard Model” in physics.