Philosophy of the Sciences, Lecture 3,

13/09/03The Demarcation Problem

and Falsificationism

Science is an invention, a relatively recent invention.

There was a time in our history when there was nothing to which we’d happily apply our word ‘science’.

Not until the 17th century did what we would recognize as modern physics emerge (via Newton and his discoveries) as a separate discipline.

What we think of as biology didn’t exist until 1859 (when it emerged with the publication of Darwin’s Origin of the Species).

Psychology as we know it had to wait until the beginning of the 20th century, and computer science is an infant—only a little more than 50 years old!

Physics and biology are descendants of the philosophical sub-discipline known as metaphysics—roughly, the study of what there is: what fundamental kinds and properties there are and how they relate.

And psychology descends from philosophical reflection on the nature of the mind and its properties, i.e. the philosophy of mind. Computer science, for its part, stems from philosophy’s millennium long interest in logic.

Interestingly, all of these sciences grew from philosophical roots. (From the concerns of the ancient Greek philosophers and primarily from the concerns of Aristotle).

What makes a theory scientific?

The question is:

•intrinsically interesting

•of practical importance

-Who gets the money?

-Who wins the argument?

•crucial for understanding the value of science

-Science is an invention, claimed by many to be humanity’s best.

A better formulation:

What distinguishes science from non-science? (the demarcation problem)

Initial proposals:

(1) Science offers explanations.

(2) Science is objective.

(3) Science is descriptive.

(4) Science makes predictions.

(5) Science proceeds from observation.

The trouble with the initial proposals:

They don’t do any distinguishing.

Popper

The wrong answer to the demarcation problem:

Science is inductive; it proceeds by observation and experiment.

Why the wrong answer?

Non-scientific theories can be based on observation and experiment.

“…astrology with its stupendous mass of empirical evidence based on observation—on horoscopes and biographies.”

Popper’s 4 candidate theories:

(1) Einstein’s theory of relativity.

(2) Marx’s theory of history

(3) Freud’s psychoanalysis

(4) Adler’s individual psychology

Popper’s intuition: (1) is scientific, (2)-(4) not.

Truth not the issue. At the time, Popper didn’t believe that Einstein’s theory was true.

Exactness also not the issue.

The appeal of (2)-(4): Their apparent explanatory power.

Exposure brought about an “intellectual conversion” and confirming instances of the theory were seen everywhere.

Indeed, nothing seemed to count as disconfirmation, as evidence against the theory.

Every observation could be interpreted in light of the theory.

The Freud vs. Adler example. (p. 40)

The difference with respect to (1)— Einstein’s theory: The theory makes risky predictions, predictions which, if false, sink the theory.

E’s theory has the result that light, like material bodies, is attracted by heavy bodies such as the sun. This led to the prediction that the light from certain stars—those which appear in the night sky as close to the sun—would appear, if observed in daylight, as slightly shifted away from their normal position, slightly further away from the sun.

This prediction can’t be tested in ordinary circumstances because of the sun’s brightness.

But during an eclipse one can take a photograph of a star’s apparent position in the daytime sky.

And then photos of the star taken in the day and in the night can be compared and its apparent distance from the sun can be measured.

This is just what Eddington did.

And the prediction of Einstein’s theory was shown to be correct.

The significance of this, acc. to Popper: Einstein’s theory, unlike (3)-(4), is incompatible with certain possible results of observation.

In other words, E’s theory is refutable or falsifiable (the term that has stuck). It is possibly false. If our observations had been different, it would have been shown to be false (though they weren’t and it wasn’t).

This, then, is Popper’s solution to the demarcation problem: A theory is scientific just in case it is falsifiable.

A theory is scientific just in case it is falsifiable.

Remember: Truth is not the issue for Popper. Accordingly, his solution to the demarcation problem doesn’t make being true a criterion for being science.

Theories that are true may be falsifiable.

But, equally, theories that are false may be falsifiable as well.

Some consequences and corollaries of Popper’s solution to the demarcation problem:

•Theories not falsifiable by any conceivable event are not scientific. (Thus, the naïve view that science strives for irrefutability gets things exactly the wrong way around.)

•Every good scientific theory is a prohibition--it denies that certain things may happen.

•A test of a theory is an attempt to falsify it.

•“Confirming evidence” is too easy to come by and should only count towards the acceptability of a theory if it is the result of an attempt at falsification.

•Some genuinely falsifiable theories, when falsified, are maintained by their admirers either by re-casting the theory or adding auxilliary assumptions. Such a procedure is always possible, but it rescues the theory only by destroying or reducing the theory’s claim to scientific status. (Popper calls such rescue operations conventionalist twists.)

Who passes the falsification test?

(1)—Einstein’s theory of relativity—passes. It makes risky predictions (re: the apparent positions of stars, e.g.)

Astrology fails. Vagueness of its predictions makes it unfalsifiable.

(2)—the Marxist theory of history—fails. It once passed, but it was given various conventionalist twists.

(3) and (4)—the psychoanalytic theories—fail. No conceivable bit of human behavior could refute them.

Non-science but not unimportant. Analogy with primitive myths. These myths often shape later science (the ancient Greek examples).