The Demarcation Problem and Falsifiability
Lesson Plan
One of the practical consequences of the Scientific Revolution was a suggestion that one should only believe things that are both true and justified. Eventually, there was even the proposal by mathematician William Clifford that it is morally wrong to believe things without good justification. While early thinkers suggested we need to justify all of our own beliefs, science and the world are far, far too complicated for each of us to confirm all of our beliefs. We need to have a system to help us decide.
The challenge this raises involves what to believe. Is Chemistry well founded? Astrology? How can we tell the difference between what we might call science and pseudoscience? The stakes are quite high here…think about medicine. How can you tell which pills to take to cure your illnesses?
One set of famous and prominent suggestions comes from Karl Popper who writes this:
1. It is easy to obtain confirmations, or verifications, for nearly every theory–if we look for confirmations.
2. Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory–an event which would have refuted the theory.
3. Every ‘good’ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
4. A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.
5. Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
6. Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of ‘corroborating evidence’.)
7. Some genuinely testable theories, when found to be false, are still upheld by their admirers–for example by introducing ad hoc some auxiliary assumption, or by re-interpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a ‘conventionalist twist’ or a ‘conventionalist stratagem’.)
Discussion Questions
- Why is the Demarcation Problem important?
- What does Karl Popper mean by falsifiability?
- What is the difference between saying “we should only believe things which can be falsified” and saying “we should only believe things which are false?”
- Arthur Eddington’s 1919 confirmation of Albert Einstein’s theory of evolution was held by Popper to be a perfect example of a risky claim that made a falsifiable prediction (that is it laid out the terms under which it would be shown to be false). What does this mean?
- Popper writes “The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which "verified" the theories in question; and this point was constantly emphasized by their adherents,” another way of saying that confirming evidence is “cheap” or “easy”. What does he mean by this?
- Explain the difference between these two sentences on Popper’s grounds (i.e. the difference between bad science and pseudoscience): “Lightning doesn't strike the same place twice” and “Human psychology is affected by the location of Mars.”
- Is falsifiability falsifiable?
- Is the Demarcation Problem important? Formulate arguments for and against this position.
- Ludwig Wittgenstein in his work, Philosophical Investigations regularly referred to the concept of language games. He argues that concepts do not need to be clearly defined to be meaningful. Are there some areas between science and pseudoscience that can never be fully decided on?
- Darwinian evolutionary theory is the bedrock of modern biology. Is it falsifiable? If not, how is this point significant?
- Are there times we should hold onto some beliefs that fail empirical scientific tests (How can we know whether the hypothesis is false or if the instruments failed, or something else accounts for this failure)?
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