The Demarcation Problem: What theories should be ranked scientific

1. The Demarcation Problem: What theories should be ranked scientific? The inability of a theory to be shown false is a weakness, not a strength, since if nothing can show a theory to be false, no observation could count as confirmation of the theory either. Popper argues that falsifiability, the ability of a theory to be shown false by observation, is the criterion of scientificity. •Confirmations do count in favor of a theory if they are a result of risky predictions

2. Unscientific Theories Bad theories make one of two slippery maneuvers to avoid falsification. 1. Either they are so vaguely stated as to always allow interpretations that fit the predictions. 2. Or they offer a mythic story that all evidence is to be interpreted in light of. Such theories might be proto-scientific.

3. Popper’s Argument against Induction Popper argues that the method of science is not inductive but deductive. 1. Inductive method: gathering observations and making generalizations from them.

4. Induction, continued 2. There is no such thing as an untheoretical observation; science cannot proceed from pure observation to theory. 3. We cannot prove our theories; at best we can disprove them. 4. There is no clear criterion for when we have a “valid induction”.

5. Induction, continued 5. The most rational method of pursuing knowledge is the method of conjectures and refutations, that is, trying out hypotheses or theories by subjecting them to crucial tests. 6. This is not induction, but deduction.

6. Fallacy of Induction Induction involves a fallacious inference: If p then q q Therefore p. This is called the fallacy of affirming the consequent.

7. Falsification Suppose that we have a theory that says something like: All F are G. One single case of an F that is not a G disconfirms the theory. Likewise, one case of a prediction not being born out shows a theory false (or so says Popper).

8. Connection between Demarcation and Induction Previous philosophers tried to characterize good induction in order to say what counts as science; Popper rejects induction, claims that instead of induction what we actually do is deduction, and that this use of deduction to attempt to falsify our theories is the demarcation criterion between science and non-science.

9. Criticisms of Popper 1. It seems odd to claim that lots of confirming instances do not give us good reason to believe a theory.

10. Criticisms, continued 2. The deductive proof provided by theories is not as air tight as Popper maintains. The logical situation of an experiment is actually this: If p (and auxiliary assumptions r,s,t...) then q Not q. Therefore, not p (or not r or not s or not t...)

11. Criticisms, continued 3. Popper’s reconstruction of scientific practice is not accurate. It is difficult to believe that scientists try always to disprove their hypotheses.