Quine writes right in the beginning of Word and Object: “Scientific neologism is itself just linguistic evolution gone self conscious, as science is self-conscious common sense.” That are great words. He points at a point that was made by pragmatists like Peirce. The project of science is not different in kind than our everyday investigations into everyday affairs. The methods that I use when I want to know with which train I come the fastest from location A to B and the methods that I use when I want to know what are the most basic elements of the universe are only different in degree but not in kind.
Science developed out of common sense and both influence each other. I think that is why the demarcation problem between science and non-science is so hard to solve. The people who said in the 20th century that they don’t need philosophers to tell them how science works, namely physicists now are debating over the question if a branch of modern day physics is real science or just metaphysical speculation. I’m talking of string theory.
The Philosophers’ Magazine just published an article that shows that the most important physicists of our days are taking part in philosophical debate about the scientific status of string theory. On the one site there are – how they call it – the “Popperazzi” who defend the very simplified version of Poppers falsifcationism. Popper claimed that a theory is only scientific if you can at least in general falsify it. That’s why thermodynamics is scientific and Marxism and psychoanalysis is not, at least so he thought. Marxism and psychoanalysis can acommodate every piece of evidence into their theory.
On the other site there are physicists who defend the string theory and say that falsification is not the primary feature of scientific theories. It is interesting to see that the field of the philosophy of science is revived just now by physicists. My advise is that physicists and philosophers of science should sit together on one table and inform each others about their field. There is much to learn for philosophers about modern day physics but there is also much to learn for physicists from philosophers of science since the field evolved since the days of Popper.