Q&A: Scientific Realism
Scientific Realism
Question
Hello and greetings,
In column 426, and also in the responses to that column (as well as in the series "Learning from Experience" and in other places), you argued that there is empirical evidence that our intuition, in the context of the principle of simplicity, is correct. I accept the claim that simplicity leads us to theories that work, but my question is how one moves from the claim that theories work to the claim that they are true. In one of the responses you argued that it cannot be otherwise, since otherwise it would be a miracle that all the theories are false and yet still succeed. That is Putnam's no-miracles argument, but in the Open University book (in the philosophy of science course) they brought an objection to the argument:
Assume that the success of a theory predicts, with 90 percent probability, that it is true, and predicts only 10 percent probability that it is false (that is, success does not indicate truth with certainty). If we have 1,000 theories, and since we know there are many more false theories than true ones, we can assume that 1 percent of them are true, that is, 10, and all the rest, 990, are false (this is a common assumption, since there are very many false theories, both actual and theoretical, that can fit the findings). Out of our 10 true theories, there is a 90 percent chance that success will indicate that they are true, meaning a pretty good probability that 9 of those theories are indeed true. But out of 990 false theories, for 10 percent of them we will say that they are true, and so it turns out that we have 99 false theories that the success test tells us are true. So the ratio is 99:9 in favor of the false ones. From this it follows that if I have a successful theory, there is an 11 percent probability that it is true and an 89 percent probability that it is false. It follows from this that a successful theory turning out to be false is not a miracle at all; in fact, it is even more probable.
Do you find a flaw in this argument? If not, how would you explain the move from a theory's being successful to its being true, aside from intuition?
Answer
I presented this argument in detail in column 426 and in the article linked there. It would be good for you to read it there.
Discussion on Answer
If the theory is not correct, the chance that it will work is negligible. The theory works. Therefore it is correct. All the theories work, not just a small percentage. A few of them are replaced because of inaccuracy.
Beyond that, when I said that the chance that they would work is negligible, I also took into account the very large number of theories. My claim is that there is no chance that science would have progressed otherwise. And as is well known, it does progress.
I read the article and did not find such an argument.
The argument you make there, as I understood it, is an argument saying that one can determine statistically that our theories work (because they produce predictions that succeed, and there is no chance this would happen if the value of simplicity were just a shot in the dark). But what I did not find in the article was any discussion of why the fact that our theories work means that they are also true (that they describe existing forces and entities, and real relations and properties). For that question, the principle of simplicity does not help us, and according to the statistical argument I presented, chances are that most of our successful theories are false.
Maybe I missed something?