Will science ever replace philosophy?

What is science ?: Philosophy is supposed to bail out physics

Workshop participant Carlo Rovelli, a theoretical physicist from France, is of the opinion that string theory is worth the theorists' attention, even if it cannot currently be verified. But the most important targets of Ellis and Silk were observations made by the philosopher Richard Dawid of the LMU Munich in his book "String Theory and the Scientific Method". Dawid wrote that the string theorists had begun to follow the principles of Bayesian statistics, in which the probability that a prediction is correct is assessed based on previous knowledge and this assessment is then revised based on newly acquired knowledge. However, Dawid notes, they have recently been using purely theoretical factors - for example, the internal consistency of a theory or the fact that there is simply no credible alternative - to improve their estimates instead of relying on measured data for such revisions.

During the workshop, Gross argued with Rovelli, who had been working on just such an alternative for years, namely loop quantum gravity, according to whose proposal the lack of alternatives to string theory increases its probability of being correct. Rovelli flatly rejects the assumption that there are no alternatives. Ellis, in turn, rejects the idea that theoretical considerations can improve such probabilities at all. "My answer to Bayesianism is that new evidence must be experimental evidence," he says.

Other questions about the use of Bayesian statistics to support string theory also came up. Sabine Hossenfelder, a physicist at the Nordic Institute for Theoretical Physics, Sweden, said the popularity of string theory may have contributed to the impression that it was the only alternative in the field. Presumably, however, it was more sociological reasons that caused the rise of string theory: For example, young academics might prefer to turn in this direction because the career prospects there are better than in more obscure areas.

The science historian Helge Kragh from Aarhus University in Denmark, meanwhile, used the historical perspective. "There have been suggestions that we need new scientific methods before, but attempts to replace empirical testing with other criteria have always failed," he says. At least the problem is limited to just a few areas of physics, he added. "String theory and multiverse cosmology are only a small part of what you do in physics."