The sky is blue. But can we claim that it will be blue tomorrow?

Person 1: ‘Oi, ye proclaimers of scientific truth, how is it that the scientific method finds objective truths?’

Person 2: ‘Through the scientific method, of course. Scientists make hypotheses (e.g. “Aspirin reduces headaches”), acquire data, then make conclusions. You’d be absurd to deny their proofs. Don’t show such folly by taking your philosophy to the extreme. Scientists are principled, rational, and logical. Take a leaf out of their book.’

Person 1: ‘You’re speaking with a matter of fact—vintage behaviour for a scientist, I should add—and I am one!—but can you follow it up? You see, you’re placing faith in scientific realism: in the notion that science finds objective truths to contribute to real-world knowledge. But how? It is totally plausible that scientific theories are built on the rejection of hypotheses (e.g. through null hypotheses and p-values), not by finding objective truths. May I suggest some Karl Popper—or, perhaps, some David Hume. Oh, yes, Hume. Consider this: Will the sky be blue tomorrow? While I believe that it will, I accept that the scientific method can’t show me why. Although we have deduced the phenomenon of Rayleigh scattering, this deduction is based on prior data and says nothing of tomorrow’s facts. There is no proof today that can serve as proof tomorrow. As absurd as this all seems to our personal intuitions, given our daily experiences of the sky, with one simple example we have reached the boundaries of the scientific method.’

Person 2: ‘ . . . ‘