33| Taking Chance Seriously — Alastair Wilson on Quantum Modal Realism

Things happen. Or they don’t. How then should we make sense of claims that something might happen?

If all these claims do is express doubt, then the puzzle can be easily resolved. But if the claims capture some objective feature of the world, what is it?

Our guest is Alastair Wilson, a professor of philosophy at the University of Leeds. He takes chance seriously, in particular, he is a realist about our modal claims (claims like “either candidate could win” or “if Szilard hadn’t got Spanish flu, the atom bomb would not have been invented”) may be true or false, not just opinions or expressions of ignorance.

Alastair does this by connecting our modal talk to Everettian quantum mechanics. He argues that modal claims are assertions about the many worlds within the universal wavefunction. If in all worlds where Szilard did not succumb to Spanish flu, the atom bomb was never invented, then this claim would be true.

It is a bold and fascinating way of bringing physics and metaphysics together. What can happen, what is possible, what could have been? These become questions for natural science.

• Alastair's website
• Nature of Contingency: Quantum Physics as Modal Realism