# What is Interesting in the Philosophy of Physics?

Philosophers of physics may have experienced this problem. You know you’re interested in a particular question about physics. You come face to face with the mountain of literature on the topic. And you immediately start digging furiously. Deeper and deeper you dig, until you’ve finally mastered a wealth of material, and at the same time completely lost track of what the hell you were doing in the first place

To avoid this problem, John Norton suggested that Elay Shech and I make a list of really successful tactics in the philosophy of physics. The idea is to characterize a few exemplary problems in the field in terms of a very broad methodology. That way, one can more easily stay focused on the really interesting problems. Here is the list the three of us came up with.

1. Correction of a standard history. Sometimes, everyone agrees that things went one way, and they all turn out to be wrong. Examples. For years, everyone thought that the Michelson–Morley experiment lead to the discovery of Special Relativity. It turns out that this experiment had little to do with it.
2. Explication of a concept in physics. A theoretical term might allow a non-standard interpretation, or might not have an obvious interpretation at all. Examples. The concept of gauge and of the simultaneity relation.
3. Traditional philosophy illuminated by physics. A particular physical theory might imply something about more traditional problems in philosophy. Examples. Claims about substantivalism, the persistence of objects, and the passage of time have all received arguments that draw on physical theories.
4. Characterization of a a theory’s foundation. Something is suggested about the most basic elements of a theory. Examples. Realism, interpretations of GR or QM, or the conventionality of geometry.
5. Analysis of ‘paradoxes.’ The word ‘paradox’ is common in physics jargon, but it almost never means a logical paradox. Analysis of what’s at the bottom of the problem is often illuminating. Examples. The black hole information paradox; the paradox of cosmic acceleration.
6. Synthesis of Philosophy and Science. One often seeks to understand how big-picture philosophical views can be combined with particular physical theories. Examples. The combination of reductionism with statistical mechanics.
7. Characterization of epistemic/metaphysical limitations. Sometimes physical theories seem to place sharp limits on what can in principle exist or be known. Examples. Indeterminism. Observationally indistinguishable spacetimes.

This list is certainly not exhaustive. But I have already found it to be surprisingly useful. Comments and additional suggestions are welcome!

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