Scientific Realism Made Effective

Abstract

I argue that a common philosophical approach to the interpretation of physical theories -particularly quantum field theories -has led philosophers astray. It has driven many to declare the quantum field theories employed by practicing physicists, so-called "effective field theories," to be unfit for philosophical interpretation. In particular, such theories have been deemed unable to support a realist interpretation. I argue that these claims are mistaken: attending to the manner in which these theories are employed in physical practice, I show that interpreting effective field theories yields a robust foundation for a more refined approach to scientific realism in the context of quantum field theory. The paper concludes by briefly sketching some general morals for interpretive practice in the philosophy of physics.

Reductive Explanation and the Construction of Quantum Theories

“…3 Similar themes are familiar from elsewhere in the literature-e.g., Wilson ([2006], [2013]). See also, e.g., Williams ([2018]) for other reasons to reject the standard account.…”

Philosophical foundations of effective field theories

“…The most popular response to this problem is a position called 'selective realism': even though our best theories do not get everything right, they still contain parts that are likely to remain (approximately) true [30,36,50]. Williams [48] and J. Fraser [19] have recently defended this position in the context of QFT: they argue that Wilsonian RG methods provide 'local' (i.e., restricted to QFT) tools to distinguish essential parts in current EFTs that are likely to withstand future theory change and give (approximately) true descriptions of the world. In particular, RG methods give selective realists some confidence in the claim that the low-energy content of the presently most successful EFTs is largely independent of the high-energy content of future theories and is therefore likely to remain unaffected by the discovery of new high-energy physics.…”

“…Hence, besides selecting relevant theoretical parts, the selective realist also needs to say what these parts represent in the world. Williams makes a first step in this direction by criticizing the standard realist interpretative strategy: it "has led philosophers astray" in the context of QFT [48]. In particular, some philosophers highly concerned with the infamous mathematical issues plaguing realistic QFTs have been drawn to believe that mathematically rigorous yet highly unrealistic QFT models in lower dimensions give us more reliable ontological information about the world than the heuristic yet empirically adequate QFT models in high-energy physics.…”

The dynamical approach to spin-2 gravity

“…Hence, we should be honest about what physics can and does provide us with: I think that in regarding the standard model and general relativity as effective field theories we're simply balancing our checkbook and realizing that we perhaps didn't know as much as we thought we did, but this is the way the world is and now we're going to go on the next step and try to find an ultraviolet fixed point, or (much more likely) find entirely new physics. (Weinberg, 1999, 250) But-pace Redhead (1999)-this does not mean that effective field theories thereby block the search for fundamental laws of nature or scientific realism (see Williams (2017)). It may seem no surprise, though, that probably the most important reductive aspect of the spin-2 proposal concerns the reduction of a theoretical concept-the SEP-to another (arguably more fundamental) theoretical concept-Lorentz invariance.…”