James Ladyman: What is Structural Realism?

A live, text-driven seminar on major works in philosophy (mostly analytic). We read the paper together, slowly—stopping to clarify terms, reconstruct arguments, and stress-test claims. You can find the next week's reading here

WARNING

Browse the current and upcoming papers along with past Readings and meetings. Expect highly technical material, dense terminology, and high abstraction. It is full of philosophical jargon and complex technical terms. Your expectation should be to treat it as a graduate seminar in philosophy. We don't assume you have a degree in philosophy, but we do assume philosophical maturity and/or a crazy level of passion for deductive reasoning. If you are into that sort of thing, be my guest. We will start reviewing the paper, and start reading from page 1 of the PDF.

DETAILS

This paper tackles one of the oldest and most annoying problems in philosophy of science: how science can be wildly successful while being historically wrong about what the world is made of. Electrons replaced ether, fields replaced particles, spacetime replaced forces—and yet physics keeps nailing predictions. Coincidence? Probably not.
Ladyman’s answer is structural realism: the idea that what science gets right is not objects but the structure of relations captured by successful theories. When theories change, the ontology may get junked—but the mathematical and relational structure often survives. That continuity, Ladyman argues, is what realism should commit to.
The paper does three things:

1. Diagnoses the failure of naive scientific realism
   Traditional realism says mature theories are approximately true descriptions of the world’s entities. History says otherwise. Ladyman takes the “pessimistic meta-induction” seriously and refuses to wave it away.
2. Clarifies epistemic vs ontic structural realism
   Epistemic SR says we can only know structure. Ontic SR goes further: structure is all there is. Objects are secondary, derivative, or outright dispensable. This is where things get metaphysically spicy.
3. Connects structural realism to modern physics
   Quantum mechanics, quantum field theory, and relativity don’t play nicely with classical objects anyway. Group structure, symmetries, invariants, and relations do the real explanatory work. If physics already ditched billiard-ball ontology, philosophy should stop clinging to it like a security blanket.

This is not a “let’s split the difference” compromise between realism and anti-realism. Ladyman is arguing that realism survives only if we radically revise what we mean by reality. If you think science tells us what exists, this paper forces you to ask: exists as what—objects, or structure?
Fair warning: this is a gateway drug to ontic structural realism, elimination of objects, and the idea that relations may be metaphysically fundamental. If you like your ontology chunky and intuitive, expect discomfort. If you like symmetry groups more than substances, you’ll feel right at home.