Structuralism in the Philosophy of Science

Structural Realism is an attitude towards realisms of all flavours, which puts structures front and center. A structure is usually an object which encodes relational data about some other objects. Note that structures themselves do not necessarily presuppose anything ontological about these "other" objects; structures are generically schematic.

If you read introductory material on structuralism as an approach to scientific realism, you will encounter different ideas which are often sloppily interchanged:

1. Mild Scientific Structuralism
   • Science reveals to us some of the structural features of the natural world
2. Ordinary Scientific Structuralism
   • Science reveals to us the structural features of the natural world
3. Radical Scientific Structuralism
   • Science reveals to us the structural features of the world

Note that all of these positions have epistemic and ontic flavours.

(3) is most clearly out of place, as it brings the issue of naturalism into a debate where it does not belong. And yet the conflation of (2) and (3) is present in the Wikipedia¹, SEP², and IEP³ articles on the subject (as well as many casual online conversations by those who should know better). That science tells us about the natural world is almost a tautology, but that the natural word is identical to the world itself is a very different claim which has nothing to do with structuralism (and maybe not even with realism).

Whether or not distinguishing (1) and (2) is meaningful will depend on how one cashes out the notion of structure, and perhaps also the notion of science itself, but I believe it is a distinction which should at least be acknowledged. In particular, some characterizations of structures say that they are mathematical in nature, and so long as science can talk about mathematical objects (which at this point it seems it not only can but must) it can talk about structures. Thus the idea of a structure of the natural world which is immune to scientific analysis would be nonsensical. On the other hand, it might be the case that not all structures are mathematical, but also that science can talk about more than just mathematical structures. With this view one could claim that science can talk about all natural structures, but this would have to be argued for.

A serious example of (1) is the organic philosophy of Alfred North Whitehead.⁴ Whitehead was both a scientific realist and a naturalist. I would argue he was also a structuralist (or a proto-structuralist) due to his belief in the deeply relational nature of the world. However, he did not believe that scientific theories were the ultimate or complete theories of reality, as it was the job of metaphysics to provide those. But in his own metaphysical scheme, all phenomena are structural (relational) in nature, and so since science is talking about those phenomena, it tells us exclusively structural facts about the world. But importantly, those scientific facts do not exhaust the world.⁵

I think that talking about structuralism in science as though it were necessarily a kind of materialism is both misleading and hinders its possible applications to and integrations with other schools of thought.