Ontic structural realism: what's the difference between 'structures are all there is' and 'all there is are structures'?

Question

I'm a physics student reading a philosophy essay about ontic structural realism and quantum field theory. In that paper, the author presented ontic structural realism(OSR) and radical ontic structural realism(ROSR). The former claims 'Structures are all there is', whereas the latter says 'all there is are structures.

My question is I don't think I quite understand the difference between the two. More specifically, what makes ROSR a stronger claim, compared to OSR?

Thanks for the help!

Answer 1

Okay, so if one examines the abstract, he spells out the position, however, one has to be familiar with some basic ontology to make sense of that abstract. Let's see if I can't do that for you.

Ontic structural realism refers to the novel, exciting, and widely discussed basic idea that the structure of physical reality is genuinely relational. In its radical form, the doctrine claims that there are, in fact, no objects but only structure, i.e., relations. More moderate approaches state that objects have only relational but no intrinsic properties. In its most moderate and most tenable form, ontic structural realism assumes that at the most fundamental level of physical reality there are only relational properties. This means that the most fundamental objects only possess relational but no non-reducible intrinsic properties. The present paper will argue that our currently best physics refutes even this most moderate form of ontic structural realism. More precisely, I will claim that 1) according to quantum field theory, the most fundamental objects of matter are quantum fields and not particles, and show that 2) according to the Standard Model, quantum fields have intrinsic non-relational properties.

This all boils down to a fundamental metaphysical question. What is the universe fundamentally like or made of? OSM says that at the bottom of atoms, quarks, and what have you, things we recognize as physical stuffs like matter and energy, we should sweep aside these ideas and make the claim there is something that is a structure or a relationship that characterizes everything. I don't spend much time in the philosophy of physics, but it seems to me that this article uses structuralism in a sense different than that discussed in the SEP's "Structuralism in Physics" which seems to be epistemic (knowledge-oriented) and more in line with thinking coming from the SEP's "Structuralism in the Philosophy of Mathematics" which is much more ontic (thing-oriented).

So, it looks like there are some philosophers of physics that are arguing that the fundamental stuff of the universe is relationships or structure itself, and the radical form basically claims that there are no "things", but rather every "thing" is just an aspect of the ultimately indivisible structure of the universe itself. This conversation, therefore, takes a dive into mereology (SEP), which might be considered the philosophy of relations and structure.

So, you have to ask yourself these questions.

If there are physical objects called atoms composed of sub-atomic objects, and those sub-atomic objects ultimately have properties as waves and particles, should we consider the basic stuff the mathematical relations that characterize waves and particles as even more fundamental?

If you say yes, then you are a structuralist because you are asserting that the structure of the matter and energy is what is important, not the particulars. If you then go on to say, you know, everything relates to everything, so I can't draw a line around anything, then you are being radical, if you claim that means there are no individual objects at all. Mereological nihilists do that. So, radical ontic structuralism is a form of mereological nihilism applied to a view that might be considered mathematical structuralism (since it's the math that constitutes the physical relations in discussion). This is some complicated stuff.

Let's take a physics example. The probability wave of a particle's location function doesn't end mathematically, but stretches out infinitely. If it does so, doesn't it overlap with the entire universe? If it does, doesn't it means it's merely a part of an indivisible universe?

These discussion in philosophy are part of discussions revolving around realism and instrumentalism.

Answer 2

Some cash-outs:

1. "Structure is all there is": out of the many things that we say exist, things primarily identified in terms of being structures are the only things that "actually" exist.
2. "All there is, is structure": for anything we say exists, even things not primarily identified as structures, there is "eventually" a structuralist way to describe that thing (a way for that thing to serve as the structure of something else (or of itself?)), so everything that exists, exists as a structure.

Or (1) non-structuralist discourse can be universally replaced/displaced by structuralist discourse and then (2) non-structuralist discourse can be universally translated into structuralist discourse.

I don't (yet) want to say that (2) is stronger than (1), though, so maybe this interpretation is off. Unless (2) really is stronger (or strong enough to "do the job," at least, maybe).