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Monday, 22 October 2018

Ladyman and Ross on Quantum-Mechanical Particles: Things, Structure and Relations (4)



Things and Structures

The most important aspect of ontic structural realist position can be expressed in the following way:

Relata (i.e., things/objects/particles/etc.) can be eliminated. Then all we will have left is relations.

James Ladyman and Don Ross ground their own philosophy by expressing Bertrand Russell's position in the following manner:

... many philosophers have followed Russell in arguing that it is incoherent to suppose there could be individuals which don’t possess any intrinsic properties, but whose individuality is conferred by their relations to other individuals.”

Indeed that passage can be rewritten to make it more germane to Ladyman and Ross's own ontic structural realism. Thus:

It is incoherent to suppose there could be individuals (e.g., particles, etc.) which don’t possess any intrinsic properties, but whose individuality is conferred by their relations to other individuals, structures, fields, states, etc.

Thus we can ask the following question:

Does a thing/object gain its identity from its place in a structure or does it have its place in a structure because of its (prior) identity?

Indeed Ladyman and Ross state that Paul Benacerraf believed that

an object with only a structural character could be identified with any object in the appropriate place in any exemplary structure and could not therefore be an individual”.

In other words, Benacerraf seems to have taken the position cited earlier. Namely, an object/individual has its place in a structure because of its (prior) identity. That is, an object/individual doesn't gain its (entire) identity from its place in a structure.

To elaborate on Benacerraf's position. It can be said that if structure is everything (or, at the least, if an thing/object gains its identity from its place in a structure), then any thing/object can take a place in that structure. Indeed any thing/object can take specific place x in a given structure if the individuality or identity of an object is passed onto it (as it were) by the structure it is a part of.

The problem with this (or perhaps any) form of structuralism, however, is summed up by Ladyman and Ross who state that “individuals are nothing over and above the nexus of relations in which they stand”. However, they do preface that by saying that this position – only? - applies to “individuals in the context of quantum mechanics”.

Ladyman and Ross continue by saying that “the identity or difference of places in a structure is not to be accounted for by anything other than the structure itself”. Not only that: the mathematical structuralism just discussed “provides evidence for this view”.

Despite all that, Ladyman and Ross often state that they don't actually deny the existence of entities or individuals per se. Yet it's hard to make sense of their claim that “there are objects in our metaphysics” and then go on to state that

but they have been purged of their intrinsic natures, identity, and individuality, and they are not metaphysically fundamental”.

In other words, if you take away “intrinsic natures, identity, and individuality”, then what's left of things/objects after all that has been taken away? Only structure and/or relations? But what does that mean?

In any case, Ladyman and Ross see individuals as “abstractions from modal structure”. By “modal structure” they mean

the relationships among phenomena events, and processes) that pertain to necessity, possibility, potentiality, and probability”.

It can easily be said that structures involve individuals and relations involve relata. At a prima facie level we can also ask:

In what way do “abstractions” involve themselves in modal realities?

Well, mathematics itself involves necessity, possibility and probability. And if structures are inherently mathematical, then structures have modal properties. All that may be true. Though what about modality as applied to the concrete world of objects, events, conditions, states, etc? What about metaphysical modality as understood by philosophers like Saul Kripke, David Lewis, D.M. Armstrong and so on?

Ladyman and Ross also quote the American philosopher of science John Stachel when he says that entities “'inherit [individuality] from the structure of relations in which they are enmeshed'”. However, saying that is a long way from saying that individuals don't exist. Even the very use of the word “inherit” surely means that it must be things which are doing the inheriting.

Now is it that Ladyman and Ross reject this position and simply deny ontological status to things/objects - full stop? Or is their position that entities inherit their individuality from the “structure of relations in which they are enmeshed” as far as they need to go? Thus it's not that Ladyman and Ross are eliminitivists about things/objects. It's simply that they have a radical philosophical take on things/objects. A take which claims that entities gain their individuality from structure. That is, before things/objects are “enmeshed” in structures, they have no intrinsic natures.

Can we go so far as to say that before things/objects are enmeshed in structures, they don't exist? Thus it's not just the nature of entities we're talking about: it's also their existence. Do entities spring into being only when they're enmeshed in structures?

This position would go against the claim (for example, of David Lewis) that objects have intrinsic natures regardless of the rest of the world.

So now we still have the following positions:

i) Things gain their natures from the structures they belong to.

ii) Things come into existence in structures.

How is i) different from saying that entities are structures? In other words, the temporal and grammatical construction of i) may seem to imply that we have an entity at time t1 - and at t2 it gains its nature from the structure it's embedded in. However, if ii) is correct, than that entity comes into existence in the structure. It doesn't only gain its nature from a structure – it comes into existence in the structure in which it's embedded.

Such abstract metaphysics is made concrete when Ladyman and Ross take the example of fermions. They cite the position that

that fermions are not self-subsistent because they are the individuals that they are only given the relations that obtain among them”.

What's more, “[t]here is nothing to ground their individuality other than the relations into which they enter”. And, according to Ladyman and Ross, even Albert Einstein once claimed that particles don't have their own “being thus”.

Substantivalism

As just hinted at, one problem which can be raised about things/objects (as well as about Ladyman and Ross's position) can be expressed by stating two positions:

i) Things/objects have their intrinsic natures independently of the rest of the world.

ii) Things/objects can exist independently of the rest of the world.

This problem specifically arises in the context of “points of spacetime” rather than objects. (Although it may be said that they amount to the same thing.) In this case, Ladyman and Ross use the word “exist” (as in ii) above). This is also a product of two different positions: substantivalism and relationalism. Thus:

i) According to substantivalism, the “points of the spacetime manifold exist independently of the material contents of the universe”.

ii) According to relationalism, “spatio-temporal facts are about the relations between various elements of the material contents of spacetime”.

The idea that “points of the spacetime manifold exist independently of the material contents of the universe” is similar to David Lewis's take (1982) on the intrinsic properties of things. Lewis wrote:

A thing has its intrinsic properties in virtue of the way that thing itself, and nothing else, is.”

Lewis's position (if not the substantivalist position) can be taken to its most extreme in the following statement:

Object a would still have intrinsic property P if, after the world around it disappeared, a would still have P.

In Ladyman and Ross's rendition of substantivalism, it's said that an object or point in spacetime could “exist” regardless of everything else. Could there ever be “the way that a thing itself is” regardless of everything else? That is, can object x be the way that it is regardless of its relations to other properties/objects/events/states/etc. and its place in spacetime?

Things and Relations

Ladyman and Ross provide a useful set of four positions which focus on the nature of relations and things. Thus:

i) There are only relations and no relata.
ii) There are relations in which things are primary, and their relations are secondary.
iii) There are relations in which relations are primary, while things are secondary.
iv) There are things such that any relation between them is only apparent.

At first glance one would take ontic structural realism to endorse (i) or (iii). However, if things are themselves structures (according to Ladyman and Ross), then we must settle for (i) above: “There are only relations and no relata.”

Looking at (i) to (iv) again, couldn't it be said that (ii) and (iii) amount to the same thing? In other words, how can we distinguish

(ii) There are relations in which the things are primary, and their relations are secondary.

from

(iii) There are relations in which relations are primary, while things are secondary.

Isn't this a difference which doesn't make a difference? One can still ask - in the metaphysical pictures of (ii) and (iii) - the following question:

Can things exist without relations and can relations exist without things?

That's a question of existence. Now what about natures?

One can now ask:

Can things have their natures without relations and can relations have their natures without things?

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To follow: 'On Quantum-Mechanical Particles: Conclusions (5)'



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