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Friday, 12 October 2018

Bertrand Russell on Quantum-Mechanical Particles (2)

Way back in 1927 (in his book An Outline of Philosophy), and at the height of the “revolution” that was quantum mechanics, Bertrand Russell fused psychological (i.e., Humean) insight with hard science when discussing whether or not particles are things.

Russell believed that particles aren't things. He wrote the following:

The idea that there is a little hard lump there, which is the electron or proton, is an illegitimate intrusion of common-sense notions derived from touch.”

It's here that Russell offers us both a empiricist and psychological account of what's happening here. The following is the observational or experimental reality, Russell writes:

“The events that take the place of matter in the old sense are inferred from their effect on eyes, photographic plates, and other instruments.”

As for the specifics of his rejection of a thing-ontology, Russell goes on to say that “[t]here is no reason to suppose that there is a 'thing' at the place where the 'crinkle' is most crinkly”. In parallel, Russell also says that “matter has ceased to be a 'thing'”. However, doesn't the layperson believe that there is matter and that there are also things? That is, things are made up of matter; though matter (what philosophers call a mass term) itself is never a specific thing. Then again, an ontologist can just as easily say (via stipulation and ontological analysis) that a mere lump of matter can indeed be deemed to be a thing too. (Think here on the lump-of-clay-to-statue disputes in contemporary metaphysics.)

The Science of Particles

So what is the scientific reality of particles (in this case, electrons and protons)? Russell offered us a hypothesis on the matter. He said that “[f]or aught we know, the atom may consist entirely of the radiations which come out of it".

He then predicted the obvious response when he said that it's “useless to argue that radiation cannot come out of nothing”. Yet surely that response is understandable. Russell's position here is a little counterintuitive. He states that the something-from-nothing scenario is no less or no more “intelligible” than thinking that radiation “comes out of a little lump”. However, surely it can be said that the idea that radiation comes out of lumps is more (not less) intelligible than saying that it comes from nothing. No matter how inaccurate the idea is that protons and electrons are things (or "lumps of matter”), it's still more believable than stating that radiation can come out of nothing.

Bertrand Russell also expressed more of his basic science of electrons and protons and why it is that we take them to be things. Thus, in point of fact,

“the modern physicist faces cheerfully the possibility than an electron and a proton may mutually annihilate each other, and even suggests that this may be the main source of the radiant energy of the stars, because when it happens it makes an explosion”.

Thus firstly we conjecture that the electron and proton have some kind of mutual relation with one another. That alone will raise questions as to their ontological reality as separate entities (or what philosophers call “individuals”). In other words, if two things - a and b - always have a necessary and “mutual” relation to one another, then what right have we to see them as distinct entities in the first place? 

(Note that all this isn't directly connected to the notion of entanglement. It also turned out that it is electrons and positrons which "annihilate each other", not protons and electrons. Paul Dirac theoretically hinted at the positron in 1928 and Carl David Anderson discovered it in 1932 - Russell was writing in 1927!)

That later possibility is scientifically elaborated upon when Russell tells us “[w]hat can be asserted” about these matters (i.e., the electron or a proton). He writes:

“When energy radiates from a center, we can describe the laws of its radiation conveniently by imagining something in the centre, which we will call an electron or a proton according to circumstances, and for certain purposes it is convenient to regard this centre as persisting, i.e. as not a single point is spacetime but a series of such points, separated from each other by time-like intervals. All this, however, is only a convenient way of describing what happens elsewhere, namely the radiation of energy away from the centre. As to what goes on in the centre itself, if anything, physics is silent.”

Whereas earlier I said that the word "centre" was being used as a substitute for the word "thing", now Russell speaks of '"spacetime points" instead. Thus even though Russell says that “what goes on in the centre itself, if anything, physics is silent”, he still feels comfortable talking about "spacetime points".

Events & Substances

Russell also offered us a physicist's overview of events. He said that “[m]odern physics, therefore, reduces matter to a set of events which proceed outward from a centre”.

Since Russell states that the idea that radiation comes from lumps is unintelligible, then why is it any more intelligible to say that “events” (or radiation) “proceed outward from a centre”? Is a physical center more intelligible than a lump? Despite saying that, Russell backs himself up by making the Kantian point that “[i]f there is something further in the center itself, we cannot know about it”. Indeed such a thing is “irrelevant to physics”.

To put it simply: Russell believed that there are only events. We mistakenly believe, however, that there are also things. Russell went on to argue that “[w]e must think of a string of events” as a “thing”. Psychologically this is accounted for by the fact that different events are seen to be “connected together by certain causal connections”. One (Humean) conclusion to this is that we deem such events to have “enough unity to deserve a single name”.

This ostensible movement of things is also accounted for when Russell says that when “the events are not all in the same place”, we then “say the 'thing' has 'moved'”. However, such a belief is “only convenient shorthand”.

Russell scientifically and metaphysically concludes that “it can be no part of legitimate science to assert or deny the persistent entity”. To assume a persistent thing is to “go beyond the warrant of experience”.

Russell carries on his theme of Humean constant conjunction (as it were) by speaking of a light-wave. He says that these too are a “connected group of rhythmical events”. And, as before, Russell rejects the idea that a light-wave is a thing. It is, instead, a “connected group of rhythmical events”. The only thing that can be said here is that I doubt that even scientifically (or philosophically) illiterate people deem light-waves to be things in any strict/literal sense of that word. Then again, all this depends on how closely we tie the word “thing” to the word “individual” or “particular”.

Traditionally, things (or particulars/individuals) were required to have “substances” to be the things that they are. In addition, all things (or substances) were deemed to be impenetrable. As Russell puts it, “[i]mpenetrability used to be a noble property of matter”. However,

“[t]he events which are the real stuff of the world are not impenetrable, since they can overlap in space-time”.

To offer more on Russell's position on ontological substances, Russell wrote:

“It was traditionally a property of substance to be permanent, and to a considerable extent matter has retained this property in spite of its loss of substantiality. But its permanence now is only approximate, not absolute. It is thought that an electron and a proton can meet and annihilate each other; in the stars this is supposed to be happening on a large scale. And even while and electron or a proton lasts, it has a different kind of persistence from that formerly attributed to matter.”

Thus, just as it can be said that the word "centre" has become a substitute for the word "thing" in Russell's ontology; so Russell also seems to think events are (in a sense) things too. This is shown in Russell's articulation of the meaning of the philosophical theory of neutral monism.

Firstly he says that neutral monism is monism “in the sense that it regards the world as composed of only one kind of stuff, namely events”.

What about Russell's "pluralism" of entities? He then tells us that “it is pluralism in the sense that it admits the existence of a great multiplicity of events”. It's here that the notion of a thing (or an entity) is resurrected. Russell tells us that “each minimal event" is seen as "being a logically self-subsistent entity”.

Thus does that mean that we're left with a simple identity-statement? Namely:

event = "self-subsistent entity” = a thing

Intrinsic & Extrinsic Properties

Russell also asks us this question:

“What do we mean by 'piece of matter'?”

He answers his own question by telling us that “[w]e do not mean something that preserves a simple identity throughout its history”. Now that statement is partly correct and partly incorrect. It's true that any particular thing (or "piece of matter") won't be have precisely the same properties over time (this may not be true of particles, depending on how we see them). That is, object O at time t will be different in some - or in many - ways to O taken at, say, t2. (In everyday terms, there are things about Paul Murphy which are true in October 2018; though which won't be true of Paul Murphy in February 2019. The same can be said of an oak tree.)

In other words, an object or entity needn't “exist complete at every moment”, as Russell puts it. So it depends on what's meant by the word “complete”. If it means everything that belongs to object O at time t will not do so at t2, then that's correct. Though an entity doesn't need to be the sum of literally all its properties at every single point and place in time in its existence (which was Leibniz's position, at least according to Robert Stalnaker!). It's only the case that certain (essential) properties are passed on from t to t2 to tn. Of course if there aren't any essential or intrinsic properties in the first place, then this scenario can't work and we must take Russell literally.

So it doesn't follow that because an x doesn't remain identically the same in all respects over time that it doesn't remain the same in at least some respects.

In metaphysical terms, we call those unchanging aspects essential properties. However, we may not like such a reference to essential properties and want to say, instead, “important” or “enduring” properties [see Quine 1960]. Thus I will loose millions of neurons (or cells) over time; just as an oak tree will loose many of its leaves. Nonetheless, both persons and trees do have important characteristics - functional, formal and physical - which last over time. Indeed if that weren't the case, then indeed we wouldn't have any right to keep on referring to a particular thing (or even person) with the same name over time. It can be said here that Russell does believe that we have no (philosophical) right to use the same name over time because he rejects essential (or intrinsic) properties. Either that or he didn't deem the enduring or important properties of an x to also be essential or intrinsic properties.

The upshot of Russell's position (if only at this time) is that there are no intrinsic or essential properties and, consequently, there aren't really any things or objects. That is, all x's properties are both contingent or extrinsic. (Semantically, surely if there are no essential/intrinsic properties, then there are no contingent/extrinsic properties either.)

Russell's (partly Kantian) bottom line is that we have no access - either observationally or otherwise - to the intrinsic characteristics of such things. Instead “[w]hat we know about them” is simply “their structure and their mathematical laws”. That is, all we've got is structure and maths.

Thus it's structure and maths “all the way down”.


See: 'James Ladyman and Don Ross on Quantum-Mechanical Particles (3)'

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