This is the third part in a series where I attempt to understand Arthur Eddington’s ‘Philosophy of the Physical Sciences‘, written in 1938. My interest in this book is twofold. Firstly, I’m curious to learn why a physicist as accomplished as Eddington made the seemingly ridiculous claims that he knew the exact number of atoms in the universe.
But also, I wish to understand Eddington’s philosophical perspective. So far, in the first three chapters, I have found his writing to be refreshingly engaging with the philosophy of science. Perhaps we should not be too quick to dismiss Eddington.
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He begins the fourth chapter with the following historical reminder:
“We have seen that the physicist is by origin a philosopher who has specialized in a particular direction; but for him epistemology had become ancient history, and he had long ceased to concern himself with it. Generally he prided himself on being a plain matter-of-fact person – which was his way of describing a man who accepted the naïve realism of Newtonian epistemology. If he indulged in philosophy at all, it was as a hobby kept apart from the serious occupation of advancing science.
Thus although scientific epistemology has always been part of the domain of physics, the physicist had left it so long uncultivated that, when at last he turned attention to it, his right-of-way was questioned. The re-entry into this neglected field was the beginning of the modern revolution of physics, the first result being the theory of relativity…” (p 50)
I will address his specific claims about Einsteinian relativity and quantum mechanics in the next two installments.
For now, let’s consider Eddington’s wider claims. The main arc of this chapter is to convince the reader that classical physics has been shown to erroneous in two respects.
The first error is one of empirical content. Classical physics has been falsified by numerous experiments. Experiments that modern physics can predict and explain. Therefore, we say that quantum mechanics and general relativity are both closer to the truth than classical mechanics (at least, in their respective large-scale and small-scale realms).
The second error, more important to Eddington, is one of philosophical assumptions. Eddington believes that classical physicists wrongly assumed (perhaps implicitly) that they were studying the objective world. Modern physics, he says, has abandoned this faulty philosophy.
…the characteristic of epistemological physics is that it directly investigates knowledge, whereas classical physics investigated or endeavored to investigate an entity (the external world) which the knowledge is said to describe. (p 47)
Thus, instead of attempting to form patterns about the objective world, modern physics aims to construct patterns between our perceptions of that world.
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Eddington’s repeatedly claims that classical physics was falsified by asking, in various ways, the same question:
What do we really observe? (p 51)
Once this is asked, Eddington asserts, we must conclude that epistemological considerations are able to replace physical theory. He goes into detail about how this is achieved by relativity theory and quantum mechanics in later chapters.
The more controversial question is, How far can this replacement extend? Here my conclusion, based on purely scientific investigation, is much more drastic than that of most of my colleagues. I believe that the whole system of fundamental hypotheses can be replaced by epistemological principles. Or, to put it equivalently, all the laws of nature that are usually classed as fundamental can be foreseen wholly from epistemological considerations. They correspond to a priori knowledge, and are therefore wholly subjective. (pp 53-54)
Eddington then draws a distinction between what we normally refer to as the ‘laws of nature’ – the patterns between our observations – and the parameters within these equations (the physical constants). In doing so, he makes a far bolder claim:
But in the more far-reaching investigations to which I am now referring, the constants as well as the algebraic forms are included. My conclusion is that not only the laws of nature but the constants of nature can be deduced from epistemological considerations, so that we can have a priori knowledge of them. (p 55)
One of his targets is the universal constant known as the ‘fine structure constant’, which I will deal with in a later installment.
Given that Eddington thinks that the algebraic form of our observations can be proven from epistemological methods, he is confident that these constants can be known with the same certainty.
…I think that progress of the epistemological method has assured us that the constants of nature (apart from our arbitrary units) are numbers introduced by our subjective outlook, whose values can be calculated a priori and stand for all time. For this reason my personal conclusion is that there is no more danger that the velocity of light or the constant of gravitation will change with time than that the circumference-diameter ratio π will change with time. (p 73)
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Let us return to Eddington’s parable of the fisherman, to understand why he would make such a claim. Eddington was of the belief that all the regularities we have discovered so far pertain to our sensory equipment, and not to the objective world. Thus, they are regularities that can be known with certainty because they do not really speak of objective laws.
All this progress [in physics] relates to subjective law. It all relates to uniformities imposed on the results of observation by the procedure of observation. As for the type of uniformity illustrated by the ichthyologist’s second generalization that all sea-creatures possess gills – uniformities intrinsic in the world around us – we have not even made a beginning. (p 59)
What then are the real objective uniformities? It is at this point that Eddington says something very strange. He makes a further distinction – a third category – of interest to physicists. Other than the ‘algebraic forms’ (equations) and the ‘constants’ (parameters) within these equations, Eddington considers the initial conditions (which he calls the ‘special facts’). He then declares:
To complete our knowledge of the universe we must know, besides the rules, the initial data to which they are to be applied. These data are the special facts. (p 59)
The objective regularities are then considered to be patterns amongst these special facts:
It is possible that we may discover a rule or regularity applying to the special facts. If so, we should probably not deny it the title of a law of nature. But it can be distinguished from the fundamental laws of nature, because it is no part of the scheme of prediction. It is just a pattern of the special facts gratuitously incorporated in the design of the universe. (p 60)
This seems to be an error. For what else are the regularities between the special facts other than the laws of nature!?
However, since Eddington considers our equations to speak about our knowledge of the objective world, he thinks that ‘special facts’ (perhaps synonymous with ‘observations’?) are not perfectly predicted by our physics.
The special facts, which distinguish the actual universe from all other possible universes obeying the same laws, are not given once for all at some past epoch, but are being born continually as the universe follows its unpredictable course. Moreover, in the differential equations of quantum theory the boundary conditions are not the objective facts but the knowledge we happen to possess about them. (p 60)
…it is not as in the deterministic days when the special facts were collected into a single instant. Within the limits of the uncertainty principle they are ever-changing as the moments pass by. (p 62)
And, he considers there are some facts masquerading as ‘boundary conditions’, and are in really part of the parameters of equations. Therefore, for Eddington, these too can be explained with epistemological methods.
We must therefore no longer look upon [the number of particles in the universe] as a special fact about the universe, but as a parameter occurring in the laws of nature, and, as such, part of the laws of nature. (p 62)
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Reading so far, I have come to consider Eddington’s position in relation to the other philosophers of science before him. Here is a broad historical development:
- Aristotelean: The laws about the objective world can be derived by purely a priori (logical) considerations.
- Baconian: The laws about the objective world need to be arrived at empirically.
- Einsteinian: Epistemological considerations can reveal some a priori characteristics about our own observation, from which we can better empirically construct physical laws. Theses laws do not speak of the objective world, but how it appears to us through our senses.
- Eddingtonian: Epistemological considerations can derive all the regularities in our observational knowledge (previously thought to be ‘physical laws’). All that remains for empirical investigation is to measure the ’special facts’ that feed the laws with our latest knowledge about the objective world.
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I think I am willing to go as far as Einstein, but not as far as Eddington. Especially when I consider his final remarks in this chapter, speculating where we might begin our objective investigations:
It seems to me that the “enlarged” physics which is to include the objective as well as the subjective is just science; and the objective, which has no reason to conform to the pattern of systematization that distinguishes present-day physics, is to be found in the non-physical part of science. We should look for it in the part of biology (if any) which is not covered by biophysics; in the part of psychology which is not covered by psychophysics; and perhaps in the part of theology which is not covered by theophysics. The purely objective sources of the objective element in our observational knowledge have already been named; they are life, consciousness, spirit. We reach then the position of idealist, as opposed to materialist, philosophy. The purely objective world is the spiritual world; and the material world is subjective in the sense of selective subjectivism. (pp 64-65)
This rings of the revelatory – something we might expect from a Quaker. This sort of talk is in clear opposition with methodological naturalism. Therefore, I must dismiss it on moral grounds.
Nevertheless, Eddington has been enormously thought-provoking so far, and I intend to finish his book. More to follow soon.
