2
Just What is This Thing Called ‘Reality’, Anyway?
The Philosopher and the Scientist: Metaphysical Preconceptions and Empirical Data
It’s a cliché, but as I’ve grown older I’ve definitely become more impatient, more of an old curmudgeon. I’ve grown increasingly exasperated with our species’ seeming inability to learn anything at all from the past. This is certainly not an exasperation born of a nostalgia for the ‘good old days’. As anyone who grew up in the shadow of the Cold War and the threat of mutual assured destruction will tell you, there is no fondness for those times among those who survived them. Rather, this is an exasperation born from watching helplessly as the seemingly common sense and virtuous victories of decades of peaceful, liberal democracy are unravelled by a new breed of aggressive, opportunistic populists, intent on exploiting the legacy of a decade of economic hardship inflicted in 2008 by the greed of a few bankers. We seem to be at great risk of forgetting everything we’ve learned from modern humanity’s great successes and its horrific past mistakes.
My impatience knows no bounds. Much the same goes for our understanding of ‘reality’. I can’t begin to count the number of books and research papers I’ve read, the number of television documentaries I’ve watched, which purport to tell us how this or that scientific theory describes something new and unusually bizarre about reality, without ever being clear on the kind of reality that is supposedly being described.
Hang on. ‘Kind of reality’? What on Earth is that supposed to mean?
If you pick up an introductory text on philosophy, there’s a good chance that this will have sections on things like epistemology (the study of knowledge and justified belief), metaphysics (the study of the fundamental nature of being and existence, encompassing ontology and cosmology), logical reasoning, the philosophy of mind, moral philosophy, ethics and aesthetics, and the philosophy of science. If you look up ‘reality’ in the index, you’ll find that this is a subject discussed extensively under the heading of metaphysics.
So, to a philosopher, reality is metaphysics (meaning, literally, ‘beyond physics’). And yet, to a physicist, reality is something described by theories that are unquestionably scientific, such as quantum mechanics. What’s going on?
Now, there have been some well-known and very well-respected scientists who have publicly disparaged philosophy, ‘which at its best seems to me a pleasing gloss on the history and discoveries of science’, writes Nobel laureate Steven Weinberg.1 This kind of negativity is born from a judgement that philosophy appears to offer little or no guide to the inception, development, and evolution of a scientific theory, or even what it really means when we talk about the ‘scientific method’. ‘Let’s not put the cart before the horse,’ says Stanford University theorist Leonard Susskind, ‘Science is the horse that pulls the cart of philosophy.’2 ‘Of course, philosophy is the field that hasn’t progressed in two thousand years, whereas science has,’ says astrophysicist Lawrence Krauss, in a talk about his book A Universe from Nothing, an example of rather poor quality philosophy masquerading as science.3
Rather like the fractious members of the People’s Front of Judea in Monty Python’s Life of Brian, such scientists demand to know: ‘What has philosophy ever done for us?’
I confess I don’t really understand this kind of argument, or the attitudes that lie beneath it. So let’s be absolutely clear. Philosophy is not science. Philosophy does make progress, but this is not the same kind of progress that we tend to associate with science. It’s likely true that we can’t use philosophy to tell us how to develop a scientific theory, though I believe it holds some useful lessons, as we’ll see in the next chapter. This is, after all, what science is supposed to be for. But, as I hope to be able to show in what follows, when we look closely we find that it’s not actually possible to do science of any kind without metaphysics, interpreted broadly as the assumption of things we can’t prove. And the moment we accept this is the moment we open the door to philosophy.
As we’ve seen in the opening chapter, quantum mechanics forces us to confront some uncomfortable truths about what we can and cannot hope to fathom about the nature of reality. I firmly believe that if we want to understand how to interpret what quantum mechanics is telling us, then appreciation of a few lessons from philosophy is absolutely essential.4
So, let’s get back to reality. We’ll start by trying to discover what—if any—difference exists between the realities of the philosopher and the scientist.
Fans of the 1999 movie The Matrix will recall the scene in which Morpheus instructs Neo: ‘How do you define real? If you’re talking about what you can feel, what you can smell, what you can taste and see, then real is simply electrical signals interpreted by your brain.’5 Spend a few minutes pondering on this, and you should have no real difficulty in accepting its basic truth. You rely on your body’s sensory apparatus to deliver a complex set of sense impressions (converted into electrical signals) to your brain. As a result of some processes we do not yet fully understand, these impressions are synthesized in your conscious mind to deliver a set of perceptions and experiences (what some philosophers refer to as ‘qualia’) which combine to form a representation of the world around you. The result is what you call your reality. It is very specifically—and uniquely—yours.
You take this at face value because you have no real choice. If you went around questioning everything you perceive, then you wouldn’t get much done. Is this rose really red? Just what is ‘red’ anyway? Such questions concern your conscious experience, but what if you’re not around to experience things? If a tree falls in a forest, and there’s nobody around to hear, does it still make a sound? Is the Moon still there if you’re not looking at it, or thinking about it? And there goes another missed deadline.
You might want to argue that, after all, you are a highly intelligent life form, the result of about four billion years of evolution by natural selection on planet Earth, punctuated by at least five mass extinctions. Does it make any sense for Homo sapiens to have evolved a way of perceiving a reality that is in some way fundamentally different from, or inconsistent with, how it really is?
But then in another moment of quiet reflection you will realize that there is no evolutionary law you can point to that would guarantee this. One of the factors that contributes to the survival of a species in the hectic scramble we call life is that certain genetic mutations bring with them survival advantages that are then selected for. With any luck, you live long enough to procreate, hopefully passing these advantages to a new generation. All we can be sure of is that we’ve evolved a finely tuned mental representation of those aspects of reality necessary to ensure our survival. There is no evolutionary selection pressure to develop a mind to represent reality as it really is.
Unsure? Ponder the evidence from synesthesia, a condition in which those who experience it* report perceptions that have become ‘mixed up’, with stimulation of one sense triggering involuntary responses from one or more other senses. One fairly common form is known as grapheme-colour synesthesia, in which letters and numbers are perceived to be coloured: ‘Wednesday is indigo blue’.6 It’s easy to dismiss this as incorrect wiring or ‘cross-talk’ in the brain, giving rise to an incorrect representation of reality, but with a prevalence estimated to be about four per cent of the population, those affected do not always see it this way. Who’s to say whose perceptions are the ‘right’ ones?
And, before you ask, it’s no good trying to corroborate what you perceive by sharing your experiences with a friend. Unless they’re a synesthete (and you’re not), your friend will doubtless confirm that they perceive precisely the same things that you perceive: ‘Yes, that rose is red.’ But, even if we presume that your friend has a mind that works in much the same way as yours (and he or she is not a philosophical zombie), all this tells us is that both your minds have developed in a similar fashion. You learned about the colour red as a small child, perhaps from pictures in a book that your parents would point to whilst saying ‘red’ out loud. You can be pretty sure that your friend’s knowledge and understanding of colour is derived from a set of very similar experiences. All this tells us is that your minds have undergone much the same conditioning, producing what philosopher John Searle refers to as the ‘background’.
This problem with reality has been recognized by philosophers since the ancient Greeks. In The Republic, which was written nearly two and a half thousand years ago, Plato devised an allegory which we can re-purpose to explore the situation a little more deeply. This is Plato’s famous allegory of the cave.
Deep in the cave is a number of prisoners, chained to a wall. They have lived their entire lives in the cave, and have no experience of a world outside. They’re not even aware that they are prisoners.
It is dark, but the prisoners are nevertheless aware of men and women passing continually along the wall in front of them, carrying all sorts of vessels, and statues and figures of animals. Some are talking among themselves. But, in truth, there is a fire constantly burning at the back of the cave, filling it with a dim light. The fire is out of sight and the prisoners are completely unaware of it. The men and women that the prisoners can see against the far wall are, in fact, the shadows cast by real people passing in front of the fire. The reality that the prisoners experience is made up of the crude appearances of things—people and objects—which they have mistaken for the things themselves.
Plato’s allegory was intended to illustrate his three-tier theory of knowledge. The shadows represent common belief or popular opinion (doxa) based merely on appearances. The objects themselves represent a deeper form of understanding derived, for example, from science (episteme, from which we get ‘epistemology’). The topmost tier is noesis (or ‘nous’), knowledge that goes beyond the superficial facts of the objects and concerns their form and nature.7 But the allegory serves our purpose here as an illustration of the fact that, as human beings, we rely on our senses to deliver a representation of reality that we have learned to take at face value, if not for granted. In our everyday lives, it’s simply a waste of time to question everything we experience.
We should nevertheless acknowledge a simple truth. Our reality is made up of shadows, of things-as-they-appear, and we have no real way of knowing to what extent the representation shaped by our perceptions reflects reality as it really is, a reality of things-in-themselves.
So how then can we be sure that a reality of things-in-themselves even exists? Well, we can’t, but let’s fast-forward a couple of thousand years to 1781, and the great philosopher Immanuel Kant. In the Critique of Pure Reason, Kant distinguished between what he called noumena, the metaphysical objects of reality or things-in-themselves that we can conceive only in our minds, and the empirical phenomena, the shadows or the things-as-they-appear in our perception and experience.*
Don’t take this to mean that noumena are merely figments of a fertile imagination. I can imagine all kinds of entertaining things—such as Gandalf, unicorns, or Westeros—but these obviously don’t connect with phenomena; they don’t manifest themselves as things we can directly perceive, except in works of fiction.
More practically, we can point to lots of ways in which what we call ‘electrons’ manifest themselves in our empirical reality. These are electrons-as-they-appear. But an electron-in-itself without any kind of interaction through which it can make itself manifest exists, kind of by definition, only in our imaginations.
Kant claimed that it makes no sense to deny the existence of the things-in-themselves, as there must be some things that cause appearances in the form of sensory perceptions: there can be no appearances without anything that appears.* Just because we can’t perceive reality as it really is doesn’t mean that it has ceased to exist. The great science-fiction writer Philip K. Dick was surely paraphrasing Kant when he observed: ‘Reality is that which, when you stop believing in it, doesn’t go away.’8
But we have to accept a trade-off. Whilst we might happily conclude that the things-in-themselves must exist, we must grumpily accept that we can in principle gain no knowledge of these. When judged in terms of Plato’s three tiers, Kant denies that noesis is possible—we can never have knowledge of the form and nature of the things-in-themselves.
Now, in the last chapter we encountered another big disconnect, of a very different kind but no less profound. This is the disconnect between the quantum world of molecular, atomic, and subnuclear dimensions and the classical world of everyday experience. It is the disconnect created by the locked box of the wavefunction, measurement operators, and the collapse of the wavefunction. What we will discover is that our anxiety over the relationship between reality and perception carries over to that between reality and measurement. We will find that we can no longer assume that what we measure necessarily reflects reality as it really is, and that there is also a difference between things-in-themselves and things-as-they-are-measured.
The contemporary physicist and philosopher Bernard d’Espagnat called it ‘veiled reality’, and commented that ‘we must conclude that physical realism is an “ideal” from which we remain distant. Indeed, a comparison with conditions that ruled in the past suggests that we are a great deal more distant from it than our predecessors thought they were a century ago.’9
So, this is why philosophers consider any kind of speculation, any conception, discussion, dissection, or thesis on the nature of a reality of things-in-themselves, to be metaphysics.*
It’s probably about here that more pragmatic readers might be starting to lose patience. Philosophers are known for their tendency to argue, obfuscate, and confuse, to see problems where they don’t exist and make mountains out of molehills. This stuff about noumena and phenomena is all very well, but scientists don’t want to waste their precious time nitpicking over the meanings of words. ‘Physics’, the philosopher(!) Karl Popper once said in an interview, ‘is that!’, as he slammed a book down hard on the table in front of him.10
Science is surely different. It proceeds through the painstaking gathering of hard, reproducible, and verifiable facts. Scientists develop theories that can accommodate these facts and explain the patterns that they form in terms of some underlying laws of nature. These theories make predictions that can be tested by reference to new observations or experiments which generate new facts. Sometimes the new facts don’t fit, so the theory is either tweaked in some way or thrown out and replaced by a new theory. This is how science makes progress in ways that (at least according to Krauss) philosophy doesn’t.
Except that it’s not quite as simple as this, as we’ll see in the next chapter.
Okay, so we can never be sure that the reality that we perceive or measure reflects or represents the things-in-themselves, but this quite obviously doesn’t prevent us from making observations, doing experiments, and developing and testing scientific theories. We can still determine that if we do this then that will happen. We can still establish hard facts about the shadows—the projections of whatever we think reality might be into our world of perception and measurement—and we can compare these with similar facts that have been derived by others. If these facts agree, then surely we have learned something about the nature of reality?
And this is indeed the bargain we make. The philosophers tell us that reality-in-itself is metaphysics. Although scientists don’t often openly acknowledge it up front, the reality that they study is inherently an empirical reality deduced from their studies of the shadows. It is an empirical reality of observation, experiment, measurement, and perception; an empirical reality of things-as-they-appear and of things-as-they-are-measured. As Heisenberg once explained: ‘we have to remember that what we observe is not nature in itself but nature exposed to our method of questioning.’11
We’re not quite done yet. Scientists work best within a framework based on laws or rules. They need parameters. Even though we might not be able to gain knowledge of a metaphysical reality-in-itself, we can follow Kant (and Philip K. Dick) and assume that such a reality must exist. There can be no appearances without something that appears. What’s more, it must surely exist objectively and independently of our ability to perceive or measure it. We would expect that the shadows would continue to be cast on the wall whether or not there were any prisoners in the cave to observe them.
We might also agree that, whatever reality is, it does seem to be rational and predictable, at least within limits. It appears to be logically consistent. The shadows that we perceive and measure are surely not completely independent of the things-in-themselves that cause them; otherwise, anything goes and science of any kind would be impossible. Even though we can never have knowledge of the things-in-themselves, as Kant argued, we can assume that the properties and behaviour of the shadows they cast are somehow determined by the things that cast them.
The truth is that empirical reality is a pretty dull place. It is a reality consisting only of numbers, of effects, a reality of doing this and getting that. Imagine a research paper that says: ‘We did these things and we got these results.’ Full stop, end of story. The numbers and the effects are meaningless until we try to interpret them. To do this we construct a theory that tries to explain what’s going on, with the broad aim of improving our understanding. And I would argue that any kind of scientific theorizing is simply impossible without first assuming the independent existence and the rational, logical consistency of the reality that lies beneath all the bald empirical experiences.
What is the justification for these assumptions? At great risk of repetition, here’s that Einstein quote once again: ‘I have no better expression than the term “religious” for this trust in the rational character of reality and in its being accessible, to some extent, to human reason.’12
Scientists generally don’t think too long and hard or look too closely at these assumptions. Many regard them as intuitively obvious. But accepting these assumptions means buying into a specific philosophical position. This has a name—it’s called ‘scientific realism’. Curiously, those who don’t think about it at all can’t avoid making the same kind of commitment, knowingly or not, typically to an alternative but related position called ‘naïve realism’, a term which I’ve always thought to be rather pejorative. Like Monsieur Jordain in Molière’s The Bourgeois Gentleman, who discovers that he has actually been speaking prose all his life, so might some scientists discover that, at least in part, throughout their career in science they’ve also adopted a specific philosophical position, and so they’ve been doing philosophy.
Knowingly or not, most scientists are realists, although many don’t trouble themselves with grand questions about the nature of reality, which they’ll happily leave to philosophers. Although Einstein’s philosophy evolved through his early life, as far as quantum mechanics is concerned he was a realist,* as was Schrödinger (and Popper). Many years ago I trained as an experimental scientist and I can tell you it’s really difficult to work in a laboratory and maintain your sanity without some belief in the reality of the things you’re experimenting with.
So, let’s put our realist stake in the ground with a proposition (philosophers like propositions):†
Realist Proposition #1: The Moon is still there when nobody looks at it (or thinks about it).
This will actually save us quite a lot of time. In essence, it says that reality (whatever this might be) really does exist and, what’s more, it exists independently of our ability to make empirical observations and measurements on it. It continues to exist whether or not anybody is thinking about it. It is objective, not subjective. It doesn’t depend on me (or you) for its existence.
It’s important to acknowledge that, no matter how reasonable Proposition #1 might seem to you, it is nevertheless an assumption. What’s more, it’s an assumption that you will never be able to prove. Accepting this means admitting metaphysics into the very foundations of science.
Now we have to do something about the fact that quite a lot of science (and pretty much all of quantum mechanics) deals with things we can’t observe directly, but for which we gain empirical evidence that is indirect. These are things like photons, electrons, and quarks. These produce effects in our empirical reality of experience—such as interference patterns, lines in a cloud chamber, and ‘jets’ of hadrons observed at the Large Hadron Collider at CERN, which can be traced back to the behaviour of quarks and gluons, the force particles that hold quarks together inside protons and neutrons. We choose to interpret these effects in terms of ‘invisible’ quantum entities, and we ascribe to them physical properties such as mass, electrical charge, spin, flavour, and colour. We then explain the observable, empirical behaviour in terms of the properties we have ascribed to these invisible entities.
Let’s agree that, based on the above discussion, these properties tell us only about the things-as-they-appear or the things-as-they-are-measured, and we have no way of acquiring knowledge of photons-in-themselves or electrons-in-themselves, and so on. But this doesn’t prevent us from assuming that the things-in-themselves really do exist, independently of any instrument required to make measurements on them. For example, we see patterns of behaviour that we explain in terms of electrical charge. But electrical charge is merely the empirical manifestation of whatever property ‘in reality’ gives rise to such effects. This could very well be electrical charge as we understand it, but the truth is we have no way of knowing.
I propose to focus here on the reality or otherwise of the entities themselves, and set aside consideration of their properties for the next chapter. One of my favourite arguments for ‘entity realism’ comes from the philosopher Ian Hacking. In an early passage of his 1983 book Representing and Intervening, Hacking describes the details of a series of experiments designed to discover if it is technically possible to reveal the fractional electric charges characteristic of ‘free’ quarks (the answer, alas, is no). The experiments involved studying the flow of electric charge across the surfaces of balls of superconducting niobium:13
Now how does one alter the charge on the niobium ball? ‘Well, at that stage,’ said my friend, ‘we spray it with positrons to increase the charge or with electrons to decrease the charge.’ From that day forth I’ve been a scientific realist. So far as I’m concerned, if you can spray them then they are real.
Whilst Hacking is a realist about invisible entities, this doesn’t mean that he accepts that scientific theories about such entities are necessarily ‘true’. We’ll go on to consider the scientific representation of properties and behaviours in the next chapter, but as far as entity realism is concerned I discover that I can find no better words:
Realist Proposition #2: If you can spray them then they are real.
This should save us quite a bit of time, too.
You might be tempted to think that we’re now faced with a simple choice between the metaphysical reality of the philosopher and the empirical reality of the scientist. Some scientists and philosophers have indeed argued that this is a straightforward, black-and-white choice between metaphysics and empiricism. An outright rejection of metaphysics led arch-empiricist Ernst Mach to conclude that there could be no such things as atoms. In the 1920s and 1930s, a group called the Vienna Circle, led by philosophers Moritz Schlick, Rudolph Carnap, and Otto Neurath (and others), concluded that all metaphysics should be rejected as meaningless. They attempted to establish a scientifically based philosophy in which experience is the only valid source of knowledge. This is logical positivism, a kind of ‘seeing-is-believing’ brand of philosophy, which was directly influenced by Mach.14
But the fact is that Mach got atoms hopelessly wrong and the logical positivist programme failed.15 It is actually impossible to eliminate all metaphysics from science and, incidentally, this kind of realization is one way in which it is possible to see progress in philosophy. This is another reason why scientists inadvertently end up doing at least some philosophy, whether they are aware of it or not.
The problems arise just as soon as we try to go beyond the empirical evidence—the numbers, the effects, the doing this and getting that. Going beyond the evidence means opening the door to metaphysics. For the simple reason that it is impossible to engage in any meaningful dialogue about ‘why?’ and ‘how?’ without first developing some notions about the reality that we assume to lie beneath the empirical data. Scientists choosing this path have no choice but to indulge their inner metaphysicians.
This brings me rather neatly to the analogy I mentioned in the Preamble. To understand how science is done we need to recognize and respect the very distinct ways of thinking about reality adopted by scientists and philosophers, and the fundamentally important relationship that exists between them. I’ve tried to achieve this by conceiving of them as shores, separated by a sea, as illustrated in Figure 7.
Figure 7 A metaphor for scientific theorizing: sailing the Ship of Science across the Sea of Representation, between the shores of Metaphysical and Empirical Reality.
Giving flight to fancy, I think of the shores of Metaphysical Reality as idyllic. This is a warm, sunny, and welcoming place; of soft, sandy beaches and lush tropical vegetation. It is a place of abstract imagination and absolute perfection. Here you will find conceptions for how reality might be, could be, or should be. These are conceptions born from the personal values and prejudices of the individual scientists who visit, based on everything they have been taught and have come to understand about the nature of reality, and many things they can only guess at.
This is the place where scientists can be human—more Kirk than Spock. Here they can express their emotions, set free their desires, vent their frustrations, and just be themselves. Here it is possible to believe without evidence, to accept something as true without proof, to have faith. Some may look to find God here (in which case this place is a kind of heaven). Those scientists who prefer to deny the existence of God may instead look here to find nothing at all, because (for them, at least) conjuring something from nothing by physical mechanism alone represents the ultimate triumph of scientific (but actually just another kind of metaphysical) reasoning over religious superstition.
Such metaphysics might involve grand visions of reality, its cause, nature, and ultimate fate. But, on average, it is more likely to be concerned with some of reality’s rather more mundane aspects, the things-in-themselves and the ‘nuts and bolts’ required to assemble reality and hold it together.
You might be doubtful that scientists really need this place. Why should they want to come here? Surely they have everything they need in Empirical Reality? So let me try to illustrate why scientists find themselves needing to make frequent visits.
As we saw in Chapter 1, driven by otherwise inexplicable evidence, physicists of the early twentieth century were obliged to torture quantum mechanics from the classical mechanics that preceded it. As a result, our understanding of physical concepts such as linear momentum was profoundly and irreversibly changed. But some classical concepts were retained.
For one thing, the classical mechanics we inherited from Newton requires an absolute space and time. This is a problem because, if it existed, an absolute space would form a curious kind of container, presumably of infinite dimensions, within which some sort of mysterious cosmic metronome marks absolute time. It implies a vantage point from which it would be possible to look down on the entire material universe, a ‘God’s-eye view’ of all creation. The arch-empiricist Mach rejected this notion too, and Einstein arguably (and finally) dispensed with it in 1915 in his general theory of relativity, in which space and time emerge as dynamic variables.
Absolute space and time or, more correctly, absolute spacetime, is a metaphysical construction. And yet here it is still, dragged largely unchanged from classical mechanics to form the backdrop to a quantum mechanics, against which we imagine quantum events play out. Knowingly or not, anyone doing quantum mechanics is accepting the notion that reality consists of an absolute spacetime. They accept this without the benefit of any empirical evidence, its truth (or at least its acceptance) established without the need for proof.
Scattered along these shores you will also find the abstract, metaphysical concepts needed to lubricate the mathematical machinery of science. These are things such as the perfect circle and the perfect sphere; the infinitesimally small point; the infinitesimal angle; the infinite straight line; the natural limit; and many other things besides. These concepts do not exist in Empirical Reality, and yet without them we would struggle to do mathematically based science of any kind.16
For scientists who spend even a short amount of time here, all this gets bundled up into a set of metaphysical preconceptions. These summarize how scientists think about reality and the kinds of things they believe it should possess. They include preconceptions that might be based on abstract notions such as beauty, symmetry, elegance, or simplicity. They give rise to convictions that theoretical explanations should be ‘natural’. Or that reality must be deterministic, with effect always following inevitably from cause. Or that there are some unassailable ‘natural laws’ (for example, of conservation) that must always be respected. Or that spacetime must be absolute.17
Across the sea we find the shores of Empirical Reality. Now, this is the reality of our everyday experience, so I should apologize up front if you find the way I paint it to be intolerably bleak. Aside from anything else, I want to contrast Empirical Reality with the sandy, sylvan, alluring loveliness of Metaphysical Reality, and I’m mindful of Humphrey Davy’s homily about science being a harsh mistress, delivered to the impressionable young Michael Faraday, who on 1 March 1813 was newly appointed to a position at London’s Royal Institution.*
So, the shores of Empirical Reality are rocky and frangible, tormented by high winds and lashing waves. This is the inhospitable home of hard, if not rather brutal, empirical facts, of numbers and effects, of doing this and getting that. It is of course here where we discover how nature actually appears. This is where (supposedly according to Benjamin Franklin) gangs of brutal facts have been known to murder beautiful theories or, according to Thomas Huxley, we witness the ‘great tragedy of science—the slaying of a beautiful hypothesis by an ugly fact’.18 This is where scientists must set their emotions and their prejudices aside and practise a cold and calculating rationality—definitely more Spock than Kirk.
But don’t think for a minute that there’s no room for metaphysics, even here. We are obliged to accept that no observation or experiment is possible unless we have at least some idea of what we’re looking at, or experimenting on. Of course this doesn’t mean we can never discover new things, just that it is impossible to make an observation or a measurement without the context of a supporting theory of some kind, though that theory might change or be replaced entirely as a result.
French physicist and philosopher Pierre Duhem once suggested that we go into a laboratory and ask a scientist performing some basic experiments on electrical conductivity to explain what he is doing:19
Is he going to answer: ‘I am studying the oscillations of the piece of iron carrying this mirror?’ No, he will tell you that he is measuring the electrical resistance of a coil. If you are astonished, and ask him what meaning these words have, and what relation they have to the phenomena he has perceived and which you at the same time perceived, he will reply that your question would require some long explanations, and he will recommend that you take a course in electricity.
Empirical facts are never theory-neutral; they are never free of contamination from some theory or other. As we construct layer upon layer of theoretical understanding of phenomena, the concepts of our theories become absorbed into the language we use to describe the phenomena themselves. Facts and theory become hopelessly entangled: what we observe in Empirical Reality depends to a certain extent on how we look at it.
No wonder the logical positivists failed.
The shores of Metaphysical and Empirical Reality are separated by a sea. As I explained earlier, if we are to make sense of the empirical facts by developing explanations which deepen our understanding, we must find ways to bring together our preconceptions and the facts. We must create some tension between them. We therefore set sail in the Ship of Science, bringing all our metaphysical preconceptions with us and using our knowledge of the empirical facts to develop a workable representation of reality, or what we call a scientific theory. Our purpose in crossing the Sea of Representation is to find a way to accommodate both our preconceptions and the facts in a single, typically (but not exclusively) mathematical structure.
There are many different ways of making the journey across the sea, suggesting that it is indeed possible to develop many different theories, each with a different mix of preconceptions, and each of which provide perfectly adequate accounts of the empirical data. This is known to philosophers of science as the underdetermination of theory by data. It is a bit of a disappointment for anyone who thinks that science should deliver a description of reality that is unambiguously ‘true’, unquestioned, and fixed for all time.
And there you have it. Philosophers are content to contemplate and debate the nature of Metaphysical Reality, what purpose it might serve, and whether it has any real meaning or significance. They are philosophers, and do not concern themselves with the business of sailing aboard the Ship of Science.* In contrast, this is what scientists do. The ship ploughs back and forth on the Sea of Representation, refining metaphysical preconceptions here and gathering not-entirely-neutral empirical facts there, travelling in hope of a successful theory.
So let’s see how that might work.