An Introduction to Anti-Realist Positions on Quantum Mechanics

Philosophical Realism and Anti-Realism

Hilary Putnam defines what he calls “metaphysical realism” in very clear terms. In his Realism and Reason: Philosophical Papers, he states that the metaphysical realist believes that “the world consists of a fixed totality of mind-independent objects”. As a consequence of that, the realist also believes that “there is exactly one true description of the way the world is”. In addition, metaphysical realism is the position that “truth involves some sort of correspondence between words or thought-signs and external things and sets of things”.

Metaphysical realists also believe that the world has a “built-in” structure. In other words, we have a “ready-made-world”. Thus there must be (or can be) only one true theory of the world.

So what about anti-realism?

Anti-realism isn't only a position which can be applied to quantum mechanics or even to science generally. If anti-realism is primarily about observation, verification or “justified assertion”, then such things as counterfactual conditionals, other minds, the past, infinities, mathematics and suchlike are rendered problematic. Nonetheless, the usual argument in most of these cases (at least from “constructive empiricists”, etc.) is that such examples are “observable in principle”.

Simon Blackburn (as a “quasi-realist”) recognised these problems when he wrote the following:

“... let us suppose that some things lie outside observation: the past, or other people's sensations, or sub-atomic particles... I cannot display or make visible past events I talk about, the future ones, my own pains and thoughts, let alone electrons or numbers.”

So here, clearly, we must “manifest our understanding” (Michael Dummett's words) of such things in other ways. And we do so (in most of the cases mentioned) by relying on what's observable today or what's observable in principle. However, this is easier said than done in some cases, if not in all.

For example, we have observational evidence of the past today; even if we can't observe the past itself. As for “other people's sensations”, we can take (for instance) a quasi-behaviourist or Wittgensteinian position on this issue. Finally, we don't observe sub-atomic particles; though scientists certainly do observe patterns in cloud chambers and whatnot. And since this piece is about quantum mechanics, we can elaborate what's just been said about sub-atomic particles by saying that the standard anti-realist position is that statements about particles are actually (or really) statements about observables. In other words, all statements about (or references to) sub-atomic particles are simply “convenient fictions”.

Finally, the most important or relevant part of the anti-realist position (at least as it applies to science) is that it (to put it bluntly) doesn't accept the notion of truth when it comes to scientific theories and statements. To put some meat on that claim. Anti-realists emphasise what we can observe. And, in parallel to that, they underplay what's often called the “underlying causes” of what we can observe. Thus it's not that these underlying causes are said not to exist: it's just that we can never observe them. Or, at the very least, epistemically (or scientifically), and at this moment in time in our epistemic (or scientific) community, such underlying causes cannot be observed.

Realism in Physics

Scientific realism is well-defined by Bas van Fraassen. He wrote:

“Science aims to give us, in its theories, a literally true story of what the world is like; and acceptance of a scientific theory involved the belief that it is true.”

This gives us a position on those just-mentioned underlying causes: even if we can't, as yet, observe them. Thus there can be truths (according to scientific realists) about unobservable entities.

Famously, Albert Einstein took a very strong realist line on physics – specifically on quantum physics. He believed that science should tell us how the world is. He didn't believe that science is all about “empirical adequacy” (Bas van Fraassen), experiments, technological success, predictions and whatnot. Ultimately, then, science must also express truths.

Einstein's main problem was the clash between “instrumentalism” in quantum mechanics, and the crazy nature of some of its claims. Not only that: there were many different interpretations of quantum mechanics on the market place. Indeed many physicists didn't even get hot under the collar about these rival (or complementary) interpretations. That is, they didn't bother themselves with the “real nature of things”. Instead, they focussed all their attention on observation, accurate predictions, technological applications and whatnot.

In terms of a concrete example of Einstein's realism, we can take his position on Werner Heisenberg's uncertainty principle. Here we have a split between our knowledge of reality and reality itself. Alternatively, this can be seen as a split between epistemology and ontology.

Einstein admitted that we have limited knowledge of the position and velocity of an electron. However, he also believed that electron nonetheless does indeed have a definite position and a definite velocity regardless of our limited knowledge. Thus, in this instance, epistemology and ontology are dis-joined.

Anti-Realism in Physics

Scientific anti-realism and instrumentalism seem to simply re-express a position of Bishop Berkeley and others. That position being that we have no epistemic - or even ontological - right to move beyond what empiricists called “sense impressions” (or observations) to the “underlying true causes” of those sense impressions (or observations). That epistemic gap, of course, was at the core of modern scepticism; and, as a consequence, it turned various philosophers and scientists into anti-realists/instrumentalists and sometimes into various kinds of idealist.

Nonetheless, scientific anti-realists don't necessarily claim that underlying causes don't exist: it's just that we can never observe them. It follows from this, then, that certain brands of anti-realism are epistemological (i.e., not metaphysical) in nature. In other words, anti-realism is about what we can know and say, not about what is. That is, we can know about what it is we can observe, measure or experiment upon; we can't know about what is (as it were) “behind” what it is we observe. Thus, in scientific anti-realism, epistemology trumps metaphysics/ontology.

The American theoretical physicist and string theorist, Brian Greene, put this quandary here:

“... whether the uncertainty principle is a statement about what we can know about reality or whether it is a statement about reality itself.”

That first clause is a perfect expression of anti-realism. (That is, “what we can know about reality”.) That, of course, can be tied in with what anti-realist philosophers have called “verification”. This sets up a profound disjunction between metaphysical speculations as to “reality itself” and what we can know about reality. Thus, as a result of this, it can be argued that reality itself is (in Wittgenstein's words) a “wheel that can be turned though nothing else moves with it” - therefore it's “not part of the mechanism”. To put that another way: reality itself is roughly equivalent to Kant's noumena. In other words, noumena are the “ground” of our experiences or observations. Nonetheless, they are something we can't know anything about.

We can capture the anti-realist (or verificationist) position on quantum mechanics by simply emphasising the notion of measurement. Take Niels Bohr again. He believed that physics only deals with things which we can measure. In other words, in science there's nothing more than what we can measure; just as, to certain philosophers (from the logical positivists to contemporary verificationists), we can only speak about what we can observe or verify.

So perhaps we shouldn't get hung-up about what's often called “the true nature of reality” - specifically if it throws up conundrums which haven't (at least as yet) been solved.

The Swiss and American theoretical physicist Wolfgang Pauli went further than Bryan Greene by rejecting the opposition (i.e., between reality itself and what we can can know about reality) entirely when he stated the following:

“One should no more rack one's brain about the problem of whether something one cannot know anything about exists all the same, than about the ancient question of how many angels are able to sit on the point of a needle.”

Bohr too put this position when he said:

“It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we can say about Nature.”

Although I'm shoehorning terms from philosophy into physics here, this quote is also an almost perfect statement of anti-realism. In other words, what “how Nature is” is a metaphysician's dream. All we have is “what we can say about Nature”. And, at the quantum-mechanical level, what we can say in what we can say with mathematics. Consequently, just about everything else is analogical and/or imagistic. Indeed the analogical stuff can (or does) often mislead us. And perhaps it's also partly the source of quantum mechanic's "weirdness".

So this anti-realist position can be summed up by saying that something is indeed the case at the quantum-mechanical level. However, we can never know what it is. Indeed we can go even further than this and argue that it must follow that there's no "fact of the matter" about anything at the quantum-mechanical level. After all, can anything beyond what we can know be factual in nature or a candidate for truth?

Despite all that's been said, the quotes above are essentially about the attitudes physicists should (or do) uphold regarding nature or reality. In other words, there are no explicit claims about what does or doesn't exist. So here's where Werner Heisenberg made the next radical move when he said that

“atoms or elementary particles themselves are not real; they form a world of potentialities or possibilities rather than one of things or facts”.

However, there's a problem here. In one breath Heisenberg says that “atoms and elementary particles are not real”. Though in the next breath he talks about “potentialities or possibilities”. Thus was Heisenberg simply being realist about potentialities and possibilities instead of about atoms and elementary particles? Regardless of that, it's difficult to know what's meant by “potentialities or possibilities” when surely it must be something real which has such potentialities or possibilities. If we forgot the controversies concerning the “quantum vacuum” or quantum field theory here, the words “potentialities or possibilities” must be a reference to a something which has these features.

Interpretations

One can take a positive pragmatic (or instrumentalist) position on these interpretations of quantum mechanics. Alternatively, one can take a pessimistic position on them. Steven Weinberg takes the latter option. He writes:

“My own conclusion is that today there is no interpretation of quantum mechanics that does not have serious flaws. This view is not universally shared. Indeed, many physicists are satisfied with their own interpretation of quantum mechanics. But different physicists are satisfied with different interpretations. In my view, we ought to take seriously the possibility of finding some more satisfactory other theory, to which quantum mechanics is only a good approximation.”

Now is Weinberg's position philosophical/ontological in nature? Is he saying that it's not all about predictions, experiment, etc. – it's also about what is? In other words, is it a realist position on the interpretations of quantum mechanics?

David Finkelstein also notes the problems with these different interpretations; though he doesn't really hint at any metaphysical concern. He tells us that “[q]uantum theory was split up into dialects” and that this was the case because “[d]ifferent people describe the same experiences in remarkably different languages”. Consequently, this pluralism may seem fine except for the fact that all “[t]his is confusing even to physicists”.

Instrumentalism

Instrumentalism can be deemed to be a subset position of anti-realism with a particular relevance to science. 

For the instrumentalist, theories are seen as instruments which deal with what is observed in experimental situations. Thus theoretical terms or concepts are also deemed to be “fictions” which are instrumentally useful to scientists.

Instrumentalism can also be said to date back to the beginnings of modern science. This isn't to say, of course, that the word “instrumentalism” was ever used in the 17^th century or even that such scientists saw themselves as instrumentalists. Nonetheless, take the words of the Lutheran theologian, Andreas Osiander, in his unsigned preface to Copernicus's The Revolutions of the Heavenly Spheres. 

Osiander intentionally expressed an instrumentalist position on Copernicus's science in order to play down (as it were) the truth-claims contained within his book. (Osiander believed that such truth-claims would have clashed with aspects of Christian theology.) Osiander wrote (as quoted in A.F. Chalmers' What is this thing called Science?) the following:

“... it is the duty of an astronomer to compose the history of the celestial motions through careful and skillful observation. Then turning to the causes of these motions or hypotheses about them, he must conceive and devise, since he cannot in any way attain to the true causes, such hypotheses as, being assumed, enable the motions to be calculated correctly from the principles of geometry, for the future as well as the past. The present author [Copernicus] has performed both these duties excellently. For these hypotheses need not be true or even probable; if they provide a calculus consistent with the observations that alone is sufficient.”

In this quote it can be seen that there's a clear separation between what Osiander called “observation” and the “true causes” of those observations. Indeed it was said earlier that the notion of truth is sidelined by anti-realists. So here we have Osiander saying that Copernicus's “hypotheses need not be true nor even probable” if “they provide a calculus consistent with the observations that alone are sufficient”.

Thus, if Osiander were alive today, he would see quantum mechanics as a (mere) “calculus” which needn't concern itself with “true causes”. And that's exactly what many contemporary physicists do believe. Indeed we can go one step beyond that and say that instrumentalists deem particles and even atoms to be what's often called “convenient fictions”.

Conclusion: Options

It's possible to take up a position of anti-realism towards certain parts of science (or towards certain theories of science) and not towards others. Thus, since this piece is about quantum mechanics, then it can be said that one can be an anti-realist about the phenomena posited in QM yet not be an anti-realist when it comes to the everyday “classical world”. Of course this neat division of the micro/macro world comes up against two fundamental problems. One: the questioning of the micro-macro distinction when it comes to quantum mechanics itself. Two: the (as it were) theory-laden nature of statements about, for example, planets and even about whales or chairs.

People can also take the position called “semantic instrumentalism”. In other words, the terms used in quantum mechanics aren't taken as referring to literal entities. Instead, such terms are “logical constructions” (a term first used by Bertrand Russell) which are employed to make sense of the things we can indeed observe.

Anti-realists also argue that the statements which involve such terms aren't what they call “assertoric”. That is, they can't be either true or false. (Thus, I suppose, they can't be “factual” either.)

A middle way seems to be what's been called “reductive empiricism”. That is, what we observe is primary - even if what we observe doesn't include the theoretical entities of our theories. Nonetheless, the fact that we do observe some things which (at it were) hint at unobservables, that makes it the case that the statements within such theories are indeed assertoric.

Intertextuality or Philosophy Ex Nihilo?

How original can a philosopher's philosophy be? If it were utterly original (i.e., if it had no links to any previous philosophy), then perhaps it wouldn't be philosophy at all.

Take the “radicals” in the tradition of analytic philosophy.

Eliminative materialists and “anti-realists”, for example, needed to share some kind of a philosophical language with their contemporaries (as well as with the tradition), otherwise their chosen language and positions would have been inscrutable.

Perhaps at another possible world there are other philosophies which are completely alien to our own. We can now ask:

Why are “alien philosophies” philosophies at all if they share nothing with our own philosophies – i.e., if they're truly alien?

Schopenhauer once asked the following question (to paraphrase):

Why do philosophers never step outside books [or “texts”]?

Schopenhauer was very critical of the parasitical nature (as he saw it) of much philosophy. That is, he was critical of philosophers' reliance on other philosophers' texts. This was a philosophical point about what some Continental philosophers have called “intertextuality”. This term itself was coined by Julia Kristeva. However, let the semiotician Roland Barthes explain it:

“Any text is a new tissue of past citations. Bits of code, formulae, rhythmic models, fragments of social languages, etc. pass into the text and are redistributed within it, for there is always language before and around the text. Intertextuality, the condition of any text whatsoever, cannot, of course, be reduced to a problem of sources or influences; the intertext is a general field of anonymous formulae whose origin can scarcely ever be located; of unconscious or automatic quotations, given without quotation marks.”

Thus if Schopenhauer had spoken in contemporary terms, he might have said that (philosophically speaking) intertextual webs trap philosophers within them .

In response, the post-structuralist/deconstructor Jacques Derrida might have said that Schopenhauer was fooling himself if he really believed that he could escape from all the webs - or snares - of intertextuality. Derrida believed that we're all trapped within them (at least all Westerners are). And, as the fictional deconstructing car mechanic said to the analytic philosopher John Searle: "There is nothing outside the text.” (Il n'y a pas de hors-texte. - The apparently “correct” translation of Derrida's French doesn't help either.)

Philosophy Ex Nihilo

What would a philosophical a priori (as it were) be like? A philosophy untouched by other philosophies - untouched by other philosophical texts? Take the British broadcaster, politician and populariser of philosophy, Bryan Magee, and his account of his own ex nihilo philosophising:

“Until I went to university it never entered my head to associate any of these [philosophical] questions with the word 'philosophy'…I discovered that this is what they were…I had grown up a natural Kantian… I discovered…that I had been immersed in philosophical problems all my life.” [From Magee's Confessions of a Philosopher: A Journey Through Western Philosophy.]

What a strange passage that is. Magee wasn't claiming to be "outside language"; though he was claiming to have been outside philosophy. He was claiming that all of us are born with a kind of quasi-Chomskian Philosophy Faculty. However, if he wasn't claiming something about a universal philosophy faculty, then Magee must have been making a claim about himself - and himself alone. That claim must therefore be that Magee was somehow genetically programmed to philosophise in the particular manner in which he did in fact philosophise.

If the first option is taken (i.e., the quasi-Chomskian philosophising faculty), then many - if not all - young children (throughout the world) would be asking the same questions which Magee asked himself when he was a young child. It's of course true that many children do indeed ask philosophical questions. So which questions and problems was Magee talking about?

As Magee put it, he asked himself questions which he later realised were Kantian, Schopenhauerian, Leibnizian and Wittgensteinian in nature. If that's the case, then why weren't Kantian and Leibnizian - never mind Wittgensteinian - problems raised years before the birth of these particular philosophers? If these questions and problems are so natural (Magee claimed to be a "natural Kantian"), then why are they certainly not asked in other cultures in our own time (that's unless they come into contact with Western philosophy)? There may indeed be certain philosophical givens. (The American philosopher Thomas Nagel - in his book The Last Word - believes this to be the case.) Nonetheless, they certainly aren't, say, Kantian or Wittgensteinian givens. And any any givens (uncovered by empirical research) tend to be more theological, mystical or spiritual in nature; rather than (strictly speaking) philosophical.

It's of course possible that Magee was an incredible genius who not only came to Kantian questions and problems without the help of Kant; but to Leibnizian and Wittgensteinian problems and questions without their help too! (Rather modestly, Magee did claim that he didn't find "solutions for them".)

In the end it will be empirical research which will determine whether or not Kantian, Leibnizian, etc. problems and questions are really part of the philosophical a priori. From my own knowledge and reflections, I suspect that they aren't. Despite saying that, this doesn't devalue such philosophy in any way.

Intertextual Philosophy

So where did Kant's Kantian problems and questions come from?They largely came from other philosophers. And where did Leibniz’s Leibnizian problems come from? Ditto.

More clearly, Kant wouldn't have been a Kantian (ostensibly unlike Magee) without the problem of the impasse between Rationalism and Empiricism; as well as the scepticism of Hume. Schopenhauer wouldn't have been a Schopenhauerian (again, unlike Magee) without Kant and the work of the German Idealists who came before him (among other things).

Thus perhaps Magee simply felt inclined to squeeze his own childhood questions and problems into a Kantian hole.

Schopenhauer also saw himself in the way in which Magee saw himself. In other words, he saw himself as a kind of aprioristic philosopher. So Schopenhauer didn't only take a position on the a priori within philosophy; but also an a priori position towards philosophy itself. He thought that the best way to do philosophy isn't to read philosophical texts. Instead, it's simply to think and reason independently. (Wittgenstein also claimed this!)

Yet in his early life Schopenhauer confessed to being more or less obsessed with Kant. This must surely mean that Schopenhauer simply took an independent position on philosophy after the fact. He was like a car driver in a long car race who drives a car with an extra large petrol tank filled up to the brim. A driver who then claims to his fellow competitors that his car doesn't need any extra petrol. Yet, of course Schopenhauer partly - or even largely - lived off his memories of other philosophers' texts.

As for intertextuality as it applies to other philosophers.

Take William G. Lycan’s medium-length paper ‘The Continuity of Levels of Nature’: it includes fifty-two references to other philosophers’ texts. And, in addition, Jaegwon Kim’s ‘Supervenience as a Philosophical Concept’ has fifty-one such references.

And since two analytic philosophers have just been mentioned, it can be said that when a student of analytic philosopher thinks about the nature of the mind, all he primarily does is read and think about what, for example, Jerry Fodor and Daniel Dennett have said about the nature of mind. This must mean that he too may well be caught in his own intertextual trap. (Though, of course, it’s unlikely that any philosopher of mind would rely on just two philosophers of mind.) Indeed all his responses, reactions and commentaries on the nature of mind may also be largely intertextual in nature.

Thus when students study philosophy at university, it seems that reading texts often seems far more important than independent thinking and reasoning. Isn't this called “research”?

On the other hand, many philosophers (or wannabe philosophers) would like to flatter themselves with the view that their own philosophical views have occurred ex nihilo. However, genuine ex nihilo philosophical thought may be as unlikely as ex nihilo mental volition or action (what philosophers call “origination”). As I said, there may be some cognitive givens; though whether or not they're truly philosophical is open to debate. They certainly aren't Kantian or Wittgensteinian givens.

It can be asked where would the novice aprioristic philosopher get his concepts and tools from? Isn't it the case that he wouldn’t have the vocabulary to philosophise in the first place? Isn't it also the case that he wouldn’t even feel the need to ask philosophical questions without the spur of preceding philosophy?

As Derrida put it (in his 'Violence and Metaphysics' ) in a slightly different context (as well as to paraphrase):

The apriorist philosopher would still think or speak Greek.

Derrida himself - despite his deconstructions! - admitted to being a “Jew-Greek”. He said that he lived in a “house” which had been built for him by (religious) Jews and Christians; as well as by philosophical Greeks.