Marxism and religion; quantum reality. Part I

Les Schaffer schaffer at SPAMoptonline.net
Wed Jan 3 13:32:55 MST 2001


[ bounced > 30 kB from Mervyn Hartwig <mh at jaspere.demon.co.uk>. Part I  ]

Sid:

Many thanks for your post on Marxism and religion attaching the very
interesting and informative article on Bohm. I think you have hit the
nail on the head re chauvinism and arrogance. This is not to say that
objective idealists aren't often ditto, but we should try to keep an
open mind where we don't really know...

I post herewith for the information of the list a take on the quantum
dispute by a Christian critical realist Marxist (reviewing a book by
another critical realist). This is not a cross-posting from the Bhaskar
List.

*****
review article
Doug Porpora
Quantum Reality as Unrealised Possibility

Quantum Theory and the Flight from Realism: philosophical responses to
quantum mechanics
By Christopher Norris. Routledge Critical Realism: Interventions series,
London 2000.
(ALETHIA 3:2, November 2000, pp. 34-39)

Christopher Norris' Quantum Theory and the Flight from Realism (QTFR)
was a difficult book for me to put down. When I did put it down, it was
to consult my old books on quantum mechanics so as to puzzle further
over the points Norris raises. QTFR is a demanding book, not because
Norris is unclear but because quantum phenomena themselves are so mind-
boggling and spooky. These qualities make quantum phenomena especially
important for realists to address. As Norris notes, quoting others
before him, a realist not worried about quantum mechanics 'has rocks in
his head' (87).

Challenging Copenhagen and postmodernism
Norris is at least one critical realist without rocks in his head. He
must, however, have fire in his heart. It took courage for someone
trained in literary theory to enter these murky waters to contest the
current consensus in physics. Norris evidently considered the stakes
worth the venture. The major thesis of his book is that it has been
precisely the elusiveness of quantum reality that has fuelled the
postmodern retreat from realism as a whole.

To combat this philosophical withdrawal, Norris seeks to show two
things. First, he seeks to show, against such philosophers as Michael
Dummett, W. V. O. Quine, and the oscillating Hilary Putnam, that not
even the orthodox view of quantum mechanics warrants a wholesale retreat
from ontological realism. As was demonstrated by the hoax played by Alan
Sokal on Social Text, the anglophone world is ever ready to be impressed
by French philosophers applying quantum level descriptors to non-quantum
reality. The French philosophers and those taken in with them should
read Michael Frayn's essay that appeared in at least my copy of the
program (playbill) that accompanies his dramatisation of the issues in
Copenhagen. There, Frayn makes clear what French postmodernists
typically do not. Memory and quantum behaviour may both be uncertain,
but the one sort of uncertainty has no bearing on the other. Any
connection is purely metaphorical.

The second thing Norris wants to show is more fundamental. He wants to
attack the impulse toward irrealism at its roots. That means challenging
the Copenhagen interpretation of quantum mechanics, according to which
quantum reality is uncertain and observer-dependent.

Challenging the Copenhagen interpretation is a tall order. Among
physicists, it has been the dominant understanding of quantum mechanics
from the start. After long debate with Niels Bohr, Einstein himself
failed to prevail against it. Einstein, we know, denied that God plays
dice with the universe. Among physicists today, the accepted wisdom is
that Einstein was wrong. At the quantum level of reality, the creator
evidently is running a bizarre crap shoot, one in which we observers
virtually make reality.

It becomes clear why realists should be worried. Norris' contention is
that the Copenhagen account must somehow be incomplete; that the physics
community has forsaken its scientific responsibility by contenting
itself with it; and that why physics has done so requires sociological
explanation (78).

At this point, I warn the reader, I make no pretense of expertise at
quantum mechanics. I can say I am the sort of interested, lay reader who
comprises one of the book's target audiences. To read the book, it helps
to be at least that. Unlike popular books on quantum mechanics, Norris
wastes no time taking the reader on a 'gee-whiz' tour of the weird,
quantum world. Instead, he gets right down to business, focusing on the
Einstein-Podolsky-Rosen (EPR) experiment and Bell's theorem. For those
of us who have been through it all before, the omission is a blessed
relief. For newbies, the ride may be rough.

As an interested, lay person, I propose in this review just to think
through some of the issues with Norris. I am convinced by Norris'
argument against those philosophers and postmodernists who extrapolate
inappropriately from quantum mechanics. However, I would quarrel with
some of the points Norris makes about the Copenhagen interpretation and
for various reasons remain somewhat more sympathetic to it.

Norris makes the point that quantum mechanics was formulated during the
heyday of logical positivism and that the Copenhagen interpretation
reflects this perspective. He further notes that many physicists have
been content to adopt an instrumentalist orientation toward quantum
mechanics. Both qualities are nicely illustrated in Copenhagen. At one
point in the play, Werner Heisenberg denies any reality to quantum
phenomena beyond the mathematics describing it. The mathematics, he
asserts, is the only deeper meaning there is. It is this positivist
complacency about underlying reality that Norris attacks, and in my
experience, many physicists still subscribe to it. To this extent,
Norris' complaint is merited.

I first encountered quantum mechanics in freshman physics. I was
immediately struck by the Heisenberg uncertainty principle and the
Copenhagen interpretation of it. To understand the principle, let us
begin with macro (non-quantum) reality. Social and behavioural
scientists in particular know that our observations themselves disturb
what we observe. Consider how television cameras will alter the
behaviour of the participants on Survivor or Big Brother. This threat to
validity is known as an instrument effect. In the physical realm at the
macro level, the instrument effect is often negligible. We see a
charging bear by the light that bounces off it. The impact of that
light, however, will hardly stay the bear's charge.

Now consider what happens when we try to examine the world's tiniest
objects, an electron for example. To examine an electron, we still must
do something that disturbs it. At this level, however, even minute
disturbances are consequential. The Heisenberg uncertainty principle
sets an upper bound on the certainty we can attain for two related or
'conjugate' properties of an elementary particle. To cite the most
important example, the more precisely we know an electron's position,
the less certain can we be of its momentum and vice versa.

This sounds straightforward and not especially spooky, but remember we
are now considering the world's smallest objects at rock bottom reality.
At rock bottom reality, nothing we do, no measurement advance, will ever
remove the minimal uncertainty identified by Heisenberg.

Epistemic vs alethic truth
This still does not sound so weird. The controversy begins with the
interpretation of the Heisenberg uncertainty principle. Here, Norris
makes an important contribution just by framing the issue in terms of
epistemic versus alethic conceptions of truth. This distinction Norris
borrows from philosopher William Alston (1996), and Norris applies it to
powerful effect.

The epistemic conception of truth is the conception shared by positivism
and postmodernism. It defines truth in terms of epistemic criteria.
According to the epistemic conception, truth is what is yielded by some
idealized way of knowing. When our way of knowing approaches the ideal,
we get truth. It is easy to see the connection with positivist
foundationalism. It is easy too to see the vulnerability of the
epistemic conception of truth to postmodern doubt. If there are no
certain methodological foundations, no unimpugnible methodological
ideals, then there is no truth.

In contrast, according to the alethic conception, truth is not defined
epistemically. Rather, truth is determined by the way the world is,
however we come to know that. According to the alethic conception, a
claim or belief is true if and only if the world is as claimed or
believed. It is the world or alethic truth that makes our claims true or
false and not our way of knowing which is the case. It follows that a
claim or belief may be true without our being able to demonstrate it.
Norris refers to this as a verification-transcendent understanding of
truth. Most of us who are critical realists endorse it.

Norris valuably spends some time showing the absurdities to which the
epistemic conception of truth can lead. If, for example, as Dummett
suggests, reality is what is true, and if truth is determined by our
ability to demonstrate it, then there must be gaps not just in our
knowledge of reality but in reality itself. If in principle we will
never know whether or not Jesus was born illegitimately, then it is
literally meaningless to suppose that he either was or was not. If our
knowledge cannot reach that far, then, suggests Dummett, neither do
ascriptions of truth or falsity. Norris nicely shows that this is not
only a peculiar position but one manifestly undermined by the history of
scientific discovery.

Norris argues that the Copenhagen interpretation of quantum mechanics
arose from applying an epistemic conception of truth to such matters as
the Heisenberg uncertainty principle. Norris (75-80) explains that
quantum mechanics was developed at a time of strong disillusionment with
determinism. We see this similarly reflected in the Frankfurt school's
critique of instrumental reason. The Copenhagen interpretation, Norris
argues, had affinities with this cultural sensibility.

To understand the Copenhagen interpretation, let us return to the
Heisenberg uncertainty principle. We saw that, according to the
Heisenberg uncertainty principle, there will always be an ineluctable
uncertainty about the precise values of any two conjugate properties of
an elementary particle. The question is what we make of this
uncertainty.

Applying, like Dummett, an epistemic conception of truth, Niels Bohr and
Heisenberg argued that if there is no way in principle for us to know
the precise values of two conjugate properties, then in reality they do
not have precise values. Instead, the properties actually acquire the
values they come to possess only when we observe them. Before that, what
exists is only a wave of 'potentia'1 that assigns each value a
determinate probability. According to the Copenhagen interpretation,
quantum phenomena do not obey deterministic laws but only invariant
probabilities. At the quantum level, reality is both stochastic and
observer-dependent.

I evidently was born a realist. Even in freshman physics, I remember, I
was disturbed by the above reasoning. I could understand that we could
not know the precise values of any two conjugate properties without
disturbing them. I further understood that this would entail an
inescapable uncertainty. I could not understand how it followed that the
properties had no precise values in reality. Even then, I suppose,
without knowing it, I subscribed to an alethic conception of truth. But
I had an exam to take, and I presumed the physicists knew more than I.
Yet, if I was so willing to shrug and go on, it was also because I saw
in the Heisenberg uncertainty principle the makings of a powerful,
polemical gambit. Like Bohr and Heisenberg before me, I was just then
beginning to become obsessed with the debate over free will and
determinism. What Bohr and Heisenberg were saying was that rock bottom
reality is nondeterministic.

In a number of places, Norris (e.g. 144-50) denies that the Copenhagen
interpretation of quantum mechanics provides any comfort to voluntarists
in the debate over free will and determinism. Norris is clearly thinking
of people like Roger Penrose who suppose that our capacity for free will
rests on some kind of quantum process. Against this, Norris (146-7)
points out, there is a huge difference between quantum randomness and
the responsible choice associated with human free will.

Non-identity of causality and determinism
Here is one place where I strongly disagree with Norris, and what lies
at the bottom of this disagreement leads to our divergent assessments of
the Copenhagen interpretation. Norris is surely right that responsible
human choice differs from the randomness of quantum mechanics. Thus, I
would further agree with him against thinkers like Penrose that human
free will is not likely to depend on quantum processes.

Still, I think Norris misses something here. He misses it even though he
reviews an argument of Elizabeth Anscombe, who makes the same point. The
relevance of the Copenhagen interpretation to the debate over free will
and determinism is not that consciousness itself will turn out to be a
quantum process. The point, rather, is that from physics itself we
receive support for distinguishing causality from determinism. This is
one, big, important crack in the positivist, covering law model of
explanation. As such, it establishes scientific precedent for denying
deterministic causality in the human sphere. Again, it is not that human
choice is now to be treated as random but that human reasons can now be
considered as causes even if, in a completely different way, they too
are nondeterministic. Although Roy Bhaskar (1975: 109) expresses his own
scepticism about the Copenhagen interpretation, he too acknowledges
that, if it is right, it strongly undermines the Humean account in just
this way.

There is, however, an even larger issue here that colours Norris'
treatment of the Copenhagen interpretation. As Norris shows, discourse
about quantum mechanics is often as ambiguous as the phenomena
themselves. On my reading, not even Norris escapes this ambiguity.
Specifically, on my reading, Norris tends to conflate two distinctions
that must be kept apart. The first distinction is between the
affirmation and the denial of independent reality. The second is the
distinction between a process that is deterministic and a process that
is only probabilistic. If we suppose that rock bottom reality must
necessarily be deterministic, then the probabilistic nature of quantum
mechanics renders it necessarily incomplete. But must a complete
description of reality necessarily be deterministic?

Because Norris continually assails the Copenhagen interpretation for its
contentment with incompleteness, he leaves the suggestion that a
commitment to reality requires at least eventually a deterministic
account. I do not agree. Although critical realism entails the
affirmation of reality, it does not entail any a priori specification of
the nature of that reality. I am prepared to have reality turn out
fairly strange. To me, it hardly seems a denial of reality per se to say
that at the quantum level, reality just is irreducibly probabilistic. In
fact, as a critical realist, I favour the idea. It provides a very clear
case of emergence, with more deterministic behaviour arising from
composition out of a lower level of probability.





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