Gestures in Empty Space

Gestures in Empty Space

Physics vs Philosophy
In the second half of his book On Physics and Philosophy Bernard d’Espagnat explores more of the philosophy and less of the physics of quantum theory, and I’m taking notes to keep track of where he’s headed.

In chapter 13 (“Suggestions from Kantism”) d’Espagnat says that physicists nowadays aren’t entirely sure how their scientific theories and results are to be interpreted.

Science of Reality vs Science of Phenomena
Immanuel Kant steered science away from “reality-per-se” and toward the study of phenomena, so d’Espagnat thinks Kant’s views might be promising.

Kant did not reject the idea of an underlying reality, otherwise he would have discarded the “thing-in-itself” concept.

Kant did, however, say that Pure Reason would not be able to make any pronouncements on it. Beliefs and speculations are fine as long as we don’t call them scientific or rational views, he said.

The Table vs the Representations of the Table
Here is a basic problem: if you look at a table you not only have a representation of that table somehow inside of you, but you also believe there’s a table somewhere out there.

Can we check that this representation is accurate? Well, we can’t check what’s “really” out there since our senses give us just a representation of the table.

Space vs Experience
Kant argued that the very concept of space and spatiality was “a priori.” We’re more or less born with it as we need to peg various bits of sense data somehow in relation to each other.

D’Espagnat disagrees, saying the same argument could be made about riding a bicycle or learning to swim. He says Kant, living in a time ignorant of the evolution of species, would also not have considered “learning by apprenticeship.”

That’s where systems of neurons gradually favour useful gestures and discard the unhelpful ones.

D’Espagnat finds himself not just rejecting the realists who argue for the “absoluteness” of space and time, but also the idealists who claim Kant pinned down the foundations of the argument.

Not just evolution but also quantum physics was lacking in Kant’s approach, yet even today philosophers consider a “demonstrated truth” the view that spatiality is just the mind’s way of framing phenomena.

Modern physics shows that concepts of Euclidean space, universal time, and precise localization are misleading, even if we need those concepts to operate as humans in our ordinary macroscopic lives.

Kant’s vs Quantum Theory’s Objective Language
In any event, Kant sees science as addressing phenomena, so his version of science is “weakly objective.” So is quantum physics, which speaks of experimental setups and predictions of experimental observations.

But Kant uses the language of objective reality with little modification, while quantum physics uses terms such as electrons and virtual particles for reasons of reluctant convenience.

Kant vs his Followers
Kant’s followers became much more hostile to the idea of an objective reality. Kant talked about the “thing-in-itself,” even if inaccessible to science directly. But neo-Kantians rejected the notion except as a “limiting concept.”

D’Espagnat looks at Ernst Cassirer, a neo-Kantian writing around a century ago. D’Espagnat says he may be the “clearest” of all the neo-Kantians.

Cassirer’s Concept of Concepts vs Traditional Concepts
Cassirer was very interested in the process of coming up with concepts.

He noted that traditionally a big concept contains little information because so many distinctions get blurred.

For instance, we can move from an oak to a tree to a plant to a living being, a concept so broad we hardly have words to describe it.

But with mathematics the bigger categories combine all the qualities of the smaller categories that feed into it.

For instance, the concept of second-degree curves doesn’t mean we can’t tell a circle from an ellipse any more. We just have to plug the right values into the right parameters and we can get a circle.

Logical Necessity vs Quantum Results
Cassirer tries to describe science as a mathematical approach incorporating more and more concepts through some sort of logical necessity.

Reason and the universal scope of logical necessity form the basis for some sort of Being.

But d’Espagnat says that’s just an analogy. If we look directly at quantum physics we see it doesn’t link disparate impressions into some sort of logically and causally required arrangement of entities.

Cassirer’s views on the rules of knowledge and logical necessity put great emphasis on our mental powers to create order rather than some reality “out there.”

Yet d’Espagnat reminds us that experiments often refute one theory or other, so there is something “out there” that can derail some view and just say “no.”

Complete vs Ongoing Pursuit of Knowledge
Furthermore, d’Espagnat’s concept of a “veiled reality” won’t leave us exasperated and depressed, he says, because we will always be able to come up with better and better ways to deal to generalize about phenomena.

Mind-independent Reality vs Internal Consistency
D’Espagnat says some modern philosophers with “Kantian or empiricist inclinations” are less resistant to the idea of an independent reality than Cassirer was.

D’Espagnat says that Hilary Putnam’s “internal realism” sees descriptions evaluated by some kind of “ideal coherence” that keeps our beliefs consistent with each other and with experiences represented in those belief systems.

But d’Espagnat says Abner Shimony thinks Putnam gives up too easily in rejecting any kind of correspondence between our senses and a “mind-independent or discourse-independent ‘state of affairs.'”

Shimony and d’Espagnat think the concept of a “protomentality” has some similarity with quantum mechanical concepts.

Bas van Fraasen came up with a “constructive empiricism” that rejected scientific realism. He said it might be useful to consider structures and processes not directly accessible to an observer, but they’ll have no intrinsic reality.

On the other hand, Fraasen said the issue of what is observable and what isn’t should be left to science not philosophy: the “Grand Reversal.”

Empiricism vs a Knowing Subject
But can Fraasen stay an empiricist when he’s making use of a “knowing subject”?

Shimony thinks empiricism needs to be dropped for some kind of realism — with a strong mental component.

In the end d’Espagnat agrees with Shimony that there must be some way to “close the circle” even if there is a “dark cloud” making the project difficult.

That dark cloud is the impossibility of considering quantum states to have an ontological status.

D’Espagnat says that as long as contemporary philosophers stick to philosophy they have trouble radically casting doubt on veiled reality, or even realism in general.

Only when modern physics is considered do we see how impossible it is to be a conventional realist.

Background image: NASA/JPL-Caltech/P. N. Appleton (SSC-Caltech) via


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