Summary

This essay is an attempt to explain the relation between holism and a form of phenomenalism in terms of the difference between lego and meccano. The analogy is by no means complete, it is only meant to get the reader started in the right direction. Understanding what is meant by the phrase “the essential nature of phenomena” is not something that one can arrive at by considering things in themselves. The essay then goes on to describe a relational view of knowledge and to look at phenomenalist interpretations of quantum mechanics in the light of this.

Ernst Mach was the father of the form of phenomenalism which gave rise to logical positivism in the early part of the 20th century. He famously rejected the atomic hypothesis on the basis that atoms and molecules are not something we directly experience. Now, over a century later, some physicists are starting to accept the idea that quantum mechanics is a fundamentally phenomenological description of nature. This idea is not new: Niels Bohr was quite explicit about it and phenomenalism lies at the heart of the Copenhagen interpretation. But the Copenhagen interpretation has been widely criticised as not offering any kind of description of the ultimate nature of reality.

More recently Carlo Rovelli’s relational interpretation takes the physical content of quantum theory to be the relations that maintain between quantum systems. The so-called quantum state has no absolute meaning in this interpretation. The quantum state of a system is only something that exists in relation to some specified observer (i.e. some other quantum system), and that relation is itself something that is meaningful only to another observer.

A startling consequence of the relational interpretation is that different observers may give different accounts of the same sequence of events. This is not a problem, Rovelli claims, because when observers compare their observations, this is a quantum interaction and the formalism guarantees that no contradiction will result. The way this guarantee comes about is through the application of special consistency-checking measurements. These are quantum interactions which establish definite correlations between observing and observed systems. These correlations guarantee the consistency of specimen and and pointer states without destroying the phase information. The effect these consistency-guarantees is essentially semantic. In other words, these measurements establish the meaning of the physical interactions. These operators say that, for example, “either the specimen is in a state of spin-up and the ‘up’ light is on, or the specimen is in a state of spin-down and the ‘down’ light is on”.

Now there is no semantics without consciousness, so a consequence of this interpretation is that consciousness is not something that you can explain with quantum mechanics: consciousness is an invariant of the formalism. If quantum mechanics is a good description of the Universe, then consciousness is not itself a phenomenon, rather it is a condition of the Universe, like space-time. Thus it is not matter or energy but consciousness that is the fundamental substance.

This is surprising only if one expects all phenomena to reduce to (i.e. to be explained by) some more fundamental, essentially simpler parts. There is no experimental evidence that this is the case. In fact there is evidence from modern particle physics that the more we try to break down matter and energy into its fundamental constituents the more complex are the phenomena that we find.

I do not expect that Rovelli would agree with this analysis because he does not recognise the semantic role of his hypothetical consistency-preserving measurements. I also expect objections to my claim that there is no semantics without consciousness, but from a holistic perspective semantics and consciousness are two aspects of the phenomenon of perception. We get the idea of semantics whenever we consider a symbolic representation and its relation to the things it represents, just as we get the idea of consciousness when we consider the relation between the conscious states and the events to which they correspond.

This view of consciousness as the fundamental substance is not new. It is quite explicit in the earliest Buddhist philosophy. The teachings of Gautama Buddha were not written down until five centuries after his death, but they are said to contain a dozen accounts of causality (called pratityasamutpada) as a process which is essentially relational: this comes to be with the coming to be of that. This causality does not give rise to a partial order, like that described by classical physics. The logical form of Buddhist causality is that of a pre-order: one which may (will) contain causal loops.  In this causal picture one does not explain complex phenomena by pointing to their causes, reducing the Universe to some simple initial state. Instead, one starts with a simple, undifferentiated whole, which is consciousness, and then one explains the objects and their representations as co-arising within this. Meaning is therefore something inherent in the fabric of the Universe from the very beginning, not something that arises in a particular type of process that goes on in human brains.

Questions and criticism would be welcome.