Reality, physicists and philosophers have long assumed, must bottom out somewhere: in particles, fields, consciousness, or some other fundamental layer of being. But philosopher Emma Jaura, who is working on the foundations of quantum mechanics, argues that we should give up this quest for ultimate building blocks, and instead see reality as radically interdependent, where nothing enjoys absolute metaphysical priority, not even the universe as a whole. While this vision cuts sharply against the grain of Western thought, Indian and Chinese philosophy have explored how we might understand reality in this way for centuries. 

In order to understand our reality, we commonly find ourselves focusing on individual phenomena, zooming in on them until their “true nature” is revealed. An alternative approach is to zoom out, and redirect our attention to the connections between the phenomenon and others that surround it. Carlo Rovelli’s relational quantum mechanics (RQM) suggests that we take the latter approach, and paints a picture of reality where we can find a vast web of dependence relations that connect all sorts of unlikely parts of the universe. A striking feature of this picture is that amongst the phenomena connected through dependence, we can find no sign of any part of the universe that is ultimately fundamental.

Nothing is fundamental

It is natural to assume that there is some part of reality that is fundamental. Scientific and philosophical enquiry offer compelling explanations for what “underlies” our everyday experiences. It seems reasonable (and perhaps comforting) to think that the day will come when some phenomenon is uncovered that has nothing underlying it. Chains of explanation will finally come to an end, and the foundational and fundamental building blocks that give rise to all the things we experience will be exposed. Even if this ultimate discovery is never made by humanity, then it is common to think that these “fundamentalia” are still somewhere “out there.”

Whatever is fundamental, whether it be some form of deity or impartite particle, is supremely special. It violates Leibniz’s principle of sufficient reason, which demands some explanation of all existing phenomena in terms of something other. All things depend on it, whilst it depends on nothing. Hence, it is common to characterise fundamentalia in terms of metaphysical independence. Throughout the history of Western philosophy, the existence of some special, independent, fundamental phenomena has gone widely assumed, and under-scrutinized.

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Any physical system can play the role of an observer, regardless of whether it is a physicist with measuring apparatus, or even a being with consciousness.

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One thing that philosophers working on quantum physics tend to agree upon, is that the success of quantum theory over the past 100 years strongly suggests that we will need to accept some major metaphysical revisions, of some kind or other. One of the novel revisions that Rovelli’s relational interpretation of quantum mechanics suggests that we must make, or so I argue, is to the existence of some special, independent fundamentalia. A relational interpretation of quantum mechanics comes with a commitment to a relational view of all existent physical phenomena. This view suggests that all things are dependent for their existence and nature on something other than themselves, and as a result, nothing can exist completely independently. There is nothing ultimately fundamental.

This alternative to the typical picture can be called anti-foundationalism. The particular flavour of anti-foundationalism that results from a relational interpretation of quantum mechanics is one where a vast web of dependence relations connects phenomena, and structure reality.

Everything is relational

Those who aim to make sense of quantum phenomena are haunted by the measurement problem: the puzzle that surrounds the lack of determinate properties of quantum systems prior to their measurement. Before being measured or “observed” by a physicist, quantum systems lack properties like a certain location or spin direction. This mystery is deepened by the way that nature seems to become determined only when it is being observed. As Rovelli puts the problem: “why does nature care whether there is anyone to observe it or not?”

Rovelli’s relational interpretation parts ways from traditional or “textbook” quantum mechanics by offering a response to this puzzle, in a way that reframes it completely. His key suggestion is that any physical system can play the role of an observer, regardless of whether it is a physicist with measuring apparatus, or even a being with consciousness. When a non-conscious entity “observes,” or more accurately, “interacts” with a quantum system, then the quantum system’s properties are thereby determined. Not only that, but this interaction between two physical systems will determine both systems’ sets of properties, relative to one another.

This shift to thinking of properties becoming determined through “interactions” rather than “observations” puts relations at the heart of quantum phenomena. An interaction has an effect on both systems that interact. This means that all determined features of physical systems are relational, and that there are no properties that are independent from interactions. As Rovelli explains: “All variable aspects of an object exist only in relation to other objects. It is only in interactions that nature draws the world.” RQM therefore implies that there are no parts of our physical reality that are completely independent, or immune to external influences.

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This picture has a striking resemblance to that endorsed by some schools of Mahayana Buddhism.

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What does this mean for our metaphysical understanding of the world? Philosophers have suggested a number of options for what resides at the fundamental level according to a picture informed by relational quantum mechanics. These include suggestions that relations themselves are fundamental, events of interaction are fundamental, or even the entire universe as a unified whole is fundamental. I argue that each of these “foundationalist” options leads to some tension with when paired with relational quantum mechanics.

In essence, the problem with all three of these suggestions is the following: RQM rejects the existence of absolute states with independent properties, while commitment to any form of fundamentalia, whether they be relations, events or the universe as a whole, comes with a commitment to some absolute state, with independent properties. Monisms, like Jonathan Schaffer’s famous “priority monism”, where the universe as a whole is the one fundamental thing, commit to an absolute state which is the totality of the universe, and which itself has independent properties. Therefore, relational quantum mechanics is inconsistent with a view of the universe as a whole as the one fundamental thing.

Given that the universe in its totality has nothing external to interact with, RQM indicates that the totality cannot have a complete set of determined properties. Whilst this might sound counterintuitive, we can make sense of a lack of a complete, determined “whole” universe, if we recognise that interactions happen at the local level, and that systems have their properties determined relative to one another, internally. As Dorato puts it, “there is no consistent sum of all possible perspectives yielded by the parts, so that there is no definite One whose identity is non-relational or non-structural,” or as Rovelli puts it, “The externally observed world does not exist: what exists are only internal perspectives on the world which are partial and reflect one another.”

As for the other two candidates, relations and events, neither can be understood as completely independent, given the constraints of RQM. Events cannot be understood independently of their constituents (the things that interact or change during the event). Similarly, relations cannot be understood independently of their relata (the things that they hold between or relate). Given the upshots of RQM, objects and physical systems cannot have determinate properties independently. The result is that we get objects that are dependent on events (and vice versa), or we get objects that are dependent on relations (and vice versa). Either way, we end up with a picture within which no phenomena are independent, and therefore no phenomena are fundamental. Instead, reality is made up of a complex network of dependence, holding between non-fundamental systems. We get anti-foundationalism, and vast interdependence. (For further details of the argument, see Jaura 2024).

Webs of dependence

Metaphysical structures of reality that lack foundations, and embrace interdependence, are now receiving more attention from philosophers. Such accounts vary widely, with some committing to the extreme idea that two-way dependence relations hold between all existing things. This kind of all-pervasive interdependence leads to extreme claims, such that any two physical systems, no matter how distant, depend on each other for their nature. However, for those who’d prefer to avoid such outlandish claims, there are other options, where two-way dependence relations hold between some parts of the world, but not all. (Swiderski 2024 provides a delicious menu of the options available).

Whilst I remain undecided about whether RQM implies the most extreme of these pictures, I will say something in favour of all-pervasive interdependence, which may be of particular interest to the reader who is curious about the connections between science and religion. If it is the case that following RQM leads us to a picture of a web containing the maximum number of dependence relations between all things, then this picture has a striking resemblance to that endorsed by some schools of Mahayana Buddhism. One such school is the Chinese school of Huayan Buddhism, which offers a beautiful metaphor for the structure of reality, called the Net of Indra.

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The metaphor depicts all existing entities as bright shining jewels, each hung at an intersection of the latticework of an infinite net, stretched out across reality. Each jewel is cut in such a way that it reflects every other jewel across the net, with these reflections going on infinitely. In a similar way, the picture of extreme interdependence just described contains dependence relations connecting all existing entities across the universe.

Rovelli himself draws a parallel between RQM and the metaphysics of an earlier Indian Buddhist school, the Madhyamaka school, founded by the great Buddhist figure Nāgārjuna. Madhyamaka Buddhist thought endorses a picture of universal emptiness, in which all existing things are “empty” of their own intrinsic or independent nature. Nāgārjuna argues that all things are related through co-dependent arising, or pratītyasamutpāda. This kind of Buddhist picture is compatible with the extreme view that all things depend on all others, but does not necessitate it. The emptiness of all things is possible even when we have a world made up of a combination of cases of two-way dependence and cases of one-way dependence between phenomena.

Taking both interdependence and anti-foundationalism seriously could offer some benefits. In a society such as ours, where huge value is placed upon notions of independence, individuality, and self-sufficiency, which arguably contributes to a rise in social division and isolation, the impact of this picture could come with some welcome shifts in mindset. Such metaphysical revisions based upon RQM may come with a shift from looking inwards towards ourselves as beings with self-contained and individual identities, to looking outwards in recognition of ourselves as beings whose identity is constituted by everything that surrounds us.