In Defence of Panexperientialism
Table of Contents
experience: n. & v. – n. 1 actual observation of or practical acquaintance with facts or events. 2 knowledge or skill resulting from this. 3 a an event regarded as affecting one (an unpleasant experience). b the fact or process of being so affected. – v.tr. 1 have experience of; undergo. 2 feel or be affected by (an emotion etc.).
(Concise Oxford Dictionary 1992.)
When I use the word “experience” I will be using it in a manner that is covered by none of the above dictionary definitions in any strict sense, though some of those uses do hint at it. The best I can do is to allude to my use through examples. There are visual experiences, auditory experiences, tactile experiences, gustatory experiences, and olfactory experiences. Hunger and thirst are experiences, as are vertigo and nausea. Pleasure and pain are experiences. Thoughts, emotions, memories, and anticipations are also experiences, as are hallucinations and dreams. Moreover, when I wish to refer collectively to the entire set of all such items of experience in any instant I will do so by use of the phrase “the field of experience” regardless of whatever arguments might be brought to bear against my employment of the term “field”.
The field of experience is in constant flux and divides into a collection of “experiences” (examples of which have been supplied above). This is the proper starting point for any investigation into the nature of that field, and this fact is often obscured by our human propensity to regard the world of our conceptual models as the “primary reality”. This proper starting point admits of a number of metaphysical views, each with its own characteristic problems. My aim here is to give one such view, namely panexperientialism, a fairer hearing than it often gets today. Some common misconceptions are cleared away, and it is shown that the characteristic problems accompanying this view are not fatal. Neither are they as serious as some of the problems accompanying competing views. Finally, support is garnered for panexperientialism from a number of sources, mainly (but not entirely) deriving from the manifest need for a new paradigm that is forced upon us by the quantum theory. For this reason I have appended a very brief overview of some relevant developments in physics since the close of the nineteenth century, but an understanding of these developments is not essential to an understanding of the main thesis presented below.
Objective and Subjective
objective adj. & n. – adj. 1 external to the mind; actually existing; real. 2 (of a person, writing, art, etc.) dealing with outward things or exhibiting facts uncoloured by feelings or opinions; not subjective. 3 Gram. (of a case or word) constructed as or appropriate to the object of a transitive verb or preposition (cf. ACCUSATIVE). 4 aimed at (objective point). 5 (of symptoms) observed by another and not only felt by the patient. – n. 1 something sought or aimed at; an objective point. 2 Gram. The objective case. 3 = object–glass.
subjective adj. & n. – adj. 1 (of art, literature, written history, a person’s views, etc.) proceeding from personal idiosyncrasy or individuality; not impartial or literal. 2 esp. Philos. proceeding from or belonging to the individual consciousness or perception; imaginary, partial, or distorted. 3 Gram. of or concerning the subject. – n. Gram. the subjective case.
(Concise Oxford Dictionary 1992.)
The use that I wish to make of these words is at variance with their traditional uses as stipulated in dictionary definitions and in much philosophical discourse. Although my use is unconventional, I believe it to eliminate some of the confusion that arises in discussions about experience. My use of these words will therefore require some explanation.
Mait Edey writes in his paper Subject and Object 1 that:
For purposes of this discussion, let the term ‘object’ refer to anything anyone might be aware of or pay attention to. The term refers, then, not only to ‘physical’ objects, including whatever material processes, states, or conditions one might discriminate, but also to such ‘mental’ or immaterial entities or processes as pains, sensations, memories, images, dreams and daydreams, emotions, thoughts, plans, numbers, concepts, moods, desires and so on. Whatever we may think about their ontological or epistemological status in other respects, I hope we can agree at least that any of these may be objects of attention or pass in and out of awareness.
The field of experience is comprised of such “objects”, which fall into categories with one such category being that of “people”. The world of objects comprising the field of experience gives an appearance that is consistent with the perspective taken by an entity that is itself embedded in that world, specifically an entity that is conceived to be a member of the category of “people”, and moreover a member that is unique amongst the members of that category inasmuch as it is a conceptual member rather than a perceptual member. This unique member of the category of “people” will be referred to as the “self-as-person”.
Some of the constituents of the field of experience (e.g. trees) are evident to all people that are in a position to observe them, as is indicated by their behaviour – e.g. two or more people looking at the same tree will normally agree that they are looking at a tree (even when one of those individuals is the conceived self-as-person). This particular set of constituents (comprised not only of people but also of all of the other objects that are evident to all people in a position to observe them, along with their relationships to each other) constitute what is conventionally referred to as the “objective world”, and this convention will be adhered to for the purpose of this discussion. Given Mait Edey’s description of the word “object” as outlined above, the word “objective” can no longer be considered a derivative. In an attempt to adhere to the more intuitively obvious use of these words I will reserve the word “object” for those constituents of the field of experience that comprise the objective world.
The objective world, then, is the world with which people are acquainted by virtue of those of their sense organs that are directed towards their immediate environment, and in the case of the conceptual self-as-person, the world that appears as that category of experiences conventionally referred to as “external sense data”. (I qualify these latter experiences as “external” only to distinguish them from those experiences associated with “internal” senses like proprioception, the feelings of thirst and hunger, etc.) Data acquired through the external sense organs are described as “empirical”, and it is by virtue of the common form of external sense organs amongst members of our species that aspects of the objective world may be considered “shared” or “public”. For this reason the phrases “objective aspects of experience” and “empirical data of experience” will be treated as synonymous for the purpose of this discussion.
Some of the constituents of the field of experience (e.g. pain, hunger, etc.) are not parts of the objective world unless divulged via some kind of objective behaviour such as language, pain behaviour, etc. Such constituents relate only to the conceived self-as-person, and comprise what is conventionally referred to as the “subjective world”. To continue with the use of words as stipulated above, subjective experiences are non-empirical. On these definitions, and at variance with common use, the terms “objective” and “subjective” identify certain categories into which the constituents of the field of experience fall.
“Other Minds” and Solipsism
mind n. & v. – n. 1 a the seat of consciousness, thought, volition, and feeling. b attention, concentration (my mind keeps wandering). 2 the intellect; intellectual powers. 3 remembrance, memory (it went out of my mind; I can’t call it to mind). 4 one’s opinion (we’re of the same mind). 5 a way of thinking or feeling (shocking to the Victorian mind). 6 the focus of one’s thoughts or desires (put one’s mind to it). 7 the state of normal mental functioning (to lose one’s mind; in one’s right mind). 8 a person as embodying mental faculties (a great mind).
(Concise Oxford Dictionary 1992.)
When I use the word “mind” I will be using it in a manner that is covered by none of the above dictionary definitions in any strict sense, though some of those uses do hint at it. My use of the word “mind” will be synonymous with my use of the phrase “field of experience” as described above.
Language is a mode of behaviour that serves in permitting people to influence (and to be influenced by) the behaviour of other people, principally between two or more people residing within the same linguistic community since language use is communally inculcated. It has been argued that language can pertain only to the constituents of the objective world and can gain no purchase upon the constituents of the subjective world (this is an interpretation of Wittgenstein’s argument against the possibility of a “private language”). But it is often the case that a specific subjective experience is consistently associated with a corresponding objective experience to the extent that certain modes of behaviour exhibited by another person (other people being objective constituents of the field of experience) are accepted as evidence by association of the corresponding subjective constituents. So when another person exhibits e.g. pain behaviour (as an objective experience), pain (as a subjective experience) is commonly imputed to them. In this manner words like “pain” acquire a kind of double-meaning, permitting subjective experiences to be spoken of (albeit with a certain ambiguity). This propensity to impute subjective experiences to other people is instinctive in humans, and we call this propensity empathy.
The field of experience, then, includes the native conviction that every other person is associated with subjective experiences, and it would follow from this conviction that every other person would be associated with a field of experience that similarly divides into an objective world and a subjective world. To put it another way, just as the field of experience encompasses the conviction that it is associated with a unique conceived person inhabiting the objective world, so all perceived people inhabiting the objective world are, by extension, conceived to be associated with fields of experience. It is, as it were, an inductive inference based on a single sample, and so it is possible to call this default assumption into question, and this is known as the “problem of other minds”. The first consideration, then, must be the question of whether or not the field of experience is “all there is” – i.e. whether or not there is a domain “beyond” the field, so to speak. To assume no such domain would conflict with the instinctive conviction of the existence of other fields of experience (or “other minds”) – i.e. since the fields of experience associated with other people do not appear as constituents of the field of experience associated with the self-as-person, and since the assumption above would deny them any existence “beyond” the field of experience associated with the self-as-person, then how could they exist at all? In accepting the instinctive conviction of the existence of other fields of experience I am rejecting the view known as metaphysical solipsism, and I hereby declare my prejudice against that view.
The Status of Science
It is useful to simplify compound systems by reducing them to the collection of parts that comprise them. In understanding the parts and how they relate to each other, we gain a better understanding of the system and thereby enhance our ability to make accurate predictions regarding the behaviour of the system. This is such a successful way of thinking that we may be enticed into the belief that the whole is nothing more than the sum of its parts – a view known as reductionism. People undoubtedly benefit from their tried and tested understanding of how the objective world works – i.e. how its parts relate to each other within a reductionist framework. Familiarity with the lawful operation of this “machinery of the objective world” is of the utmost importance for our survival within that world and for our ability to successfully manipulate that world to our own advantage, and so pursuit of this kind of knowledge has become paramount. This pursuit singles-out empirical data as grounds for hypothesis creation and returns to empirical data in order to eliminate some subset of competing hypotheses, and this methodology is widely accepted as a central plank of science as that word is commonly used today. It is understandable, then, that many people have come to conceive the objective world, along with the conceptual world-model that accompanies it, as the “primary reality”, and a reliable understanding of it is the driving ambition that has culminated in the scientific enterprise. In short, the objective world has become the point of departure for most human considerations – the starting point. But recall that it was not the starting point for this discussion – the starting point for this discussion was the field of experience that is constituted in part by the objective world and the accompanying conceptual models.
Discussions about the field of experience could not take place unless the idea of the field of experience had first appeared amongst the constituents of that field. Unlike most ideas, this idea does not depend upon any particular constituent of that field (i.e. upon some aspect of the subjective world or, more pertinently, upon some aspect of the objective world), and so, just like the subjective experiences that partly comprise that field, this idea must also be classed as non-empirical. The non-empirical nature of subjective experiences, along with the non-empirical provenance of the idea of the field of experience, renders them both strictly intractable in terms of scientific investigation. Scientific investigation is constrained to address only the objective world, and so the scientific world-model is necessarily a partial model. Our inclination to take that model as the starting point for our investigations sometimes carries forward to our attempts to investigate subjective experiences or to investigate the idea of the field of experience, but it should now be clear that to do so is to transgress the remit of scientific investigation.
Talking about Consciousness
consciousness n. 1 the state of being conscious (lost consciousness during the fight). 2 a awareness, perception (had no consciousness of being ridiculed). b (in comb.) awareness of (class-consciousness). 3 the totality of a person’s thoughts and feelings, or of a class of these (moral consciousness).
(Concise Oxford Dictionary 1992.)
When I use the word “consciousness” I will be using it in a manner that is covered by none of the above dictionary definitions in any strict sense, though some of those uses do hint at it. My use of the word “consciousness” will be synonymous with my use of the phrase “field of experience” and with my use of the word “mind” as described above. I will speak of “instantiations of consciousness” in the same way as I speak of “individual fields of experience” or of “individual minds”.
Since the idea of the field of experience does not have an empirical provenance and is not abstracted from anything that does have an empirical provenance, the success of any attempt to use language to refer to this idea will depend solely upon whether or not it can be consistently associated with some aspect of the objective world (i.e. some aspect of human behaviour). If no such aspect were to exist then any attempt to refer to the idea of the field of experience would not be subject to the conditioning process that goes on within linguistic communities (and by which such communities maintain a practical level of linguistic consistency), and the idea must properly remain outside the domain of language use. Although it seems that the word “consciousness” is often recruited to allude to the field of experience, this use of the word is not strongly subject to the normal mode of communal linguistic conditioning, and the same word is often used to refer to ideas that do indeed have an empirical provenance (such as when the nurse informs the surgeon that the patient has “regained consciousness”). Nevertheless, for the purpose of this discussion I will employ the word “consciousness” synonymously with the term “field of experience” on the pretext that the rich history of discussions along these lines permits sufficient confidence in the conviction that all people are associated with fields of experience (or alternatively with “instantiations of consciousness”).
It may rightly be argued that, because of this weakness of linguistic conditioning, two people discussing consciousness (on this use of the word) can have no confidence whatsoever that they share a mutual understanding of how the word is being used, and this often seems to be the case when attempting to follow debates about consciousness. But in some cases this mutual understanding does seem to obtain, and I submit that this is because some people have acquired the idea of a field of experience and have inferred from context that others are recruiting the word “consciousness” in order to allude to it. It may be the case that some people have not acquired the idea of consciousness and so employ a variant use of the word without realising their shortfall. It may also be the case that some people that have acquired the idea of consciousness have prejudicially discarded it in favour of a variant use of the word. So the hazard in such discussions is that this confidence in a mutual understanding may be misplaced, but I will proceed on the assumption that I have given sufficient context for my use of the word to permit those with a compatible understanding to have a well placed confidence that this use of the word is indeed mutual.
Note that it would clearly be a mistake to claim that consciousness appears within the field of experience as a subjective experience or even as the entire category of subjective experiences, unless we are stipulating a technical definition of consciousness that is at variance with the definition that has been given above.
The Mind/Body Problem
There is a clear association between the conceived self-as-person and the idea of the field of experience, and this association has been the subject of much discussion in the Western world ever since Descartes brought it to the fore in the seventeenth century. This is the infamous “mind/body problem”, where the word “mind” is being used to refer to the instantiation of consciousness (field of experience) assumed to be associated with a particular “body” (i.e. a living person, in just the same way as the word was used when referencing the “problem of other minds”). The “problem” is that of providing an explanatory account of how mind and body relate to each other.
It should be clear by now that any claim that consciousness (or “mind” as the word is being used here) is amenable to scientific investigation would either be a claim based on a variant use of the word “consciousness” or else an error of judgement (possibly originating in our propensity to consider the objective world as the primary reality, the starting point for such an investigation, misleading us into putting the cart before the horse). Given that consciousness does not admit of analysis by those methods employed to investigate empirical phenomena, it would seem that all attempts to find a solution to the mind/body problem will entail metaphysical hypotheses rather than scientific hypotheses – i.e. hypotheses that cannot be eliminated on empirical grounds but only on grounds of logical inconsistency.
Any attempt to find a solution to the mind/body problem must treat consciousness as either an object, a property, or a process, regardless of the fact that consciousness does not appear anywhere within the field of experience (i.e. as an item of experience). To seek an explanatory account of consciousness in this manner would be to imagine a “bigger picture” within which consciousness plays a role (i.e. to imagine it as a part amongst other parts), but a “bigger picture” that cannot be justified on grounds of logical necessity or on grounds of empirical evidence. Furthermore, our default assumption – that every person is associated with an instantiation of consciousness – is inessential for all practical purposes (regardless of our instinct for empathy). The upshot is that the very idea of treating consciousness as an object, property, or process may be in error, but unless this assumption is made, I cannot see how to progress further with this discussion. The task, then, may be considered a recreational activity, inasmuch as it has no value in helping us to negotiate the objective world or to manipulate that world to our advantage.
In prejudicially rejecting metaphysical solipsism, my present position is that the minimum metaphysical configuration consists of a multiplicity of minds (instantiations of consciousness, fields of experience). My principal interest here concerns the set of minds that manifest as perspectives upon a common objective world, since any other kind of mind would have no role to play in any explanatory account of this set. The problem I face at this juncture is that of the inter-relatedness of minds – i.e. how it is that all of these distinct minds come to share a perspective upon a common objective world. The most prevalent view today is that there is a domain in addition to this multiplicity of minds, a domain comprised of something that is not mind (not consciousness) – something called “matter”. According to this view, distinct minds come to share a perspective upon a common objective world because the objective world (as it appears in the field of experience) is a mere facsimile of a perspective taken upon a material world that putatively exists independently of minds – i.e. a world that would exist even if there were no minds to register it in experience. I will refer to this view as materialism. This, in turn, raises further problems regarding the relationship between mind and matter – i.e. how consciousness could possibly have emerged in a world that was initially devoid of it (the “emergence problem”), how the human organism generates its associated instantiation of consciousness (the “generation problem”), how the perceived world might exert any influence upon the constituents of consciousness and similarly how the constituents of consciousness might exert any influence upon the material world (the “interaction problem”). These problems are not trivial and have been dealt with extensively by others without satisfactory resolution (see Griffin), so I am taking the trouble here to investigate the alternative to this view – the view that there is no such material world. This brings me back to the problem of how all these distinct minds come to share a perspective upon a common objective world.
By consigning materialism to the sidelines, I am now subscribing to the view that a person and its associated mind are different aspects of a single entity – a view known as dual aspect theory – and turning my attention to the idea that objects are nothing more than constituents of minds (i.e. nothing more than objects for a mind or for minds). That is to say that there are no “things in themselves”, or objects having a mind-independent existence. By virtue of the appearance of people as constituents in the minds of other people, and by virtue of the assumption that body and mind are different aspects of a single underlying entity, human minds may now be considered to include each other in a manner that accounts for their inter-relatedness – i.e. entities that exhibit the dual aspects of body and mind may now be considered immanent within each other by virtue of bodies (other people) appearing in minds. They can be said to be mutually immanent. But this does not yet provide a sufficient account of the existence of the shared objective world as it appears in the field of experience, firstly because that world also includes objects other than people, and secondly because any particular mind would frequently be devoid of other people. This calls into question any assumption that the only class of objects to be associated with minds is that of people. The next step, then, is to consider what kinds of object may be associated with minds.
There is nothing contentious about accepting on face value the instinctive conviction that all people are associated with minds, and perhaps nothing too contentious about extending that assumption to all anthropoids on grounds of structural similarity. But to go much further becomes controversial. It might be argued that there must be a threshold at some point on the phylogenetic scale, the location of which would depend upon structural similarity or dissimilarity, but this claim can be nothing more than a matter of prejudice given that even our grounds for imputing minds to other people cannot be given empirical support. The bottom line is that there is no justifiable argument for denying minds to even non-anthropoids – e.g. I could extend the claim without inconsistency to all mammals, and indeed to all animals throughout the phylogenetic scale, right down to the single-celled protozoa. Furthermore, if there are no logically consistent grounds for denying minds to animal cells then why not to plant cells? I could even continue on to the cellular organelles, and further still to the molecules that comprise them. And if the argument applies to molecules then why should it not apply to atoms, and even to sub-atomic particles? The particular view to which this line of reasoning leads was championed by Alfred North Whitehead and has been given the name panexperientialism. A common argument arraigned against this view confuses mind with cognition – an argument that rejects the idea that e.g. cells might be associated with minds on the grounds that a single cell is incapable of cognition. It should be clear, however, that this is an incoherent objection – a mind need not encompass cognition, or even emotions. The constituents comprising any mind that might be associated with a single cell need not be as rich as those accompanying a person.
The Combination Problem
I’m now faced with the problem of how a collection of minds, each mind being associated with an object within a cohesive system of objects, can combine to yield a single over-arching mind that is associated with the system as a whole – e.g. cells combine to yield an organism, so how do the minds of the cells combine to yield the mind of the organism? This objection is known as the “combination problem” and was first raised by William James as “the mind dust problem”. The reductionist paradigm presupposes that the components of a compound system are ontologically distinct entities bound together into a cohesive framework by means of “the forces of nature” (gravitational, electromagnetic, and the weak and strong nuclear forces). However, the idea of mutual immanence entailed by panexperientialism implicates an underlying wholeness by virtue of parts appearing within each other in a kind of global network that will be referred to as the “all-in-all”, and this idea suggests how this problem might be resolved. Any compound system, or cohesive collection of objects, will entail that each member of that collection plays a strong role within the minds associated with each of the other members of that collection. The strength of coupling between objects comprising a compound system would vary between different kinds of compound system. There is a sense in which the molecules in a bacterium cell might be considered strongly coupled and the molecules in a grain of sand weakly coupled, and this would be reflected in the strengths of the roles played by other members of a system within the mind of each member of that system. Thus the mind associated with the bacterium cell (regarded as a collection of interacting molecules) would be relatively well defined in comparison with the mind associated with the grain of sand, the latter being perhaps too nebulous to warrant serious consideration as a distinct mind. Systems that are too nebulous to warrant serious consideration in terms of an over-arching mind will be referred to as aggregates.
This presents us with a set of connected “hierarchies of minds” where each hierarchy can be envisaged as a pyramid having its most simple constituents at its base and a single over-arching mind (associated with the compound object) at its apex, and (in contrast to the reductionist view) no member of the hierarchy being any more “fundamental” than any other. So panexperientialism introduces a holism that counterbalances the reductionist view, and the components of any compound system would already be connected by virtue of that holism. (It is interesting to note that this may also suggest a solution to the “binding problem” in neuroscience, possibly considered problematic only because of the reductionist paradigm that is so dominant in human thinking.) A common argument arraigned against panexperientialism is that it would assign minds to entities such as tables and chairs, but it should be clear that this is an incoherent objection since such entities would best be considered as aggregates rather than cohesive compound systems, and therefore too weakly coupled to be associated with distinct minds.
The Boundaries of Panexperientialism
The continued existence of any object is rendered certain only during unbroken periods of its appearance within the field of experience, but given the idea of mutual immanence, an object’s continued existence would be ensured by its appearance in any field of experience provided these appearances overlap. However, it is possible that this overlap may, for some particular object, be broken – i.e. a particular object may be absent from the minds of all other objects for some small duration (between its interactions with other objects). Not only would the object be absent from all other minds for this duration, but also the mind associated with the object, being devoid of constituents for this duration, should also be considered absent. Consequently the object and its associated mind might justifiably be considered to have “dissolved back into the underlying wholeness” for this duration. The idea of a conventional trajectory between the point of its dissolution into the wholeness and the point of its subsequent precipitation out of the wholeness (i.e. its next interaction) would then be inappropriate.
The characteristics of the precipitating object would have to be sufficiently consistent with the characteristics of the dissolved object if it is to give the appearance of being the same object – consistent, that is, but not necessarily identical (a trivial example would be that the precipitating object will in all likelihood have a different spatial relationship to other objects and thus appear to some of those objects to have moved). Regarding the attributes of the precipitating object, this scenario would permit a range of possible values that could be assigned to certain of those attributes – i.e. values that would all be consistent with it being the same object that had previously “dissolved” – but for which only one value can be actualised (i.e. observed or measured).
(Note that this would be consistent with the stochastic character of the measurements or observations of the kinds of objects studied in quantum physics and which gave rise to the idea of “wave function collapse”, thereby engendering the measurement problem. It should be noted that the scenario outlined above pertains only to objects that are simple enough to undergo periods of non-interaction with any other object, and so would render impotent Schrodinger’s attempt to subject the “Copenhagen Interpretation” of quantum mechanics to a reductio–ad–absurdum by use of his famous “cat-in-a-box” thought-experiment. It may also be pertinent to the “Quantum Zeno Effect”. See appendix 1.)
All hierarchies within the all-in-all can now be seen to resolve downwards (on the pyramid analogy) to a common base-layer comprised of quantum objects. Also, the apex of any hierarchy implicated in a compound object will most likely be a member of a more encompassing hierarchy, and this kind of layering would continue upwards until all such hierarchies converge either upon a single apex associated with the entire all-in-all, or upon a set of such apexes that collectively constitute an aggregate.
Within our conceptual model of the objective world, the spatial relationships between objects engender the idea of “space” as a reified theatre within which objects have their existence, and (consistent with materialism) within which such objects exist whether or not they are experienced. But the objective world itself consists of a category of the constituents of consciousness, and in panexperientialism there is nothing other than instantiations of consciousness. The conception of “space” consistent with materialism, then, has no role to play in panexperientialism, even though spatial relations still obtain between objects appearing within any particular instantiation of consciousness.
A particularly interesting consequence of panexperientialism would pertain to pairs of objects that are related in such a manner as to have certain correlated attributes but that have both dissolved into the wholeness (i.e. temporarily ceased to appear as objects within any instantiation of consciousness). When either one of those objects precipitates in some instantiation of consciousness or other (i.e. when, from a human perspective, a “measurement” has been made upon it), reducing its observed attributes from the range of possible attributes to a collection of actual attributes, the correlated attributes for the other (as yet unexperienced or unmeasured) object would immediately be reduced in accordance with those of the measured object. (This would be consistent with the nonlocal aspects of the quantum theory. See appendix 1.)
Within our conceptual model of the objective world, the temporal relations between events engender the idea of “time” as a reified theatre within which events have their existence, and (consistent with materialism) within which such events exist whether or not they are experienced. But the objective world itself consists of a category of the constituents of consciousness, and in panexperientialism there is nothing other than instantiations of consciousness. The conception of “time” consistent with materialism, then, has no role to play in panexperientialism, even though temporal relations still obtain between events appearing within any particular instantiation of consciousness.
I started out by describing the field of experience as “in constant flux”, which is as much as to say that I consider change to be as fundamental as experience. But the way we speak about the changing nature of experience misleads us into thinking about change in terms of our conception of “time” – i.e. as a kind of spatialized representation of change that divides into past and future separated by “the present instant”. Our most successful conceptual models employ this spatialized representation of change in order to create an explanatorily useful four-dimensional “block universe” model of space-time (Minkowski’s contribution to Einstein’s Special Theory of Relativity). But this model leads us to conceive the cosmos as if it were frozen inside a glass block, not only devoid of change but also devoid of any privileged “now” that could exhibit any such change by virtue of its passage through the block. The original acknowledgement of change becomes difficult to accommodate in this view without begging the question. The block universe model therefore leads us to the view of time known as eternalism in which change is considered an illusion, whilst leaving this putative illusion without satisfactory explanation. However, the demise of simultaneity in Special Relativity would seem a compelling reason to entertain this view. Panexperientialism, however, entails a view of time known as presentism in which there is only the “present instant” (the privileged “now”), and this view is clearly in conflict with the demise of simultaneity entailed by Special Relativity. (Finally, for completeness, the view known as possibilism must be mentioned, which reifies the past and present but not the future, permitting future events to be undetermined to some degree.)
Versions of materialism entail either no instantiations of consciousness at all (eliminative materialism – a view that dismisses consciousness as an illusion but that leaves this putative illusion without satisfactory explanation), or a multiplicity of instantiations of consciousness that are coordinated by their embeddedness in a more fundamental material (i.e. non-conscious) world (a view that leaves that embeddedness without satisfactory explanation). According to materialism, then, the world unfolds independently of any consciousness of it, rendering the past immutable whether or not any aspect of that unfolding was experienced. In panexperientialism, however, there is no “material world” that exists in the absence of any consciousness of it, and so the constituents of consciousness are constrained only to exhibit consistency across all instantiations of consciousness by virtue of their mutual immanence. So the all-in-all entailed by this mutual immanence unfolds as a unified process that is complete in itself, devoid of the unexperienced events in the past that are characteristic of materialism. The presentism entailed by panexperientialism stands in contrast to the eternalism entailed by Special Relativity, rendering the Minkowski model of space-time a useful mathematical construction that reveals its limitations down at the quantum level. (Indeed, this scenario would be consistent with Suarez’s “before-before” experiment. See appendix 1.)
In panexperientialism, “the past” consists of nothing more than certain established states of affairs in “the present” – i.e. in the all-in-all as it unfolds as a unified process that is complete in itself. The upshot for panexperientialism (and in contrast to materialism) is that, in some supposed history, any events that were not themselves constituents of the objective world as it then appeared in some instantiation of consciousness or other would not yet exist. Only when some correlated event becomes actualised (in “the present”) would the possibilities for any associated but unexperienced past event be reduced. So, for the most part, past events would be implicit in the constituents of the all-in-all, but there would also be possible past events that would not be implicit in those constituents because they had never actually been part of the objective world as it appeared in any instantiation of consciousness. Thus it might appear that aspects of the past can be “created” in the present, and this raises the possibility of empirical testability. (Indeed, this scenario would be consistent with Wheeler’s “delayed choice” experiment. See appendix 1.)
When regarded only from the reductionist standpoint (i.e. from the typically human perspective), it is understandable that we may fail to discern any logically necessary connection between distinct “events in time” just as we may fail to discern any logically necessary connection between distinct “objects in space”. Thus any connection between causally related events cannot be accounted for in terms other than those of habitual association (as initially pointed out by David Hume). But it is the reductionist standpoint that leads us to assume that events are ontologically distinct, and this standpoint is called into question when we introduce the notion of mutual immanence. The wholeness implied by mutual immanence yields a single unfolding process that is complete in itself, but that divides into a multiplicity of distinct objects interacting with each other in a multiplicity of distinct events. So now the connection between causally related events (the “cause” and the “effect”) should be viewed as the conceived stages of an otherwise unbroken process. In terms of that implied wholeness (and consistent with the results of the Suarez “before-before” experiment – see appendix 1), all notions of spatiotemporal causal mechanism would be rendered meaningless. In panexperientialism, then, instantiations of consciousness do not causally interact with each other – rather their harmonization is a consequence of their mutual immanence. The idea of causation is part of the conceptual world model that appears as part of the constituents of consciousness – i.e. it is an artifact of human psychology.
Realism with respect to a class of objects is the view that the objects in the class are real in contrast to their being useful or convenient fictions. Science tells us that perceptual objects like trees and rocks are comprised of more fundamental conceptual objects like protons, neutrons, electrons, etc. and scientific realism is the view that such conceptual objects should, in the reductionist spirit, be considered as real as the perceptual objects they comprise. One may also be a realist with regard to “the past”, “the future”, “other minds”, etc. However, postulating the existence and nature of some non-experiential “reality” that supposedly underpins the world of experience is not science but metaphysics, and has often led to erroneous conceptual models. Consequently I will stipulate my use of the word “real” in such a manner as to implicate anything that makes a practical difference in our lives – i.e. we might confer “reality” upon those objects (both perceptual and conceptual) that impact upon us in a predictable and repeatable manner, even if this means that we confer reality only on a provisional basis. I will refer to this as pragmatic realism to distinguish it from what I will call materialistic realism – the metaphysical doctrine that the “real” world is independent of any consciousness of it. Pragmatic realism makes no such metaphysical demand.
In pragmatic realism the moon is considered real because it affects our daily lives, whether or not it would continue to exist in the absence of any consciousness of it. On grounds of their explanatory power, protons, neutrons, and electrons are also considered real (note the technological advances that have been enabled by advances in particle physics), but there is a fly in the ointment here. We are inclined to consider “real” objects to have precise attributes at all times, just as we conceive trees and rocks to have. Adapted to our environment as we are, we believe objects to continue to exist even when nobody is looking at them. In the case of predators that have disappeared from view, our lives may depend upon that belief. So given the notion that there could be some particular duration in which absolutely nobody was looking at the moon, we still believe that the moon continues to exist with some precise size, mass, and location in space for that duration. This belief is supported by related effects that continue to be observed, like the moon’s tidal influences upon the world’s oceans. A consequence of this is our innate conviction that all objects continue to have precise attributes whilst between observations, and that any inaccuracy in our knowledge of the attributes of such an object is a consequence of our inability to make sufficiently precise measurements upon it. But developments in physics have seriously challenged this conviction in respect of the continued existence of quantum systems whilst between observations (see appendix 1). This brings out the metaphysical aspect underlying that conviction and challenges this metaphysical position in the particular case of quantum systems, but it does not challenge the pragmatic belief in the continued existence of classical (i.e. non-quantum) objects. The consequences of classical objects going absent between direct observations would be far more grievous than that of, say, an electron going absent between interactions, provided that electron interactions remain lawful.
So, if by reason of innate prejudice we confer “reality” only upon objects that are conceived to exist even in the absence of any consciousness of them (materialistic realism), then panexperientialism clearly does not qualify as a form of realism. But if by reason of linguistic convention we confer “reality” upon those objects (perceptual and conceptual) that impact upon us in a predictable and repeatable manner, then subscribing to panexperientialism presents no obstacle to considering objects such as the moon, trees, and rocks to be real. However, quantum objects (such as electrons and photons) whilst between interactions might still fail to qualify as real, but this would be of no consequence to our practical lives and so would not undermine pragmatic realism.
Hilary Putnam has argued that, since the conceptual objects of science have tremendous explanatory power, it would be a miracle if these objects were not real. We should take care here to maintain our distinction between pragmatic realism and materialistic realism. I take the word “miracle” to indicate a violation of the consistent orderliness that obtains between constituents of the objective world – i.e. miracles are violations of the “laws of nature”. Any relationship that might obtain between the entire field of experience and whatever might putatively be “beyond” it (and responsible for the orderliness that manifests within it) is not a “law of nature”. The orderliness that obtains within the field of experience (i.e. between the constituents of consciousness) is a necessary precondition for the possibility of useful explanation, and the human propensity to seek explanation transgresses its limits when it seeks an account of why such explanation is possible at all. The upshot is that panexperientialism is realist in respect of other minds and is consistent with pragmatic realism in that everyday objects like trees and rocks may be considered real. It may also be considered consistent with scientific realism given that conceptual objects such as galaxies and atoms may be considered provisionally real (i.e. real unless and until new evidence comes to light that would call that ascription into question). Consequently we should be suspicious of any impulse to reject panexperientialism on grounds of our innate materialism.
There is, however, a credible argument that undermines the view presented in this account, and this is the most convenient place to consider that argument1. Special Relativity Theory predicts that a system of photons has zero mass when the photons are all travelling in the same direction, but that the system has non-zero mass when the photons are not all travelling in the same direction (see Appendix 2). If this is indeed the case then, just as tidal influences on the world’s oceans provide evidence that the moon continues to exist when nobody is looking at it, so the acquisition of mass in systems of photons would provide evidence that photons continue to exist between their interactions.
The Concept of Self
This is a muddled concept that demands some analysis if the confusion is to be cleared away. It has been divided below into four distinct concepts, the first of which has already been introduced:
1. The Self as the Person
The notion of “self-as-person” was introduced in the section above entitled “Subjective and Objective”. This is the notion of self as a member of the category known as “people”, or more specifically as the conceived human organism in its habitat. Note that (i) the idea of the field of experience, (ii) the idea of the self-as-person (the human organism associated with the field of experience), and (iii) the problematic association between these two ideas (the mind/body problem), are all constituents of the field of experience. However, the broader unqualified concept of “self” is complicated by other ideas that also appear as constituents of the field of experience, namely the “subject of consciousness” and the “agent of action”.
2. The Self as the Subject of Consciousness
There is an innate idea of “being a subject” over and against the objects that constitute the field of experience, the subject being “that which is experiencing” the constituents of that field. However, this idea is but another constituent of the field of experience, and the question arises as to how this idea might be accounted for. The main problem is that the constituents of the field of experience are in constant flux, and there is no single entity amongst those constituents that could possibly qualify as the “enduring subject”. One approach to this problem is to propose that the subject is a metaphysical entity existing in some putative domain “beyond” the field of experience. Another approach is to conclude that this idea is an innate misconception and to seek a possible source for the misconception.
Whatever the mechanism by which this idea is generated, the idea complicates the useful concept of self-as-person by accreting upon it the idea of self-as-experiencer (or as the “subject of consciousness”); more specifically the idea of a “something” that somehow experiences the field of experience. No such object appears amongst the constituents of the field of experience, and neither does anything that does appear amongst those constituents give any grounds for such a concept. The idea that one portion of the constituents of experience somehow “experiences” another portion of those constituents is difficult to sanction, and also raises the question of how there can be any experience of the experiencing portion itself – i.e. the idea of an experiencer entails an infinite regress known as the “homunculus problem”. Note that rejecting as a misconception the idea of self-as-experiencer would eliminate to the notion of direct acquaintance with the constituents of experience (or immediate knowledge of them), since there would then be nothing other than the constituents of experience for which any such relationship could obtain. The upshot would be that there is no “observer” of subjective experiences, since the term “observer” would then only pertain to the self-as-person in respect of empirical data concerning its environment. (Note that this would be consistent with the foregoing rejection of the possibility of a “science of consciousness”.)
3. The Self as the Agent of Action
Objective biological processes are sufficient to account for much of our behaviour – e.g. eating, drinking, procreating, avoiding injury, etc. Not only are such “biological drives” accompanied by subjective sensations (e.g. hunger, thirst, pleasure, pain, etc.), but they are also accompanied by a conviction that this correlation between the biological drive and the associated subjective sensation is causal in nature – i.e. I eat because I’m hungry, drink because I’m thirsty, etc. That is to say that I consider myself to be something more than just an organism in its habitat – a something that can envisage possible future outcomes, that has preferences in regard to those possible outcomes, and that directs the organism to behave in a manner that aims to meet those preferences. So when I say “I lift my arm” I mean something more than merely that the self-as-person (the conceived organism) lifts its arm, since there is a conviction that this “I” (the something more than just the organism in its habitat) is an active process that intervenes in what would otherwise be an entirely automatic process. There is a conviction that this “I” receives information from sense organs, processes it in conjunction with stored information, and issues outputs that direct the activity of the organism’s skeletal muscles.
This “I”, then, is conceived in such a manner that, given prevailing conditions, it has the capacity to envisage a number of possible future outcomes and to cause the organism to behave in such a way as to favour some preferred subset of those outcomes, and this mode of behaviour might usefully be referred to as “willing”, or more commonly “the will”. Consistent with this idea of being something more than just a biological machine, we have a propensity to speak of our conscious decisions in contrast to our automatic (or unconscious) actions, as though consciousness were some kind of active participant in our behaviour (in contrast to the way the word is being used in this document). Moreover, this way of thinking implies that this active “consciousness” is in some sense “free” of the dictates of the organism’s otherwise automatic responses, thereby rendering “me” an agent rather than just a biological machine. So, conceptually at least, “I” (as agent) can choose a course of action that favours some preferred future outcome.
The fly in the ointment here is the provenance of “my preferences.” It would seem that these preferences are determined by (i) membership to a particular species (human instincts), (ii) personal history (conditioning), and (iii) the ability to work from premises to conclusions (reasoning). Of these three categories of behaviour, it would seem that only the third category is a suitable candidate for the term “conscious deliberation” and therefore a suitable candidate for the activity of the agent. But given that my ability to work from premises to conclusions permits me to envisage possible future consequences of my behaviour and to behave in a manner that favours one such outcome, that conclusion still fails to account for my preference for a specific outcome. If the only way such preferences can be accounted for is in terms of instincts and conditioning, then reasoning is just an extension of these automatic biological processes and operates in accordance with those processes. Indeed the reasoning process itself, rather than conferring some kind of “freedom”, would appear to be a constraint on behaviour, preventing the organism from behaving inappropriately with regard to future outcomes (otherwise this “freedom” would reduce to randomness and would fail to account for the orderliness of our “willed” actions).
The conceived “self-as-agent” in this process seems to be redundant. If this is the case then the “conscious” of our “conscious decisions” implies nothing more than (i) that reasoning is a process that is active within the field of experience, and (ii) that reasoning is ascribed therein to a “reasoner” (or “thinker”) that is conceived as being distinct from the organism (self-as-person). But this conceptual divorce of “the reasoner” from the organism has no solid foundation – it is the organism that reasons, and so the notion of self-as-agent would appear to be nothing over and above the self-as-person. The conceived distinction would be an innate misconception, along with the innate notion of any metaphysical “freedom” with regard to the will. But given this innate idea of the autonomous agent, the idea becomes a drive in itself known colloquially as “selfishness” (whether of the “zero sum” variety, or of the “win-win” variety otherwise known as “enlightened self-interest”). This view challenges our idea of altruism, and our notion of “selflessness” is called into question. It would then be conceivable that a variant use of the term “selflessness” might pertain to a state in which this misconception (of the self-as-agent) has become so eroded that it no longer influences the organism’s behaviour.
To recap, there is an innate notion a self-as-agent; more specifically a something that somehow causes the actions of the associated person (or some subset of the actions, given that much of our behaviour is blatantly automatic). But no such object appears as a constituent of the field of experience, and neither does anything that does appear amongst those constituents give any grounds for such a concept. (This is consistent with work initially carried out by Benjamin Libet and supported by a great deal of subsequent work by other investigators.) Some people fear that in relinquishing the metaphysical concept of free will (as it appears in the guise of the agent of action) we are forced into accepting the unpalatable or even abhorrent (as it may seem to them) metaphysical view known as determinism, but this is a misconception. The absence of metaphysical free will does not necessarily entail that the world is unfolding deterministically, since all indications are that there is a level of indeterminism at the atomic and subatomic levels (e.g. the stochastic element introduced when a quantum object undergoes an interaction after a period of non-interaction with any other quantum object). But this caveat is often insufficient to placate such individuals, and their objection might better be considered to pertain to predestination rather than to determinism.
Since it is not at all clear how the stochastic element introduced by quantum systems could possibly give rise to the kind of ordered behaviour that is characteristic of their conception of free will, some people speculate that quantum mechanical indeterminism may leave open a “back door” by which such a self-as-agent might possibly influence the self-as-person. This would be to invoke the notion of a metaphysical subject just as may be done in the case of the self-as-experiencer covered in the preceding section.
4. The Self as the Field of Experience
It seems, then, that the idea of the agent of action and the idea of the subject of consciousness have been accreted onto the concept of the self-as-person, adding nothing useful for the person. The only reasons for retaining these two ideas would seem to be psychological in origin rather than that of conferring any explanatory value. But another idea of self remains to be considered, and this is the idea of self as the entire field of experience. Whereas the idea of self-as-person has pragmatic value for the organism, the idea of self as field of experience has no such value since the idea of the field of experience itself has no pragmatic value. Note that this notion of self is consistent with the idea that consciousness is inessential for all practical purposes, but it cannot be claimed that the idea of self as the field of experience might be grounded in a misconception since the existence of the field of experience is beyond doubt (any such doubt would itself be a constituent of the field of experience). We would simply be giving a short name to the field of experience, albeit a name that invites confusion because of the already extant uses of the word “self”. However, this would be consistent with a certain interpretation of the following passages in Wittgenstein’s Tractatus Logico-Philosophicus:
5.63 I am my world (the microcosm.)
5.631 There is no such thing as the subject that thinks or entertains ideas. […]
5.632 The subject does not belong to the world: rather, it is a limit of the world.
5.641 Thus there really is a sense in which philosophy can talk about the self in a non-psychological way. What brings the self into philosophy is the fact that ‘the world is my world’. The philosophical self is not the human being, not the human body, or the human soul, with which psychology deals, but rather the metaphysical subject, the limit of the world – not a part of it.
Furthermore, this would also be consistent with a certain interpretation of the following passages in Wittgenstein’s Philosophical Investigations:
398: “But when I imagine something, or even actually see objects, I have got something which my neighbour has not.” – I understand you. You want to look about you and say: “At any rate only I have got THIS.” – What are these words for? They serve no purpose. – May one not add: “There is here no question of a ‘seeing’ – and therefore none of a ‘having’ – nor of a subject, nor therefore of ‘I’ either”? Might I not ask: In what sense have you got what you are talking about and saying that only you have got it? Do you possess it? You do not even see it. Must you not really say that no one has got it? And this too is clear: if as a matter of logic you exclude other people’s having something, it loses its sense to say that you have it.
[…] I think we can say: you are talking (if, for example, you are sitting in a room) of the ‘visual room’. The ‘visual room’ is the one that has no owner. I can as little own it as I can walk about it, or look at it, or point to it. Inasmuch as it cannot be any one else’s it is not mine either. In other words, it does not belong to me because I want to use the same form of expression about it as about the material room in which I sit. The description of the latter need not mention an owner, in fact it need not have any owner. But then the visual room cannot have any owner. “For” – one might say – “it has no master, outside or in.” […]
399: One might also say: Surely the owner of the visual room would have to be the same kind of thing as it is; but he is not to be found in it, and there is no outside.
400: The ‘visual room’ seemed like a new discovery, but what its discoverer really found was a new way of speaking, a new comparison; it might even be called a new sensation.
404: […] What does it mean to know who is in pain? It means, for example, to know which man in this room is in pain […]. What am I getting at? At the fact that there is a great variety of criteria for personal ‘identity’. Now which of them determines my saying that ‘I’ am in pain? None.
411: Consider how the following questions can be applied, and how settled:
(1) “Are these books my books?”
(2) “Is this foot my foot?”
(3) “Is this body my body?”
(4) “Is this sensation my sensation?”
(4) Which sensation does one mean by ‘this’ one? That is: how is one using the demonstrative pronoun here? Certainly otherwise than in, say, the first example! Here confusion occurs because one imagines that by directing one’s attention to a sensation one is pointing to it.
Panexperientialism, as it has been presented here, leads to a hierarchical structure of minds exhibiting a three-level ontology consisting of:
the natural world in which distinct objects of experience enter into relation with each other via the conceived “forces of nature”
the all-in-all entailed by the mutual immanence of the objects of experience
the wholeness implied by that mutual immanence
Note that the wholeness would not admit of this division into levels and so must somehow encompass the entirety of this ontological scheme. This raises the question of how the mode of dividedness and the mode of undividedness can be reconciled, but this can only be a problem in the mode of dividedness since the distinction between dividedness and undividedness is itself an aspect of dividedness. Consequently, from the human perspective, this presents a problem that is insurmountable even in principle – i.e. this is a case of recreational metaphysics. But it would be remiss of me to omit the fact that just such an idea of ineffable wholeness is at the core of many of the world’s spiritual systems. Indeed this three-level ontology is strikingly reminiscent of that of Plotinus. Every instantiation of consciousness manifests as a perspective from the centre of the objective world inhabited by its associated object, so panexperientialism would entail a cosmology in which it could be said (paraphrasing Plotinus) that “the centre is everywhere and the outermost boundaries are nowhere”. The entire all-in-all is in constant flux and conceptually divides into distinct processes, some moving in an “upward” or “radially inward” direction (growth) and others in a “downward” or “radially outward” direction (decay), somewhat analogous to convection cells in a heated fluid. Plotinus similarly describes the dynamics of the all-in-all as “procession from the One” and “return to the One”, and he goes on to describe the all-in-all quite strikingly as “boiling with life”. Additionally the idea of just such an all-in-all is the defining feature of the Chinese Huayan school of Buddhism (Japanese Kegon school), which finds its way into Hinduism as the bejewelled “Net of Indra”.
Quoting Wittgenstein, “A picture held us captive” (Philosophical Investigations, 115). This is seemingly the case with regard to the materialist/reductionist picture – a picture into which we are possibly seduced by the success of the scientific enterprise in helping us to conceptually model and understand the objective world. But this picture is not forced upon us by logical necessity, nor by empirical evidence. The upshot is that although many are quick to dismiss panexperientialism, this is an illicit move in the game, especially given that the materialist/reductionist picture exhibits profound problems when pushed to its limits. In physics, the measurement problem, delayed choice histories, nonlocality, and the quantum Zeno effect, all of which present such a challenge for the materialist/reductionist picture, are rendered less enigmatic by panexperientialism. The question arises as to the mechanism by which the consistency of characteristics is ensured across instances of “dissolution” into the wholeness, but by virtue of its very indivisibility the implied wholeness is beyond language and logic.
In this discussion I have presented a positive case for panexperientialism, showing how this view addresses issues upon which the materialist/reductionist picture cannot gain any traction on its own terms.
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Appendix 1: Some Physics
Isaac Newton published his Principia in 1687 and Newtonian mechanics proved more than adequate for well over two centuries. Newton had also speculated that light consisted of a stream of particles, but in 1801 Thomas Young demonstrated that light exhibits interference when passing through two narrow and closely spaced slits, demonstrating that light has a wave-like nature in contrast to the particle-like nature of Newton’s conjecture. In 1814 Pierre-Simon Laplace proposed that a sufficiently powerful intelligence could use Newtonian mechanics to predict all future events from present conditions – a view known as determinism and for which there would be no serious challenges for more than a century. In 1900 Lord Kelvin (William Thomson) identified two outstanding “cloudlets” on the horizon of physics, famously declaring the science of physics to be almost complete. The first of these “cloudlets” was the fact that the Michelson-Morely experiment had failed to find the expected evidence of the “luminiferous aether”. The second was the fact that physical theory failed to correctly predict the profile of the spectrum of light emitted by glowing hot bodies (so-called “black body radiation”) – a problem that later came to be known as the ultraviolet catastrophe. These two “cloudlets” turned out to be in need of far more than just a little “tidying-up”.
In 1905 Albert Einstein published his paper outlining what is now known as the Special Theory of Relativity. This is a theory that subsumes Newtonian mechanics under a new paradigm that extends to velocities approaching that of light, where Newtonian mechanics shows its limitations. With an inspirational change of paradigm concerning the way that velocities add together, Einstein showed that the speed of light is independent of reference-frame (accounting for the first of the two problems identified by Kelvin). A significant consequence of the Special Theory of Relativity is that information cannot be transferred faster than light, and this leads to the conclusion that no two events can be considered simultaneous in any absolute sense of the word – rather any such simultaneity is dependent upon reference frame, or is relative. Hermann Minkowski subsequently contributed to Special Relativity by showing how space and time must be unified in a manner in which they are no longer mutually independent variables, but instead comprise a four-dimensional “space-time” model of the universe.
In 1901 Max Planck made an attempt to explain the profile of the black body emission spectrum (the second of the two problems identified by Kelvin). In a leap of imagination he proposed that radiation is emitted and absorbed in discrete amounts that he called “quanta”, and this seemed to give the correct profile for the emission spectrum. In 1905 Einstein produced a paper on the photoelectric effect in which (despite the fact that Young had shown light to have a wave-like nature) he had to conclude that that light was acting as a stream of particles (later to be called photons). So instead of quantization being a characteristic of the process of emission and absorption as Planck had assumed, Einstein had shown it to be a characteristic of the radiation itself (a conclusion that was resisted until 1923 when Compton’s scattering experiments clinched Einstein’s conclusion). An intriguing aspect was that the description of light as wave or particle was determined by the experimenter’s choice of experimental apparatus: Young’s slits showed light to have wave-like properties and Einstein’s photoelectric effect showed light to have particle-like properties.
The idea of making a measurement upon a classical (i.e. non-quantum) system poses no great conceptual difficulties – we select the attribute to be measured and conduct the measurement – but things are not so simple in the case of quantum systems. It appeared that, whilst between measurements, quantum systems can have attributes that would be mutually incompatible from a classical perspective, analogous to a classical object being (for example) in two places at the same time. This “superposition of states” that quantum systems seem to adopt between measurements imposes constraints upon what can be expected when the next measurement takes place, but not in a manner that makes any sense in classical terms. A new theory was required that subsumes Newtonian mechanics under a new paradigm that extends to the very small, where Newtonian mechanics shows its limitations. This was “quantum mechanics”.
In 1925/26 Erwin Schrodinger presented his famous “wave equation” which mathematically models how a quantum system evolves continuously and deterministically whilst between measurements, but as a superposition of states. The problem remained that whenever a measurement is made upon a quantum system it is always found to be in one and only one of the states that appear in superposition in the Schrodinger equation, and by virtue of the act of measurement it is said to have undergone “state vector reduction”. It seemed, then, that the act of measurement brings about a discontinuous and non-deterministic transition from the superposition described by the wave equation to the actual measured value.
In 1926 Max Born postulated that the Schrodinger wave equation should be interpreted in terms of probability. That is to say that the variable described by the wave equation (given in superposition whilst between measurements) should be interpreted (for each of the states in that superposition) as the probability that that particular state will become the actual state of the system if a measurement were to be made at that time. Born’s postulate admits of two interpretations. Firstly the classical interpretation, that we are constrained to work in terms of probabilities because our knowledge of the system is incomplete. Secondly the non-classical interpretation, that quantum systems differ from classical systems because the probability associated with them is irreducible and ineliminable. The latter interpretation was anathema to some physicists, including Einstein, who held that the conceptual objects with which science deals continue to exist and to have well defined attributes even when not being measured (a form of metaphysical realism). Einstein famously claimed in a letter to Born that “the Old One does not play dice”.
The new “quantum mechanics” was fiercely debated at the fifth Solvay Conference in Copenhagen in 1927, where Nils Bohr rejected Einstein’s realism on the grounds that scientific theories are nothing more than “instruments” that allow us to make more accurate predictions about the world, and tell us nothing about any putative underlying “reality” (a view known as instrumentalism). Furthermore, if different kinds of apparatus give us seemingly incompatible descriptions of a quantum system (e.g. light as both a wave and a particle) then these incompatible descriptions must be considered as complementary and no further interpretation should be placed upon them.
So, consistent with Laplacian determinism, for all practical purposes a classical system may be conceived as completely described by all of its attributes at all times, and any uncertainty in that description would be a consequence of our inability to make sufficiently precise measurements upon one or more of those attributes. However, Werner Heisenberg (initially siding with Bohr on the instrumentalist side of the debate) claimed that it is meaningless to regard quantum systems as having any kind of “reality” at all between interactions. He presented a mathematical argument showing that quantum systems differ significantly from classical systems in that they entail an inherent uncertainty or indeterminism. It turns out that precise measurements upon certain pairs of attributes of a quantum system – e.g. position and momentum – cannot be made simultaneously. A precise measurement of position will leave the momentum indeterminate, and vice versa. This is the “Heisenberg Uncertainty Principle”, which gives a formal footing to the strange aspect of quantum mechanics mentioned above: how the system behaves depends upon what the physicist chooses to measure.
Because of the venue for this conference, the interpretation placed on quantum mechanics by Bohr, Heisenberg, and other physicists that similarly rejected Einstein’s realism eventually became known as the “Copenhagen Interpretation”. In the Copenhagen Interpretation, state reduction became known as the “collapse of the wave function”, and this “collapse” raised the serious question of how to reconcile these two aspects in the evolution of quantum systems – continuous and deterministic whilst between measurements, but discontinuous and probabilistic upon measurements. This is known as the “measurement problem”.
In 1935 Schrodinger (siding with Einstein on the realist side of the debate) proposed a thought-experiment in which he established a link between the quantum world and the classical world in order to demonstrate what he considered to be the absurdity of the Copenhagen Interpretation. Schrodinger envisaged a cat hidden from view in a box in which there is also a vial of poison. The vial is broken upon detection of the decay of a radioactive atom, whereupon the cat would die. The quantum state of the radioactive atom would be in a superposition of two states, both decayed and undecayed, until a measurement took place. Schrodinger’s claim was that, according to the Copenhagen Interpretation, the cat (a classical object) would also be in a superposition of two (classically incompatible) states – both alive and dead – until a measurement took place, and that this was a preposterous suggestion. Schrodinger’s thought-experiment emphasised the need for a more rigorous consideration of the idea of a “measurement” in quantum mechanics.
In 1935 Einstein produced a paper, along with his co-workers Boris Podolski and Nathan Rosen, in which he used an elegant thought-experiment in an attempt to endorse his realist interpretation of quantum mechanics. That thought-experiment is now known as the “EPR paradox” (from the names Einstein, Podolski, and Rosen). The EPR scenario begins with two quantum systems that are prepared such that they exhibit a correlation in respect of a common attribute (the most frequently used example of such an attribute is quantum mechanical spin, though this is not the one used in the original paper). The two quantum systems are then allowed to separate to a distance at which the normal modes of information transfer would introduce a significant delay. When the attribute of interest is measured at one of the systems, the correlated attribute at the other (as-yet unmeasured) system would also immediately be determined (because of the correlation). Now, according to classical theory, any correlation between two events is explained in one of two ways – either one event is the (direct or indirect) cause of the other, or both events are the effects of a common cause. According to the EPR paper the immediate nature of the reduction would eliminate the first of these explanations since this would violate Einstein’s postulate (from Special Relativity) that information cannot be transferred faster than light. This leaves only the “common cause” explanation, and since there were no known variables that could point back to such a common cause, Einstein argued that quantum mechanics was an incomplete account awaiting the discovery of new variables that would complete the account. This became known as the “hidden variables” hypothesis. However, in 1964 John Bell produced a mathematical theorem eliminating the common cause scenario, and this was experimentally confirmed by Alain Aspect in 1977. This seemed to leave the first explanation as the only option, but if this was to be given any credence then faster-than-light influences had to be entertained. In physics parlance any kind of influence that is mediated at or below the speed of light is known as a local influence, and so Bell’s theorem and the Aspect experiment, by eliminating local hidden variables, showed that nonlocal (i.e. faster-than-light) influences must be introduced into quantum mechanics. Indeed realist interpretations of quantum mechanics have been proposed on the basis of nonlocal hidden variables, notably by Louis de Broglie and later, building on de Broglie’s work, by David Bohm, but this avenue remains problematic and is not widely accepted.
In 1966 Cornelis Willem Rietdijk attempted a rigorous proof of determinism that would be consistent with Minkowski’s block-universe model of space-time (in contrast to the indeterminism that had been introduced by the Copenhagen Interpretation of quantum mechanics). This kind of deterministic model would implicate a nonlocal hidden variables theory like that of Bohm. In 2001 Antoine Suarez set up an experiment that made use of the relative nature of simultaneity (as described by Special Relativity) to test for such nonlocal hidden variables. By suitable choice of reference frame in the case of the reduction of an entangled quantum system, the simultaneity of the otherwise immediate reduction can be turned into a sequence “A before B” (permitting A to be the nonlocal cause of B). But by suitable choice of a different reference frame, the same reduction can be turned into the sequence “B before A” (permitting B to be the nonlocal cause of A). Hence Suarez’ experiment is known as the “before-before” experiment. Suarez found that nonlocal correlations persist regardless of reference frame, eliminating the postulate of nonlocal hidden variables and so disconfirming Rietdijk’s proof of determinism. So Bell had eliminated local hidden variables and now Suarez had eliminated nonlocal hidden variables. This presents a problem for realist interpretations of quantum mechanics like that of Bohm. Suarez concluded that “nonlocal correlations have their roots outside of space-time”.
In 1932 John von Neumann, pursuing the Copenhagen Interpretation, showed that there are no formal grounds for locating wave function collapse at any point in the chain of events that begins with the quantum system interaction, moves up through the experimental apparatus, through the nervous system of the observer, and terminates in the observer’s consciousness. This argument permits speculation regarding the extreme ends of this chain, one such extreme leading to the suggestion that “consciousness causes collapse”. The best known expression of this suggestion came in 1967 when Eugene Wigner proposed a variant of the “Schrodinger’s Cat” scenario known as “Wigner’s Friend”. However, the idea that “consciousness causes collapse” has many problems and is difficult to take seriously. The opposite extreme is more enticing, this being the view that wave function collapse takes place upon each and every interaction of the quantum system.
In 1957 Hugh Everett III proposed an interpretation of quantum mechanics that was intended to eliminate the troublesome idea of wave function collapse altogether. He used the idea that any interaction between two systems results in an “entangled” system (as in the EPR scenario), and extended this idea to include the measuring apparatus itself. In this case, then, a measurement results in the quantum system under measurement becoming entangled with the measuring apparatus. This way, the state of the measured system is always relative to the state of the measuring equipment, and vice versa. Instead of a wave function collapse that inexplicably favours a single actual outcome, each measurement generates all of the possible outcomes, with each outcome consisting of an entangled combination of measured system and measuring equipment. The entire ensemble of entangled systems would then exist in a superposition of states, with each individual entanglement continuing on as if in a world of its own. He called this interpretation the “relative state formulation”, but it is better known today as the “many worlds interpretation”. This scenario was not received well at the time of publication, but more recent variations of it have gained popularity amongst a subset of physicists today.
To recap, the Copenhagen Interpretation of quantum mechanics entails a single world in which the superposition of states (given by the Schrodinger wave equation) “collapse” upon measurement to a single state (whatever we may mean by “measurement”) in accordance with irreducible probabilities. This indeterminism yields an “open future” – i.e. a future that does not yet exist – but it says nothing about the past. It would be consistent with the view that only the present exists – a view of time called presentism – and with the view that the past and the present exist but not the future – a view of time called possibilism. However, the demise of absolute simultaneity as described in Special Relativity and in the Minkowski model of space-time results in a block-universe in which the past, present, and future “coexist”, a model that is static and devoid of any privileged “now”. This view of time (or more precisely in this case, of space-time) is called eternalism. The demise of simultaneity entailed by Special Relativity provides strong grounds for pursuing the eternalist view, and this can be made consistent with quantum mechanics by rejecting the single world of the Copenhagen Interpretation in favour of the many worlds of the Everett “relative state” formulation. There is presently no means of testing whether there is a single world (with quantum systems being associated with irreducible probabilities) or, with each measurement on a quantum system, increasingly many worlds, and so subscribing to either one of these positions can only be a matter of prejudice.
In 1978 John Archibald Wheeler conceived a thought-experiment (based on Young’s two-slit experiment) that makes use of the strange fact that the choice of experimental equipment determines whether light exhibits wave-like properties or particle-like properties. The salient point about the two-slit arrangement is that when the detector is of a kind that ignores the paths by which the light reaches it, an interference pattern is observed (indicating a wave-like nature consistent with Young’s version of the experiment), but when the detector is of a kind that takes account of the path (i.e. of which slit the light came through), no such pattern is observed (indicating a particle-like nature consistent with Einstein’s work on the photoelectric effect). Wheeler’s idea was to delay the choice of detector until the light had already passed through (one or both of) the slits. The scenario has since been experimentally tested, finding that the choice of detector still determines whether the light exhibits a wave-like or particle-like nature at the detector. Wheeler commented that “one decides the photon shall have come by one route or by both routes after it has already done its travel” (italics added for emphasis).
In 1954 Alan Turing pointed out a consequence of the statistics describing the decay of unstable quantum systems like radioactive atoms. The probability of finding upon measurement that the state has changed depends on the time interval between measurements, with more frequent measurements reducing the probability of state change. In the limit, where the measurement becomes continuous, the probability of state change reduces to zero – i.e. the state never changes. This effect was experimentally confirmed and given the name “Quantum Zeno Effect” by Sudarshan and Misra in 1977, and is often described using the adage that “a watched pot never boils”.
Appendix 2: Mass in Multi-Particle Systems
In Special Relativity Theory the mass is given by the length of the energy-momentum
4-vector, so in natural units (i.e. taking c = 1):
m2 = E2– p2
Consider two particles traveling in the same direction, taken as the x-axis.
The energy-momentum 4-vectors along the x-axis for the particles are:
p1 = (E, px, 0, 0)
p2 = (E, px, 0, 0)
Each of the particles has an individual mass given by:
m2 = E2– px2
The total energy-momentum of this system (call it system ‘A’) is then:
PA = (2E, 2px, 0, 0)
and since the velocity 4-vector has a squared length of 1 (in natural units),
the total mass of this system (squared) is given by:
mA2 = PA2
= (2E)2– (2px)2
= 4(E2– px2)
or mA = 2m, just as in Newtonian physics.
Now consider a second system (call it system ‘B’) in which the two particles are moving in opposite directions along the x-axis, so we now have:
p1 = (E, px, 0, 0)
p2 = (E, –px, 0, 0)
Once again each particle has an individual mass given by:
m2 = E2– px2
but now the total energy-momentum of this system is:
PB = (2E, 0, 0, 0)
The total mass (squared) for the system is given by:
mB2 = PB2
= 4(E2– px2 + px2)
= 4m2 + 4px2
– i.e. by simply making the particles travel in opposite directions,
the mass of the two-particle system has increased.
When the particles are photons, px2 = E2, so m = 0 and we get:
mA = 0 and
mB = 2px
– i.e. a system of photons has zero mass when the photons are all travelling in the same direction, but non-zero mass when the photons are not all travelling in the same direction.
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1 Many thanks to Dr. John Wykes for presenting this argument.
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