Mysticism and Logic, Chapter VIIIa

Chapter VIIIa, “The Relation of Sense-Data to Physics,” pages 145-164

Russell breaks down Chapter VIII into twelve sections; the chapter is sufficiently involved that my summentary itself will be broken into two posts. This first post (part “a” of Chapter VIII) covers the following sections:

I. The Problem Stated (p. 145)
II. Characteristics of Sense-Data (p. 147)
III. Sensibilia (p. 148)
IV. Sense-Data are Physical (p. 150)
V. ‘Sensibilia’ and ‘Things’ (p. 152)
VI. Constructions versus Inferences (p. 155)
VII. Private Space and the Space of Perspectives (p. 158)
VIII. The Placing of ‘Things’ and ‘Sensibilia’ in Perspective Space (p. 162).

The follow-up post, part b of Chapter VIII, will cover the remaining sections:
IX. The Definition of Matter (p. 164)
X. Time (p. 167)
XI. The Persistence of Things and Matter (p. 169)
XII. Illusions, Hallucinations, and Dreams (p. 173).

Now equipped with that barebones (yet formidable) context, on to the summentary of Chapter VIII…

Physics employs the usual scientific method of experiment and observation. But what we ultimately observe is limited by our senses, and that sense data is not the atoms and molecules themselves. What we think we know about atoms is through suspected correlations with the sense data. But how could such correlations be verified, given that only one side of the correlation, the sense data, will ever be known to us?

We could try to solve the inference problem by postulating some a priori truths: this is the route that philosophy often takes. The postulate-a-truth solution goes beyond experiment and observation, of course, which makes it inadvisable. Alternatively, we could define objects like atoms “as functions of sense-data [p. 146].”

The way we talk about physics is somewhat backwards. We say that when a certain type of wave meets our eyes, that certain colors are perceived. “But the waves are in fact inferred from the colours, not vice versa [p. 146].” So physics goes beyond experimental evidence to the extent that the waves are not themselves defined as functions of the data. From “stuff implies data” we need to move to “data imply stuff.”

We receive multiple sense data at any point, so it isn’t obvious of what a single sense datum consists. For our purposes, we can even accept a complex fact (A is to the left of B), as a sort of sense datum, even though, as opposed to a proper sense datum, the complex fact could be false.

Sense data exist when they are data, but whether the stuff that is sense data persist before or after when they are data is uncertain. “Sense-data at the times when they are data are all that we directly and primitively know of the external world [p. 148].” But there can be more than we know. [We are sort of like flatlanders trying to grasp 3D objects – RBR.] Physics (like metaphysics) in some sense deals with all the particulars, known to us or not. But the physics that we know of needs must deal only with sense data.

“Sensibilia” are the stuff akin to sense data, but without being sensed by any mind. (“Sensibile” is the singular form.) Sensibilia become sense-data by entering into a relationship (of acquaintance with a mind), like men become husbands by entering into a marital relationship. Can we infer (directly unobserved) sensibilia from sense data?

Sense data form “part of the actual subject matter of physics [p. 149].” Even when they are unobserved sensibilia, they are subject matter: observing sensibilia (and hence making them sense-data) adds only awareness to that which is already present.

“Physics” is related to “physical,” and Russell takes “physical” to refer to the stuff that is the subject matter for physics [!?]. A particular is “mental” if it is itself aware of something; facts are “mental” if they involve mental particulars. Russell hopes to show that sense data are physical – they might also be mental, but that is neither here or there for present purposes. [Russell (p. 151) notes that he does not accept the “new realist” position of Mach and James, though Russell’s discussion here is consistent with that position.] Sometimes the questions of the persistence and the physicality of sense data are conflated. Russell will argue that the data are physical – and hence within the scope of physics – though they probably do not persist in an unchanged way.

“Logically a sense-datum is an object, a particular of which the subject is aware [p. 152]” – and the subject is not a part of the sense-datum. The existence and the persistence of sense-data (or proto sense-data) do not require, of necessity, a sensing subject. The subject has sensations, his or her awareness of sense-data, and sensations are mental objects – though sense-data are physical.

We know that a table or other sensibilia appear differently to different people. But can a table (or other sensibile) in the same place simultaneously be both brown (to one observer) and yellow (to another)? Russell cites an article (pdf here) by T. P. Nunn for explaining how this subjectivity does not render sensibilia to be non-physical. Nunn’s solution notes that there are two “places” in question, the place at which the table appears and the place from which the table appears. Each observer’s place at which the table appears is not comparable to that of any other observer – though there can be correlations between these separate spaces. “No place in the private world of one observer is identical with a place in the private world of another observer [p. 154].” A table, then, could be the class of all appearances, or potential appearances, sensibilia, of the object in question. Though the appearances are not identical and cannot exist in the same place at the same time, the table is no less a physical concept – and we don’t need to adopt some ideal realm that contains the actual table.

Mathematical logic has developed the method of replacing a sort of imagined or inferred concept (like irrational numbers) with a constructed concept. Dr. Whitehead is the pioneer, and he suggested the application to physics of this approach to me [Russell]. 

“A complete application of the method which substitutes constructions for inferences would exhibit matter wholly in terms of sense-data, and even, we may add, of the sense-data of a single person, since the sense-data of others cannot be known without some element of inference [p. 157].” But we are far from achieving this ideal. In the meantime, we can discipline those inferences which cannot be avoided: they should be general, explicit, and similar to that stuff whose existence is already given – on this last principle, Kant’s thing-in-itself fails.

Russell permits two inferences: the sense-data of other observers (which uses analogy to accept the existence of other minds, and which rules out building a solipsistic basis for physics); and, the sensibilia that lack a current observer.

No sensibile can be a sense-datum to two observers simultaneously – though their sense-data will be similar, and two people can speak meaningfully of the same table. Everyone has their own private world of sense-data, different from everyone else’s. The place at which a sense-datum exists is a private space. There is no issue, then, with an object having two appearances in the same place, as those appearances exist in separate, observer-specific spaces. Multiple appearances of an object are not an argument against the physicality of the object.

“In addition to the private spaces belonging to the private worlds of different percipients, there is, however, another space, in which one whole private world counts as a point, or at least as a spatial unit [p. 159].” This is the space of perspectives, and its points (individual perspectives) do not require an actual observer to be present making perceptions. Nearby perspectives contain closely correlated sensibilia, and these sensibilia correspond to appearances of one object. Indeed, the object itself can be defined as the class of its appearances.

We can order all the perspectives of a thing in a space by taking similar views – those in which a penny looks perfectly circular, for instance – and arranging them by apparent size. The spatial order we end up with would have been replicated with any object that possessed the same set of appearances (though we could use an ordering metric other than size). “It is this empirical fact which has made it possible to construct the one all-embracing space of physics [p. 161].”

We now have a six-dimensional world: a three-dimensional collection of perspectives, where each perspective is itself three-dimensional. An object has associated with it many lines of perspective, and where they meet is itself a perspective, the one where the object is, the place “at which” it appears. But each perspective also provides its own place “from which” the object appears. Psychology is interested in studying sensibilia in the “from which” place, and physics is interested in studying sensibilia in the “at which” place.

Observers can order the appearances of an object by their proximity (to the mind of the observer, say); “those are nearer which belong to perspectives that are nearer to ‘the place where the thing is [p. 163].’” The fact that, by squinting, the appearance of an object changes, when we tend to suspect that the object itself does not change, is no longer a problem for regarding objects as physical. A thing is a class of appearances. If some appearances change – by squinting, say – then there is some change in the object. But we can define change in an object as occurring only when appearances that become arbitrarily close to the object also change. Squinting results in a change in something, but not in the object perceived.

Mysticism and Logic, Chapter VII

“The Ultimate Constituents of Matter,” pages 125-144

The question “what is matter?” contains an insoluble part and a soluble part, and further, we know how to find the answer to the soluble portion.

The notion that mind and matter are distinct has not been popular with philosophers since the time of Leibniz. Matter itself has been problematized by physicists, and now it looks like a sort of electromagnetic field instead of chunks of palpable stuff. Further, we have learned that the senses through which we encounter matter don’t provide a single, true reckoning: “all our senses are liable to be affected by anything which affects the brain, like alcohol or hasheesh [p. 126].” We cannot trust our senses, including common sense, on the nature of matter.

The commonsensical notions that the stuff we perceive is physical; that it exists outside of our own mind; and, that it persists even when we avert our gaze, are flawed. In particular, the belief in object persistence needs to be re-examined. Following Bergson, objects are like characters in a film: what we perceive in a film to be a persistent person fleeing the police is actually a series of momentary people in close proximity. [Russell says (p. 128) that he heard Bergson’s analogy before he (Russell) had ever seen a movie (“cinematograph”), and that his first trip to the cinema was motivated by a desire to test Bergson’s claim.] So it is with actual men, and tables, and stars. Notice how this view extends to time what we already think about space: an object that “fills” a cubic foot actually consists of many smaller objects in close proximity.

The stuff being arranged in space or time is called [by Russell] “particulars.” The relations among particulars produce the patterns we perceive, the macro objects, which are “logical constructions [p. 129].” Particulars are like individual notes in a symphony – they are ephemeral, but we take notice of their relations. A table is similar, not to a trombone, but to the role of a trombone in a symphony – and is equally amorphous.

When I see a lightning flash, though I experience the flash mentally, through the sense of vision, the flash would still exist in the same way if I were unchanged except that I had lost my mental capacity, and hence could no longer sense the flash. The thing I see is separate from my sight. But people might not accept this claim, in particular, by suggesting that objects (or attributes, like color) cannot really exist outside the mind that notes them.

What does it mean to say that something is “in” the mind? It doesn’t mean that the “thing” is there in a spatial manner (though perhaps “in the brain” does mean that, but physically existing in the brain is not what people intend when they say that a quality like color exists in the mind). Colors are not like beliefs, which seem to be mental, without an external physical manifestation. Though a fire can make us experience pain, the fire itself need not be mental, just because the experience is mediated through our senses and mind.

Those who hold that objects like tables are mental, that they depend upon the observer, mistake the body for the mind. Yes, my perception of an object changes if I squint (or use eyeglasses), but the changes “are to be explained by physiology and optics, not by psychology [p. 134].” The visual representation that I have with eyeglasses disappears when I remove the glasses, but that does not provide evidence that the object itself vanishes. Our visual representations are not “ultimate constituents of matter,” but the whole argument is rendered moot if those ultimate constituents are Bergson-esque, restricted in space and time.

Physics tells us that what we call the sun is 93 million miles away, and that the electromagnetic waves that reach our eyes were emitted from that distance some eight minutes prior to reaching us. But our experience of the sun starts not with the release of the waves, but with the last step, our brain’s coding of the information from the eyes and optic nerve.

Events have the potential to have many different causes, not a single “cause.” One set of causes of “seeing the sun” involves the eyes, nerves, and brain. But we could list other antecedents, not involving these body parts, that possess an equal causal claim. In the case of seeing the sun, we could consider the sun and our eyes and brain as “assemblages of momentary particulars [p. 137]” – that is, the matter that we often take as real is itself a “logical construction,” and the sense data of an observer is the set of particulars caught in the observer’s snapshot or film, as modified by other particulars (such as those corresponding to the observer’s brain). The universe is thus a multiplex: “there are all those [three-dimensional spaces] perceived by observers, and presumably also those which are not perceived, merely because no observer is suitably situated for perceiving them [p. 139].”

This view leads to a six-dimensional space of particulars: the space of a set of particulars (a table, say) is itself three-dimensional, and the positions among sets of particulars can be specified with a further three dimensions.

An observer has a perspective, all that the observer observes, and objects are a correlated set of particulars. One can (often) classify particulars from the perspective viewpoint or the object viewpoint. (Some particulars, like dreams, might not be subject to these dual viewpoints.) Nevertheless, “[w]e cannot define a perspective as all the data of one percipient at one time, because we wish to allow the possibility of perspectives which are not perceived by any one [p. 140].”

Cue time – in “particular,” observer-specific time. The perspective associated with a particular is all the particulars simultaneous with that particular (p. 141). The timeline associated with a particular is its “biography.” As particulars need not be perceived, biographies need not be lived. [Russell calls unlived biographies “official,” in the sense, I believe, of committee membership being ex officio.]

Consider a particular with respect to one perspective. Shift the perspective marginally, and you will get a very similar particular – and this similarity is independent of the rest of the universe. When we think of a specific “thing,” it is the continuity with neighboring perspectives, and the independence from all else, which gives us the class of particulars constituting that “thing.” Physicists generally focus on things when they examine particulars, whereas psychologists focus on the perspective and “biography” associated with one observer.

The view propounded here (concerning the connection between sense-data and the physical world) is not intended to shed light on physics – but it is intended to shed light on standard psychological or metaphysical claims of the mental underpinnings of sense-data. Those standard claims often unduly favor permanence in the constituents of things, and draw on confused views about space and sense-data. Mind is not necessary for the existence of sense data, and “sense-data are merely those among the ultimate constituents of the physical world, of which we happen to be immediately aware; they themselves are purely physical, and all that is mental in connection with them is our awareness of them, which is irrelevant to their nature and to their place in physics [p. 143].”

The theory presented here suggests that there is no conflict between physics and psychology. The ultimate constituents of matter, such that physical things are a series of classes of particulars, means that physics can classify the particulars in one way when discussing matter, and psychologists can classify the particulars in another way (yielding perspectives and biographies).

Is the theory true? It could be, which is more than can be said for most alternative approaches to the question of matter. Further, the theory suggests a starting point from which a tolerable solution eventually can be devised.