Tag Archives: Sense Data

The Data From All the Senses, Part 2 (Lengthy)

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When I refer to “sense data”, I mean information that’s conveyed in one of several ways, either through one of our many senses (of which there are more than the five Aristotle counted), or by whatever other means information makes its way into our stream of consciousness (for example, the introspection that allows us to carry on inner soliloquies). Philosophers sometimes use the term “qualia” to refer to “the introspectively accessible, phenomenal aspects of our mental lives”, but “sense data” emphasizes the informational aspect of our experience. I also think it’s appropriate to think of our conscious experience as a whole. The term “data”, understood as a collective noun, emphasizes what’s often called “the unity of consciousness”.

A term that could be used is in place of “sense data” is “sensorium”. Wikipedia cites the Oxford English Dictionary:

A sensorium is the sum of an organism’s perception … where it experiences and interprets the environments within which it lives…. In medical, psychological, and physiological discourse it has come to refer to the total character of the unique and changing sensory environments perceived by individuals. These include the sensation, perception, and interpretation of information about the world around us by using faculties of the mind such as senses, phenomenal and psychological perception, cognition and intelligence.

As David Chalmers put it in the article I quoted a few days ago: “What unites all of these states is that there is something it is like to be in them. All of them are states of experience.”

So what is sense data? From what is ordinarily called the “mental” point of view, sense data is information expressed as sights, sounds, smells, feelings, thoughts and so on. Although a computer can run a program perfectly well with one source of information (the data stored as tiny magnetic regions on a hard drive, for example), creatures like us need more. We require lots of information about the world in order to survive and it’s beneficial to collect that information in more than one way (echolocation would be especially handy at night). 

Hence, we evolved with various capacities for collecting information about the world inside and outside our bodies. If the information we collect is accurate, it will generally allows us to maneuver successfully and avoid difficulties. If it’s garbled, incomplete, hard to understand, illusory or even hallucinatory, it will tend to be less helpful.

From what is ordinarily called the “physical” perspective, however, sense data is activity in our brains. Scientists, of course, can only detect what’s happening in our brains up to a point, since the technology is so new. We, however, have a front row seat, metaphorically speaking. In fact, we each have a metaphorical theater to ourselves. We each experience some of the activity in our brains as sense data, i.e. sights, sounds, smells, feelings, thoughts and otherwise. Nobody understands how this works yet – how or why particular kinds of activity are experienced in particular ways – but that seems to be only a matter of time.

Among professional philosophers, the idea that sense data or conscious experience is brain activity is controversial, although not so much among scientists who study the brain. The so-called “identity theory” has been debated for decades and various alternatives have been offered. Nevertheless, it still seems to me that mental activity is brain activity, somewhat like heat is the motion of atoms or molecules, a cloud is water vapor and a squirrel is a collection of cells. 

One big objection to the identity theory that seems very wrong is that it leaves no room for minds or mental activity. Many philosophers used to believe that the mind is a mental substance that’s somehow attached to the physical substance of the body (and that made sense if a person’s mind or soul was supposed to float away post mortem). Very few philosophers think that today. Yet there are still those who believe that mental properties are very different from physical properties. Property dualism, in particular, is the idea that consciousness is a fundamental property not reducible to physical properties.

I don’t see any good reason to believe that. The simple, most plausible explanation for why so-called mental events or properties seem different from so-called physical events or properties is this: when we’re conscious, we experience some physical events in our brains as mental events (what I’m calling “sense data”), but we never experience other physical events, either in our bodies or outside them, in the same way. The traditional way of describing this distinction is to say that we have direct experience of what’s happening in our conscious minds and indirect experience (via our eyes and ears, for example) of everything else. 

Consider what we know about perception and feelings like pain or hunger. Stimuli of various kinds come in contact with specialized cells in the body. Electrical impulses make their way via the nervous system to the brain. A tiny number of these impulses are combined with the brain’s own contributions, resulting in conscious experience. It’s the activity in the brain itself that ultimately counts.

You really could be a brain in a vat and have a vivid mental life, assuming the technology existed to allow your brain to receive the necessary stimuli (and thus the necessary information to process) and to react accordingly (by seeking new stimuli, for example, as in “Hey, what’s that noise over there?”). Using the traditional terminology, It’s the end product (the sense data) that you are “directly” aware of. So long as that information kept arriving and your brain could react appropriately, your world would seem the same.

It’s the things that information is about, whether it’s the sunburn on your back, a band playing in the park or your daughter’s first day at school, that we are “indirectly” aware of (again using the standard terminology). But all of it is (or was or will be) physical stuff, whether it’s the band in the park, the electrical stimuli or the brain’s own activity. It’s all ultimately composed of things like quarks and bosons (and maybe some dark matter or dark energy, whatever those are).

But the direct vs. indirect distinction can be misleading in at least two ways. First, calling our awareness of things outside our brains “indirect” suggests that there could be a more direct way of being aware of such things. But how could that possibly be? How could I possibly be more aware of the chair I’m sitting in than by sitting in it, looking at it, measuring it, touching it and so on? Experiencing something outside of us isn’t and cannot be the same as experiencing the brain activity that’s part of us. Nevertheless, using our senses to gain knowledge about such things is the ideal, most direct way there could possibly be.

Second, saying that we are directly aware of sense data may suggest that our awareness is complete. It’s sometimes said that we have “privileged access” to our sense data. That’s certainly true, since nobody else has the same access to our sense data that we do. Similarly, the Stanford Encyclopedia article on sense data lists this as the third defining feature of traditional sense data theories: “Sense data [has] the properties that perceptually appear to us”. That’s usually understood to mean that we can’t be mistaken about what our sense data is. We may interpret our sense data incorrectly, but if you have blue sense data, your sense data is definitely blue, even if the thing your sense data is about (the wall in front of you, for example) isn’t blue at all. It could be a different color, as we usually describe such things. In reality, it’s got no “color” (the blueness you actually see) in itself at all. 

This doesn’t mean that we can always accurately describe what our sense data is or even know what we’re sensing. Data, after all, is sometimes vague, incomplete, too complex to understand and even inconsistent. (Imagine seeing an object directly in front of you that isn’t there when you try to touch it.) It’s reasonable to say that sense data always has the properties that perceptually appear to us, so long as we don’t take that to mean we are always clear about what those properties are.

The most popular objection to sense data theories is that they break the link between us and the external world. If we’re only aware of sense data, how do we know that anything outside our own minds even exists? How do we know that there is a physical world at all? Or perhaps you and I are like Keanu Reeves before he was unplugged.

Given the sense data I’ve had over the years and am still having, I’m very sure that there is a physical world outside my mind that contains New York City, our cat, Rice Krispies and aluminum siding. But am I absolutely, completely, 100% certain beyond any doubt whatsoever? Not really. I could get an extremely, extremely big surprise one day.

But so what? I’m not absolutely, completely, 100% certain that the world wasn’t created 10 seconds ago, with geological strata and historical records in place and all of us enjoying false memories of years gone by. Being able to conceive of a very different world doesn’t make that very different world plausible. Philosophers (some of them) are paid to worry about these things, and many have tried to prove beyond any possible doubt things we and they already know to be true. But the quest for absolute certainty on this or almost any other topic is a waste of time. It’s impossible to achieve and wouldn’t be of any use if it was.

In conclusion, I should mention that, in a 2009 survey of philosophy professors, graduate students and others who follow academic philosophy, only 19% of the respondents accepted or leaned toward “sense-datum theory” or “qualia theory” in the philosophy of perception. However, applying simple labels to philosophical theories is extraordinarily difficult. The most popular answer was “other” with 43%, but coming in second was “representationalism” with 26%. Another article in the Stanford Encyclopedia describes representationalism or representative realism as follows:

… our immediately experienced sense-data, together with the further beliefs that we arrive at on the basis of them, constitute a representation or depiction of an independent realm of material objects — one that we are, according to the representationalist, justified in believing to be true.

I couldn’t (and didn’t) say it better myself.

PS — It’s very difficult to contract Ebola in a country with a decent public health system, so please don’t worry. It’s not spread like a cold or the flu. If you’re in a country with a poor public health system and people are getting the disease, please don’t expose yourself to the bodily fluids of someone who has a high fever, body aches, etc. You can only get it from the bodily fluids of someone who already has symptoms.

The Data From All the Senses

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Alan Lightman, currently Professor of the Practice of the Humanities (!) at MIT, has posted a short article about consciousness at the New Yorker‘s site. Its centerpiece is a visit with Robert Desimone, an MIT neuroscientist who is trying to understand what happens in the brain when we pay attention to something.

Neuroscientists already know that different parts of the brain are activated when we look at faces as opposed to other objects. In one of Desimone’s experiments, people were shown a series of photographs of faces and houses and told to pay attention to either the faces or houses, but not both.

When the subjects were told to concentrate on the faces and to disregard the houses, the neurons in the face location fired in synchrony, like a group of people singing in unison, while the neurons in the house location fired like a group of people singing out of synch, each beginning at a random point in the score. When the subjects concentrated instead on houses, the reverse happened. Furthermore, another part of the brain, called the inferior frontal junction, a marble-size region in the frontal lobe, seemed to conduct the chorus of the synchronized neurons, firing slightly ahead of them.

 Evidently, what we perceive as “paying attention” to something originates, at the cellular level, in the synchronized firing of a group of neurons, whose rhythmic electrical activity rises above the background chatter of the vast neuronal crowd. Or, as Desimone once put it, “This synchronized chanting allows the relevant information to be ‘heard’ more efficiently by other brain regions.”

Something else that’s interesting in the article is what the neuroscientist says about what’s been called philosophy’s “hard problem”, i.e. understanding the nature of consciousness: 

Without hesitation, Desimone replied that the mystery of consciousness was overrated. “As we learn more about the detailed mechanisms in the brain, the question of ‘What is consciousness?’ will fade away into irrelevancy and abstraction,” he said. As Desimone sees it, consciousness is just a vague word for the mental experience of attending, which we are slowly dissecting in terms of the electrical and chemical activity of individual neurons.

DeSimone compares understanding consciousness to understanding “the nature of motion” as it applies to a car. Once we understand how a car operates, there’s nothing more to say about its motion. Or in a physiological comparison he might have made, we will eventually understand what consciousness is or how it works just like we now understand what digestion is or how it works.

But I think there’s something importantly different about consciousness as compared to the motion of a car or even the digestion of a sandwich.This is how David Chalmers, the philosopher who first referred to the “hard” problem (as opposed to the “easy” problems) of consciousness, put it in his 1995 article “Facing Up to the Problem of Consciousness”:

Consciousness poses the most baffling problems in the science of the mind. There is nothing that we know more intimately than conscious experience, but there is nothing that is harder to explain. All sorts of mental phenomena have yielded to scientific investigation in recent years, but consciousness has stubbornly resisted….

The really hard problem of consciousness is the problem of experience. When we think and perceive, there is a whir of information-processing, but there is also a subjective aspect…. This subjective aspect is experience. When we see, for example, we experience visual sensations: the felt quality of redness, the experience of dark and light, the quality of depth in a visual field. Other experiences go along with perception in different modalities: the sound of a clarinet, the smell of mothballs. Then there are bodily sensations, from pains to orgasms; mental images that are conjured up internally; the felt quality of emotion, and the experience of a stream of conscious thought. What unites all of these states is that there is something it is like to be in them. All of them are states of experience.

It is undeniable that some organisms are subjects of experience. But the question of how it is that these systems are subjects of experience is perplexing. Why is it that when our cognitive systems engage in visual and auditory information-processing, we have visual or auditory experience: the quality of deep blue, the sensation of middle C? How can we explain why there is something it is like to entertain a mental image, or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? 

So Desimone claims that once we understand the physical processes that occur in the brain (the mechanisms of consciousness), the philosophical problem of consciousness will evaporate. Chalmers, on the other hand, says that even if we were to understand the “physical processing” in the brain, the hard problem of consciousness would remain. According to Chalmers, “specifying a mechanism that performs the function” of consciousness, as Desimone hopes to do one day, won’t solve the mystery at all.

I agree with Desimone up to a point. I think the neuroscientists will eventually answer the philosophers’ question as Chalmers posed it in the paragraphs above. Why should such and such physical processing give rise to an inner life? Well, why should such and such physical processing give rise to digestion or respiration or, for that matter, to water boiling or leaves falling? When such and such physical, chemical or biological events take place, what happens is digestion, respiration, water boiling and leaves falling, as the case may be. If an organism’s parts are arranged a certain way, the organism will have an inner life. Or if, as might be the case one day, a machine’s parts are arranged a certain way, the machine will have an inner life. That’s how the world – the world we happen to be in – works (or will work).

I don’t believe this “why should” question concerning experience or consciousness is very interesting from a philosophical perspective. It seems to me that it’s “merely” a very difficult scientific question to which scientists haven’t yet found the answer. It certainly isn’t the hardest problem in philosophy.

To me, a more interesting question is this: What is felt experience anyway? What exactly is the deep blue or middle C that we experience? For example, when we look at an orange, the precise nature of our experience depends on several factors, including the surface of the orange, the light in our environment and our sensory apparatus. That’s why it makes no sense to say that the surface of an orange is orange in itself. When we hold an orange, the surface feels bumpy, but it presumably wouldn’t feel the same way if we were much, much smaller or much, much larger.

I’m not suggesting at all that David Chalmers has failed to recognize the real issue here. But I think that stating the issue in this way emphasizes the most puzzling aspect of consciousness. Here’s another way of putting it: if the world outside of us isn’t just as we experience it, and it’s not in our heads either (there are relatively few colors or sounds inside our brains), where the hell is it? 

These days, philosophers often compare brains to computers. The brain is the hardware and the mind is the software. But it occurred to me recently that software doesn’t do anything unless it has data to process (that’s not a great insight if you’ve ever worked with or thought about computers). This got me to wondering if we should think of our experience as data. Not the kind of data that computers process, but a special kind of data that takes a variety of forms (in Chalmers’ words, “the felt quality of redness, the experience of dark and light, the quality of depth in a visual field….the sound of a clarinet, the smell of mothballs…. bodily sensations…. mental images…. the felt quality of emotion…. a stream of conscious thought”). We might call this kind of data “sense data”. 

But, lo and behold, that’s exactly what a number of philosophers in the early 20th century, including Bertrand Russell and G. E. Moore, began calling it. (Actually, I already knew that, but it was still a pleasant surprise when I realized I’d gone from thinking about computers to thinking about a 100-year old theory).

Theories that refer to sense data and similar entities aren’t as popular among philosophers as they used to be, but such theories have been one of the most discussed topics in epistemology (the theory of knowledge) and the philosophy of perception for a long time. William James referred to “the data from all the senses” before Russell and Moore (although James wouldn’t have accepted Russell’s or Moore’s particular views). And sense data theories had their precursors in the 17th and 18th century writings of Rene Descartes and the British empiricists Locke, Berkeley and Hume. 

As usual, the Stanford Encyclopedia of Philosophy has a helpful article on the subject. The author, Michael Huemer, characterizes sense data in this way (using “data” in the traditional plural sense rather than as a singular collective noun):

On the most common conception, sense data (singular: “sense datum”) have three defining characteristics:

  1. Sense data are the kind of thing we are directly aware of in perception,
  2. Sense data are dependent on the mind, and
  3. Sense data have the properties that perceptually appear to us.

Many philosophers deny that sense data exists or that we’re directly aware of it. Proposition 3 above is also especially controversial. It’s also often argued that if we were actually aware of sense data, we’d be cut off from the world around us. I don’t plan to discuss any of this further right now, but it’s a topic I want to get back to. It’s a really hard philosophical problem.

PS — There is a funny site called Philosopher Shaming that features anonymous and not so anonymous pictures of philosophically-inclined people owning up to their deepest and darkest philosophical secrets. I uploaded my picture two years ago: 

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Perception: A Representative Theory by Frank Jackson

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Frank Jackson is a well-known philosopher from Australia. Perception, first published in 1977, is an argument for a Representative theory of visual perception similar to John Locke’s. Jackson sums up the book in the last paragraph:

The first four chapters present my case for a Sense-datum theory of perception. Chapter 5 gives the reason for holding that all sense-data are mental. This forces a choice between Idealism and Representationalism. In chapter 6, I argue that there is no good reason for not choosing Representationalism. And, finally, in [the last] chapter, I have, first, attempted to justify my taking the perception of things as basic throughout; and, secondly, I have tried to make more precise … the particular kind of Representationalism that should be chosen.

The Sense-Data theory of perception has had a long history in philosophy. Its principal tenet is that we never perceive physical objects directly. Instead, what we immediately perceive are mental objects called “sense-data”. Thus, when I see the wall in front of me, I immediately perceive a mind-dependent blue expanse, a sense-datum (or set of sense-data), not the wall itself. In Jackson’s words, a visual sense-datum is “something seen, but not in virtue of [seeing] anything else”. Physical objects, on the other hand, are seen, but always by virtue of seeing something else, namely, sense-data. Furthermore, there is a kind of causal relationship between physical objects and the sense-data that “belong to” those objects. That’s why sense-data are said to “represent” the external world.

I’ve read that Jackson no longer endorses the theory he presents here, but Perception still provides a good account of one version of the Sense-Data theory. Professor Jackson makes many interesting distinctions and responds to a number of criticisms. One criticism he anticipates is that he is spending too much time analyzing the language of perception (Chapter 2, for example, is called “Three Uses of ‘Looks'”). He responds that his analysis of language isn’t meant to show whether sense-data actually exist. Instead, it’s meant to help us decide whether believing in the existence of sense-data (accepting the theory) is a reasonable thing to do and how the theory should be stated.

I read Perception because I’ve been thinking about the topic a lot lately and think the Sense-Data theory is probably the best one (even though it’s probably considered a bit old-fashioned now; for one thing, philosophers talk about “qualia” these days instead of sense-data). It’s common for philosophers to think of the mind as software running on the hardware of the brain. But if we’re going to think of our minds/brains as computers running programs, it makes sense to think of the input to these computers as data. Just as a computer program processes data and not the real stuff in the world, we process data as well. In our case, colors, sounds, smells, and so on, are different kinds of data. It just so happens that the data we process isn’t made up of numbers or ASCII characters (or electronic on/off settings); our perceptual data is made up of red or blue expanses, soft or loud noises and pleasant or unpleasant aromas. We don’t perceive the world “directly”, because that can’t be done. We perceive sense-data that represent the world; in similar fashion, computers process electronic values that represent the world too.