5.4 Philosophy of Mind and Consciousness


By the end of this section you will discover:

How and why the phenomenon of consciousness poses a “hard problem” for physicalists to explain.

What philosophers mean by “qualia” and how this idea is related to the question of consciousness.

How the thought puzzle “Mary’s Room” shows a weakness in the purely scientific understanding of mind and consciousness.


If you are reading this, it seems certain that you have a mind. But what is it? Where is it? How does it work? And, actually, why do you have one in the first place? These are some of the key questions in the philosophy of mind.

Philosophy of mind is a branch of philosophy that studies the nature of the mind and its relationship to the body. The mind-body problem is a key issue in the philosophy of mind, although a number of other issues are addressed, such as the “hard problem of consciousness” and the nature of particular mental states. Philosophers of mind study such things as the nature of mental events, mental functions, mental properties, consciousness, the ontology of the mind, the nature of thought, and the relationship of the mind to the body.

As mentioned in the previous section, there are two primary reasons that many philosophers have not been positive about the prospects for any version of materialism/physicalism, eliminativist or not. One has to do with intentionality, which we have already discussed. But the big one, the one that has kept most physicalists up at night, has to do with consciousness—the most familiar, well-known phenomenon in human life, i.e., our awareness, our experience.

What is the “Hard Problem” of Consciousness?

Contemporary philosophers of mind like David Chalmers, Thomas Negel and Joseph Levine have struggled with the so called “hard” problem of explaining consciousness.  The Internet Encyclopedia of Philosophy summarizes the problem this way:

The hard problem of consciousness is the problem of explaining why any physical state is conscious rather than nonconscious.  It is the problem of explaining why there is “something it is like” for a subject in conscious experience, why conscious mental states “light up” and directly appear to the subject. (IEP, “The Hard Problem of Consciousness,” https://iep.utm.edu/hard-problem-of-conciousness/#SH1b)

According to Chalmers,

What makes the hard problem hard and almost unique is that it goes beyond problems about the performance of functions. To see this, note that even when we have explained the performance of all the cognitive and behavioral functions in the vicinity of experience—perceptual discrimination, categorization, internal access, verbal report—there may still remain a further unanswered question:  Why is the performance of these functions accompanied by experience? (Chalmers, 1995, 202, emphasis in original, op. cit.).

Where Does Your Mind Reside?: Crash Course Philosophy #22

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Contemporary philosopher Henry Shevlin lays out many of the most important issues that consciousness raises for materialism/physicalism very well. In what follows:

What does Shevlin mean by “qualia”?

As I sit writing this sentence, I am enjoying a wealth of experiences. In front of me, the sky is full of the pink and blue hues of approaching sunset dashed with white clouds. Tropical birds chitter in high-pitched trills, while a pair of dogs utter guttural barks at each other. My skin alternately prickles with the last lingering heat of the day, interrupted by the pleasant coolness of an evening breeze.

The scene I have just described is full of experiences with distinctive qualities—colors, sounds, and physical sensations. These qualities of experience are known to philosophers of mind as qualia, an oddly obscure term for an aspect of our lives that could scarcely be more familiar to us. Every waking moment of our lives, we are experiencing various qualia associated with sights, sounds, or feelings. Sometimes, we deliberately seek out new qualia, as when we order an unfamiliar dish at a restaurant, eager to learn what it tastes like. On other occasions, we seek urgently to put an end to some quale (the singular of “qualia”) or another; for example, when we take an aspirin to relieve the throbbing sensation of a headache.

Qualia have been the focus of intense interest in the philosophy of mind and cognitive science for several decades. They possess several apparent features that make them both fascinating and hard to explain. All of these properties are controversial […] but they certainly seem to capture several of the intuitive features of qualia.

What are some of the salient characteristics of qualia?

First, qualia seem to be private: my qualia are a feature of my experience alone, and you can never directly access them. You may have wondered in the past whether other people experience colors in just the same way you do, or whether my blue may be your green. These questions arise precisely because of the apparent privacy of qualia. We can never know which qualia other people are experiencing.

Second (and related), qualia are arguably ineffable; that is, they cannot neatly be put into words. Imagine trying to explain to a person who is blind what red looks like, or (a less extreme example) conveying to a lifelong vegetarian what tuna tastes like. While in both cases, we might attempt to use metaphors (“red is like a trumpet”) to convey the character of the experience, our attempts to do so will inevitably fail to do justice to the relevant sensation.

A final alleged property is that qualia are immediately and fully apprehensible to us just by experiencing them. In this respect, they are distinct from the objects of our experience. Imagine that you are lying in bed at night and you hear a soft thud. You may well wonder what the noise was: a falling object, a door slamming in the wind, or perhaps your housemate returning home. What you don’t have to speculate about, however, is what the noise sounded like to you. This is something you grasped simply by hearing it. More strongly and more controversially, some philosophers have suggested that we can never make errors of judgment about our qualia. If I say that something feels painful to me, for example, then it is nonsensical to suggest I might be in error.  (Shevlin, “Qualia and Raw Fields,” in Hendricks et. al. Introduction to Philosophy: Philosophy of Mind, Ch. 5)

The qualia of our experiences are, in one way, the least mysterious things imaginable. We wake up in the morning and there they are. We go to sleep at night, and they disappear. But as we’ll see, they seem to pose very serious problems for materialism/physicalism. Here is Shevlin again:

In what follows, ask:

Why are qualia hard for science to explain?

One reason qualia have so fascinated philosophers is that they are arguably hard to explain in standard scientific terms. Many of us have probably heard neuroscientists talking about things like synapses, neurons, and different regions of the brain. It is perhaps not too difficult to see how this kind of scientific approach might explain various aspects of our behavior. We might understand perception, for example, in terms of the transmission of information from the sense organs through various processing areas of the brain, or unusual aggression in terms of the release of some hormone or neurotransmitter. It is much harder to see, however, how these kinds of scientific descriptions could ever give us a satisfying explanation of why red looks the specific way that it does, or why cinnamon tastes like this and vanilla tastes like that.

The challenge here is not merely to explain the neuroscience of how vision works or how our tongue relates flavor information to the brain. Important progress is being made every day in understanding questions like these.  Instead, the real difficulty is that while science tells us about how the brain works, it seems unable to tell us what experiences are actually like. To get an idea of the problem, imagine a person who has been completely deaf since birth and wants to know what Beethoven sounds like. Even if we had perfect brain scanners and could show them exactly what happens to someone’s neurons when they listen to music, it does not seem like this could ever properly convey to them the subjective experience of hearing the opening bars of the Choral Symphony.

This creates an apparent challenge for a scientific worldview. If science cannot fully explain qualia, then does it follow that science can only offer us a partial understanding of the universe? More strongly, one might wonder whether the seeming inexplicability of qualia in scientific terms shows that the universe we inhabit does not consist solely of things like atoms, molecules, forces, and other objects from the domain of science, but also contains distinctive, irreducibly mental phenomena (ibid.).

How does the thought experiment “Mary’s Room” illustrate the limitations of the scientific/materialist approach to understanding consciousness?

The challenge is well illustrated by a famous thought experiment called “Mary’s Room” developed by philosopher Frank Jackson (1982) Imagine a woman called Mary who is a brilliant scientist. Specifically, we are told that she knows all the physical facts about color perception: she knows all about the physics of light, the biology of the eye, and the neuroscience of color processing in the brain. However, Mary has never seen color herself, having spent her life in a black-and-white room. One day, Mary leaves her room and sees a shiny red apple for the first time. “Wow!” she thinks, “So that’s what red looks like.”

Mary’s Room attempts to demonstrate that there are certain facts that can’t be accessed by scientific knowledge alone. After all, Mary already knows all the scientific facts about color before she leaves her room. What she lacks, however, is knowledge of the qualia of color; that is, what colors actually look like. She only gains this knowledge when she leaves the room and actually sees colors herself. Hence, the argument runs, there are certain facts that cannot be explained by science, but instead, rely on subjective experience. The argument can be presented formally as follows.

1. Mary knows all the scientific facts about color before she leaves her room.

2. Mary learns new facts (about what colors look like) when she leaves her room.


3. Therefore, not all facts are scientific facts.

Mary’s Room is one of the most famous thought experiments in all of philosophy and has generated a vast number of responses. Most of them challenge premise (2), above, and argue that in fact, Mary doesn’t learn anything new when she leaves her room.

For example, the ability hypothesis claims that what Mary gains is not knowledge but a new set of abilities…. Imagine someone who knows a lot about music but can’t play any instruments. However, after lots of practice, they learn to play the piano. The ability hypothesis suggests that something like this applies to Mary. Prior to leaving her room, she had never seen red objects, so couldn’t recognize a given object as red, or imagine or remember the color red. After leaving the room, her new experiences of red allow her to do all of this. Our sense that she gains knowledge, then, is misplaced—what she gains is a new kind of skill. Some philosophers doubt that this adequately explains away our sense that Mary really does gain a new special kind of knowledge when she leaves her black-and-white room.

How does the “old fact, new knowledge” argument attempt to solve the “Mary’s Room” dilemma?

Another important approach we can term the old fact, new knowledge view. Imagine someone knows that Istanbul was founded in 330AD. They then learn quite separately that Constantinople was founded in 330 AD. Assuming they do not already know that Istanbul and Constantinople are in reality the same city, it seems reasonable to say that the person learned something new when they heard the information about Constantinople. Certainly, they have an item of trivia at their disposal that they didn’t have before. However, since “Constantinople” in fact refers to the same city as “Istanbul,” we should also say that they have not strictly learned any new fact about the universe, having instead encountered a fact she already knew in a different form. Applied to the Mary case, the idea is that Mary really did know all facts about color before she left her room. When she sees red for the first time, she simply encounters these same facts in a new way, namely via her own color vision rather than via the theoretical language of science. One challenge for this view is to offer a developed account of this special experiential way of gaining knowledge while avoiding appealing to any non-scientific or non-physical facts or properties.

Does Mary really “know” all the facts about the color red?

A final approach adopted by some defiant philosophers is to insist that Mary would not gain any kind of new knowledge or ability toward the world when she leaves her room. If she really knew all the scientific facts about color before leaving the room, she would in fact already have all the knowledge and abilities associated with seeing colors, despite never having personally seen them….

This might sound like a flat denial of the powerful intuition motivating the thought experiment. One way to make this approach more persuasive, however, is to focus on the first premise of the argument above, that Mary knows all the relevant scientific facts. Is this really something we can easily imagine?

After all, current science is still incomplete and falls far short of providing us with knowledge of every fact even within its own domain of explanation. Moreover, most scientists are so specialized they know only a small proportion of the facts within their own field. Mary, then, would have [to] be more like a superintelligence from the distant future than a normal human. Given this, should our intuitions about what we can imagine be given much weight?

These responses are only a fraction of the many approaches to Mary’s Room adopted by philosophers. While considerable progress has been made in developing rebuttals to Mary’s Room, it is probably fair to say that there is no one response that has been generally accepted as solving the problem. The puzzle of qualia for the scientific worldview, then, remains a central area of philosophical research.

(Henry Shevlin, “Qualia and Raw Feels,” Ch. 5 of Salazar et.al.)

The Mary’s room thought experiment is one way to motivate the idea that explanations in terms of atoms and void – or of particles and forces, to use more contemporary terminology – simply are not adequate to the task of explaining qualia.

For the rest of this philosophy of mind section of this chapter, we will look in more detail at how philosophers of mind – particularly those of materialist/physicalist leanings – have attempted to answer these challenges and the challenges regarding intentionality that we discussed earlier.

Works Cited

CrashCourse, director. Where Does Your Mind Reside?: Crash Course Philosophy #22. YouTube, YouTube, 1 Aug. 2016, https://youtu.be/3SJROTXnmus. Accessed 12 Apr. 2022.


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PPSC PHI 1011: The Philosopher's Quest by Daniel G. Shaw, Ph.D. is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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