Chalmers on the Explanatory, Conceivability & Knowledge Arguments

The Explanatory Argument

David Chalmers says that the “easy problems” of consciousness explain “only structure and function”. They don't explain consciousness. Therefore “no physical account can explain consciousness”.

The Conceivability Argument

We can conceive of a physical system that is note-for-note identical to us but which doesn't have consciousness. (Though what has the psychological notion of conceivability got to do with the problem of consciousness?)

Such as system would therefore be a zombie. Alternatively, it may be a zombie-invert in that some of its experiences are inversions of those of human beings.

The invert-zombie has the same nuts and bolts as us; though nevertheless it has different experiences. So the inverted zombie is still allowed his experiences.

There is also the conceivability of a partial zombie who also has experiences; though not as many as those of human beings – perhaps he can only feel pain.

The point is that all these zombies are physically identical to us from the third-person point of view and their behaviour will also be indistinguishable.

What about their first-person point of view? What is it like to be a zombie of whatever kind? Well, there's nothing it is like to be a bona fide zombie!

On a larger scale. What about a physically identical universe that doesn't, however, give rise to consciousness; though which does give rise to zombies? We can say that such zombies are indeed "naturally possible". However, according to our laws of nature, they probably couldn't exist. That is, given identical physical and bodily facts, then such a universe couldn't help but give rise to consciousness. (This is what some non-reductive physicalists and supervenience theorists believe.)

Let’s take this further.

There could be an identical universe that didn't give birth to consciousness. If this were the case, then consciousness must be something above and beyond the physical if such a counterfactual scenario were possible. In addition, if we can conceive of such zombies in our world or at other worlds, then Chalmers claims that it is "metaphysically possible" that there could be zombies.

What does metaphysical possibility add to the notion of conceivability?Chalmers codifies and simplifies this with a logical argument:

i) It is conceivable that P & not-Q.
ii) If it is conceivable that P & not-Q, then it is metaphysically possible that P and not-Q.
iii) If it is metaphysically possible that P & not-Q, then materialism is false.
iv) So materialism is false.

(Can a mere possibility make materialism false?)

Again, we can see Chalmers’ slide from conceivability to metaphysical possibility. Why should it be that simply because we can conceive of something then that something is metaphysically possible? This has an almost empiricist ring to it in that all conceivables (or ‘ideas’) must come from somewhere or entail metaphysical possibility.

Can we conceive a round square? No. Then it isn't metaphysically possible. Can we imagine a man with five legs? Yes. Then it's metaphysically possible.

The Knowledge Argument

To put the case simply. We could never, and have never, deduced or inferred consciousness from the sum of all physical facts. Though, then again, the same can be said about water. We could study H2 O until the cows come home; though we would never deduce (or infer) the reality of water - its wetness and drinkability - from such physical facts. We can only do so a posteriori – in this case, through science, which tells us that water is indeed H2 O. Though no scientist has ever (or could ever) infer or deduce water’s wetness, etc. a priori. (Or could they? Is water’s transparency an emergent property?)

Does Mary lack knowledge about red? She obviously lacks the experience of red. Is the experience of red a ‘fact’? What sort of fact would it be? Frank Jackson argues that if she finally came to actually experience red, she would learn a ‘new fact’ about red which must be over and above her knowledge of its physical basis and even beyond her powers of deduction from such facts. That is, experience emerges from the physical; though it can't be read off from the physical. That is the essence of emergentism.

Jackson concludes that Mary does indeed know all the physical facts; though not all the facts. There must be non-physical facts (one of which is consciousness).

The strong conclusion to all this is that

i) If there are more than physical facts

ii) and that these things can't be deduced from physical facts

iii) then materialism must be false.

That's because materialism only allows physical facts in its world-picture.

The Shape of the Arguments

Chalmers then attempts to codify and simplify the arguments in strictly logical terms.

Firstly we can think in terms of epistemic entailment, deducibility, explicability and conceivability.

Let us take epistemic entailment.

This is a priori entailment or implication in that it doesn't depend on (further) experience. If we have

P ⊃ Q

we have a material conditional from the physical facts to an arbitrary phenomenal fact. When we know that P is the case, then we must also know that Q is the case without further experience.

In the case of consciousness, P doesn't entail or imply Q a priori. We can't deduce Q from P. Similarly, we can conceive of P without thereby also conceiving of Q. Or, in functional terms, if P is functional, then we can't deduce Q from P because consciousness “is not a functional concept” (as we saw earlier in this debate).

These logical uses of the material conditional can also be applied to the conceivability argument, the knowledge argument and the explanatory argument.

Taken one by one.

If we can conceive of zombies, then zombies are metaphysically possible. If we can't deduce consciousness from all the physical facts, then some facts - those of consciousness - aren't physical. If physical explanations aren't adequate, then there must be non-physical facts that require non-physical explanations.

Now we can talk of another kind of entailment: ontological necessitation.

We can say that P necessitates Q. In the material conditional P ⊃ Q, we can say that P can't hold without necessitating Q. It is ontologically necessary that P necessitates or entails Q. Again, if this were the case, then materialism would be false.

The other interesting point about these arguments is the movement from an epistemic gap to an ontological gap. More precisely, we can argue that:

1. There is an epistemic gap between physical and phenomenal truths.
2. If there is an epistemic gap between physical and phenomenal truths, then there is an ontological gap, and materialism is false.
3. Materialism is false.

The obvious point to make here is the slide from the epistemic gap to an ontological gap. What does that mean?

If we can't slide from our knowledge of P to Q, then that must be because P and Q are ontologically different. If P and Q were ontologically of the same order, then we could move, epistemically, from P to Q.

Why does a lack of epistemic movement from P to Q entail ontological difference? Couldn’t that epistemic gap be accounted for simply in terms of our epistemic limitations or our inadequate knowledge or physical devices? We at one time couldn't move from H2 O to the wetness of water. That epistemic or scientific gap didn’t engender an ontological difference between H2 0 and water or even water’s wetness. Does a lack of knowledge about X entail the fact that X is ontologically weird or irreducible?

David Chalmers on the Hard & Soft Problems of Consciousness

 

David Chalmers makes the helpful distinction between the ‘hard’ and ‘soft’ problems of consciousness.

The soft problem includes the ability to discriminate stimuli, or to report information, or to monitor internal states, or to control behaviour. Prima facie, you can see that these problems can be accounted for in third-person or scientific terms. For example, someone can tell us how they discriminate stimuli with his verbal reports. All this can also be explained neurobiologically. The same goes for the reports of information that we can achieve or carry out. (The problematic ‘easy problem’ is the monitoring of internal states which, prima facie, doesn't seem scientifically kosher.)

 

The ‘hard problem’ is the problem of experience. There is something it is like to experience this, that or the other. What does that mean? It means that we are phenomenally conscious of this, that or the other. Mental states also have their own feel, as it were. When we are having a mental state (if we do indeed have distinct mental states), there is something it is like to be in that state.

What are conscious states in the first place? They include states of perceptual experience, bodily sensation, mental imagery, emotional experience, occurrent thought, etc. There is something it is like to perceive a red apple. There is something it is like to feel a toothache. There is something it is like to imagine Tony Blair. There is something it is like to feel depressed about something. There is even something it is like to make an arithmetical calculation. Of course we will now need to explain what exactly we mean by saying that ‘there is something it is like to…’ and why this makes consciousness ‘unique’ and something non-reducible to the physical.

Chalmers is more precise about this phrase ‘what it is like’. He introduces explanatory technical terms to do so.

For example, conscious states have a phenomenal character with phenomenal properties that characterise what it is like to be in that state.

What, then, are phenomenal properties? The conscious state of perceiving a red apple has phenomenal properties. The properties include the experience of the colour red or the feel of the apple. A toothache can be ‘nagging’ and other pains can be sharp or blunt. The mental image of Tony Blair will have certain phenomenal properties, such as the redness of his face or the emotional responses to the image. Similarly, depressions may be painful or tiring and may engender other phenomenal properties such as lethargy or anger. And even an arithmetical cognition can be accompanied by certain emotions such as that of excitement or tedium.

Chalmers then asks a fundamentally different and equally important question about consciousness.

“How and why do physical processes give rise to experience?”

Intuitively, consciousness, experience or mentality doesn't seem physical at all. How is my mental image of Tony Blair in any way physical? Is my sensation of the red of a red apple in any way physical? And so on. The relation between the physical and the mental is problematic because we can imagine that all the physical processes and events could happen without giving rise to any conscious experience. Such functions and processes “could occur in the dark”. Chalmers calls this problem the “central mystery of consciousness”.

Let's get back to the ‘easy problems’.

What are the easy problems and why are they easy?

These problems are about certain behavioural or cognitive functions. If we lift one leg and are conscious of lifting one leg this can be explained in neurological and neurophysiological terms. As for cognitive functions, these too can be explained in neurological terms, or at least in principle they could be. More explicitly, we can talk in terms of the causal role of a function in a cognitive system and how such causal roles, within the brain, cause us to lift one leg or make a logical inference from p to q. The function takes on the form of a causal role in the production of behaviour and we need only see what exactly the mechanisms within the brain and body are that carry out such causal roles.

In terms of the brain, Chalmers states that such mechanisms are neural or computational in nature (why computational?). As for examples of these functions or causal roles, we can site discrimination, integration, access, report and control. We can intellectually distinguish a cow from a horse. We can integrate new knowledge with old knowledge. We can access our memory system or even past mental images. We can report internal states and past perceptions. We can control our behaviour through cognition as when we build a house. Though, alas, why are any of these mental functions accompanied by experience?

And so we have ventured on to the hard problem of consciousness.

What is the relation between these physical functions in the brain and experience? Such a relation would need to abide by ‘natural principles’ if it is to stand the test of materialism or physicalism. What is it about physical processes that bring about states of consciousness? Why do they do so in the first place?

Bertrand Russell’s Theory of Types

Theory of Types 1

Bertrand Russell’s theory of types seems quite commonsensical at a prima facie level.

That is, different objects, or their many types, can't be treated in the same way within any philosophical or logical system. In Russell’s case, the important thing is that the predicates applicable to different types of objects will differ depending on the type under scrutiny. More specifically, these predicates will be true or false of particular objects depending on the type of object that is predicated.

In Russell’s scheme, objects are arranged in some kind of hierarchy from objects of the least generality to objects of the most extreme generality. In terms of statements, this means that if predicates change according to their types of objects, then statements will likewise change in according to the type of objects they are statements about. So the statements we make about individuals or particulars can't be made about classes. Similarly, the statements we make about classes can't be made about classes of classes. And so on into indefiniteness.

What of different types of individuals? Is this theory true of these types too?Clearly, this theory has relevance to the class of all classes that do not belong to themselves. According to Russell, the theory of types is intended to prevent the paradox discovered in the said class of classes. It was said these classes both are and aren't members of themselves. The original assertion was about classes, not classes of classes. That is, it is said of classes that they either are or aren't members of themselves. This part doesn't result in paradox.

For example, the class of abstract entities is itself an abstract entity. Therefore it's a member of itself. On the other hand, the class of pink shoes is not a pink shoe. Therefore it's not a member of itself. So such classes don't generate any paradoxes.

We introduced another class that is a class of classes. It was, therefore, of a higher logical order than first-order classes. We talked of the class of all classes that aren't members of themselves. This class generated a paradox: it is both a member of itself and not a member of itself. This is the paradox that Russell attempted to solve or prevent. How did he attempt it?

He created his theory of types. And, according to this theory, the predicates and statements we apply to objects depend on the nature of the type of objects being talked about. Clearly, a class of classes is not of the same logical order than a basic class; just as basic classes are of a different logical order than individuals.

We've said that classes can either be members of themselves or not members of themselves. That’s fine. However, we also asked whether or not a class of classes, the class of classes that aren't members of themselves, is a member of itself. It was concluded that it both is and isn't a member of itself. This, of course, is paradoxical. So how does Russell’s theory prevent this paradox from occurring?

Again, different objects have different predicates and statements made about them. A class is a different ‘object’ than a class of classes. It follows that we can't predicate or assert about this class of classes the same kind of things we predicate and assert about first-order classes. We said that the predicate ‘a member of itself’ is either true or false of the classes that either are members of themselves or not. However, our main concern is a class of classes: the class of all classes that aren't members of themselves. So we can't ask of this class the question whether or not it's a member of itself because that kind of question can only be made of classes, not classes of classes. And if these questions can't be asked in the first place, then this class of classes is not in fact paradoxical after all.

A.J. Ayer writes that it is “nonsensical” to even ask if the class of all classes that aren't members of themselves is itself a member or not a member of itself. This question can only be asked of first-order classes, not of second-order classes or classes of classes.

                                                   The Theory of Types 2

It's not only classes, predicates and expressions that differ depending on the objects they're applied to: the theory also applies to ‘numerical expressions’. These expressions, according to Russell and/or Ayer, change their ‘sense’ depending on whether or not they count individuals, classes or classes of classes.

This is an interesting use of the term ‘sense’ if we bear in mind Frege’s notion of sense and reference and all the later theories about reference. Usually proper names, for example, are not supposed to have a sense. So it seems strange, prima facie, that the theory of types claims that numerical expressions have different senses depending on what they are applied to.

However, it may not be numbers themselves that have different senses; but the expressions in which they are constituents. It also seems strange that the way we ‘count’ different types of objects will also be different, regardless of the ‘senses’ of the numbers within the expressions. Again, perhaps I need to know what is meant by ‘numerical expressions’ and whether such expressions have constituents that somehow are relevant to the notion of ‘sense’.

There is a problem with the theory of types. In traditional class theory, the same object can belong to different classes. Though in the theory of types, we must be careful to treat different objects in different ways. This may result in certain classes becoming smaller than they originally were because many classes contain different types of objects as members. This will result in both a proliferation of classes, and also the numerical shrinkage of the classes that are deemed to already exist.

Though, according to set-theory, we define the natural numbers by reference to classes. That is, the class of all two-membered classes is in fact the class we call the number 1. So if class membership, the number of members, defines the natural numbers, then the shrinkage of classes that results from the theory of types may result in their being classes that aren't large enough - in terms of members - to define the higher natural numbers. That is, the higher numbers may not be able to correspond with any classes because there aren't enough classes with correlative higher memberships. The classes needed to account for the higher numbers may simply run out. The may not be enough classes with higher enough memberships to account for the higher natural numbers.

Another way of putting the theory of types - in this class-membership and numbers sense - is that the conditions that allow objects to belong to certain classes becomes more stringent. Classes become better defined, as it were. And if the conditions of class membership are more stringent, then clearly many previous classes will effectively become smaller in terms of their numbers of members. And, again, if this is the case, then certain higher numbers may not find their correlative classes in set-theory. This is clearly a problem for set-theory and the theory of types. Rather than reject a set-theoretic account of numbers, many logicians in Russell’s day and after simply rejected his theory of types. Other theories, of course, were created and adopted after the period in which Russell formulated his theory of types.

D.H. Mellor on Ontological Pluralism

Rather than adopt a position of monism or dualism when it comes to properties, D.H. Mellor adopts what he calls a ‘pluralist’ approach to properties.

It would be strange that in this huge universe of ours, and amongst its infinite properties or objects, that there were only two kinds of entities – mental and physical. Indeed I would more likely go for one kind of entity or property rather than the rather-too-neat postulation of two. Or, as with Hugh Mellor, go for a plurality of properties or objects.

This multiplicity or plurality of kinds of objects or properties seems to go against the scientific search for simplicity and the metaphysical desire for ontological parsimony. However, we can't reject the possibility of a plurality of different properties simply because it will complexify our scientific and philosophical endeavours. Perhaps the world simply is complex and it's complex because it's made up of a plurality of different objects or properties.

Of course scientists will happily accept the fact that there “is a great plurality of properties” (109). It's just what we conclude from this scientific acceptance of a prima facie plurality.

For instance, does this mean that a distinct property can't be reduced to another distinct property? Are these properties basically irreducible? If they aren't, then are they genuinely distinct at all?

Take Mellor’s own list of properties: electrical, gravitational, chemical, biological, psychological. Many philosophers will argue that the psychological is indeed reducible to the biological; though also to the chemical, electrical and even the gravitational.

The biological is essentially made up of the chemical; though it isn't strictly reducible to the chemical (for many reasons). Perhaps the chemical can be (fully?) reduced to the electrical and even the gravitational.

Mellor himself says that “there is no fundamental distinction of kind amongst them” (109). Rather, there “are lots of little distinctions, and interesting questions about which are reducible to which” (109). What Mellor is saying here doesn't make what he says any different to what the average scientist says and not even to the scientific reductionist. So how does this play on his ontological ‘pluralism’ at all?

Scientists are reductionists who also accept that “there is no fundamental distinction of kind amongst them” (109). They will also say that there are (only) “lots of little distinctions” to be made about them. Mellor even accepts reduction when it comes to (some of) these properties. What does his ontological pluralism amount to and how is it different to ontological monism and ontological dualism?

Mellor accepts that it may be possible to reduce “a lot of sciences... in some non-trivial sense to one basic science” (109); though he also says that this is “not a very fundamental one” (109). He then stresses what it is that all the sciences share and how it is they differ.

For a start, all the natural sciences “are involved with phenomena” (109). These phenomena “can be physical, chemical, biological, psychological, or whatever” (109). Not only that: these different phenomena “are all studied in ways that are methodologically similar” (109). However, all these disciplines will “differ in detail according to their subject-matter” (109). So if there are differences, these differences will be brought about by the different subject-matters of the natural sciences. Despite that, their methodologies will be 'similar' regardless of the differences ‘in detail’. As in the case of Mellor’s ontological pluralism, he says little that is controversial or even interesting here.

D.H. Mellor or Parapsychology

Hugh Mellor offers a very interesting criticism of parapsychology. It's similar to Karl Popper’s view that ‘pseudo-sciences’ - such as Freudianism and Marxism - make it the case that they can't be falsified. Parapsychology goes a step further than this. Its failure to prove something counts “as a kind of success” (110). Mellor writes:

“What’s wrong with parapsychologists is that they count failure as a kind of success; that is, they think that failure to understand a phenomenon bestows a kind of glamour upon it, makes it something special, a paraphenomenon. It does nothing of the sort: all it means is that there’s something we still don’t understand.” (110)

Of course this “failure to understand a phenomenon” - and the concomitant bestowing of “a kind of glamour upon it” - is something that can be applied to what people believe about UFOs, extra-terrestrials, astral travelling, ley lines, ‘the stars’ and all the rest. One gets the feeling that a lot of true believers in this stuff wouldn't even like their darling subjects to be proved by science – that would take away the glamour and the mystique (which is at the heart of all these subjects and pursuits).

Of course it's also the case that, as with Marxism and Freudianism, claims about UFOs, extra-terrestrials, astrology, and the like are also unfalsifiable in principle because the believers in such stuff always rely on some ‘auxiliary hypothesis’ to counteract any evidence that works against what it is they believe. (For example, non-believers never see UFOs because they are brainwashed by the CIA or extra-terrestrials keep well away from all sceptics.)

Should the Philosophy of Mind be Constrained by Science?

It's often said that the philosophy of mind "should be constrained by science".

However, much philosophy has always been constrained by science - at least to some degree. Straight after Thales, for example, Aristotle was both a philosopher and a scientist. 

It's also been the other way around. Newton was imbued with the Platonism and the Aristotelianism his age reacted against. And many early-20th-century physicists (such as Mach, Poincaré and Einstein) were either Berkeleyan idealists or some kind of Kantian.

So the relation between science and philosophy has always been a reciprocal one.

Of course there are many philosophers around today who believe that because the mind and consciousness are so unlike the things which physicists or chemists study, that the philosophy of science must be an a priori pursuit – even an a priori science!

Although it's often said that science can’t tell a blind person what a colour looks like, an alien what a sponge feels like, or any human “what it’s like to be a bat”, there are still very many aspects of the mind that can be known by science. So perhaps the best thing to do is not to highlight the no-go areas of mind. Similarly, not to tell philosophers what are the acceptable areas of the study of mind.

As already hinted at, it can be said that science can't give us any information about "phenomenal consciousness" – or "what it is like" to smell a rose or listen to Mozart. Scientists, of whatever discipline, could tell us which neurophysical factors and features are causally responsible for all things phenomenal. They could/do even tell us which parts of the brain "subserve" mental events and consciousness generally. Though, some philosophers may argue, none of this has anything directly to do with the mind.

For example, a scientist may as well tell us that every time I form a mental image of the Cheshire Cat the light is on in my bedroom. Thus he could reduce my introspective image of such an image to the physical basis of the electric light and how that light impinges on my sensory receptors, then enters the nervous system… and, eventually, ends with a mental image of a Cheshire Cat. Even if it were the case than an electric light subserves - or were the "material substrate" of - my mental image, no neuroscientist could tell me anything about my mental image itself. Again, all they could do is tell us the physical substrate of such mental events or states - their "subveniance-bases". They could tell us no more than this.

However, it may still be the case that although science doesn't tell us what it's like to smell some horse manure or form a mental image of a cat, there are still many scientific factors which are relevant to these aspects of the philosophy of mind. And if not in these precise examples, then surely in other cases.

The question is:

What can science tell us about the mind?

Or:

Can science tell us anything about the mind?

Decades ago it became clear to many that we can't reduce the mind to the brain (as with the Identity Theory, etc.). It even became probable that no strict correlations between mental states (or events) and the brain could be found.

Other philosophers (such as Donald Davidson - with his "anomalous monism") argued that there are no mind-to-brain (or "psychophysical") laws; or, for that matter, brain-to-mind scientific laws. Not only that: there are no mental laws per se.

As for being constrained by science. This normative possibility doesn't make much prima facie sense. Philosophy has often been ahead of science. (And, indeed, vice versa.) So why should we constrain the non-empirical and non-experimental speculations of philosophy when so often in the past philosophy has shown science where it should go next? In addition, philosophers have also shown us which aspects of science have shown little logical or conceptual sophistication.

Though, of course, science simpliciter is itself speculative in nature. And scientific hypotheses have pushed science forward. So even if the philosophy of mind is still "aprioristic" (which, in most cases, it isn’t), then there would still be no good reason to place constraints on the philosophy of mind (or on any area of philosophy for that matter).

Neuroscience has told us many things about the brain. And cognitive science has also told us many things about the mind itself. Both areas have told us things about mental illness, "blind sight", the nature of colour vision, our cognitive faculties and which component parts of the brain subserve them, and so on. The science of psychology can also tell us about mental illness. 

Here again psychologists don't need to know much about the neurochemical nature of the brain to empirically observe the behaviour of the mentally ill. Blind sight, at least in some cases, can be shown to be the result of brain damage or cognitive failures in the synaptic regions of the neurons. Colour vision is well studied by physiology and neuroscience. 

However, and again, many philosophers still say that scientists can't tell us what the colour blue looks like or what it's like to suffer the pain of diarrhea.