Binding is the process of tying various features of a visual scene such as colour, shape, edges, and contours, features detected in various places in the visual cortex, together into an experience of a unified, three-dimensional object. Binding may be necessary for consciousness of individual objects but it does not seem to be sufficient. We must, it seems, also be jointly conscious of the various elements to have unified consciousness of an object.
Next, unified consciousness of contents. In unified consciousness of contents, if an experience that one is having provides consciousness of any object or content, then it provides consciousness of other objects or contents and of at least some of the items as a group. We speak of experiences rather than representations in deference to those who doubt that we experience in representations, or need do so: Kant distinguishes between the kind of acts of synthesis needed to attain consciousness of individual objects and the kind of acts of synthesis needed to attain consciousness of a number of objects at the same time as a single array of objects experienced by a single subject Brook He builds his argument for necessary causal connectedness on the latter.
Unified consciousness of contents appears to be central to our kind of consciousness. If consciousness of these two items were not unified, an important, indeed probably the most important, way of comparing them would not be available. One could not answer questions such as, Is the car the same colour as the WordPerfect icon?
That is what unified consciousness does for us: Since relating item to item in this and related ways is fundamental to our kind of cognition, unified consciousness is fundamental to our kind of cognition. As we will see in Section 4. These disorders leave people with a massive cognitive impairment. Most theorists outside of philosophy and many within accept that there is a second form of conscious unity related to unified consciousness of contents, namely, unified consciousness of acts of experiencing.
It is present when, for the current acts of experiencing that one is doing, consciousness of one act of experiencing consciousness of how one is experiencing something, for example seeing it, imagining it, … provides consciousness of other acts of experiencing. This explication is structured to be neutral as to whether unified conscious states include a multiplicity of conscious states.
Not all theorists accept that this second form of unified consciousness exists. Those who promote the so-called transparency thesis, the claim that we are not directly conscious of our own experiencings, deny that we have any such form of consciousness Dretske ; Tye Tye, for example, says that when we hear something, we are not conscious of the auditory experience, just what it represents.
Many theorists have also had a fourth thing in mind when they speak of the unity of consciousness, namely, unified consciousness of oneself , the thing that has the experiences. Here, one is or certainly seems to be see the discussion of Rosenthal in Section 3. Mutatis mutandis , the same holds for the single common agent of various bits of deliberation and action. One has unified consciousness of self when one is conscious of oneself as the single common subject of experiences of many items in many acts of experiencing. The unified consciousness here seems not to be a matter of joint consciousness.
Indeed, if Kant is right, when one is conscious of oneself as subject, one need not be conscious of oneself as an object at all A, A, B However, something similar might be at work. One seems to be conscious of one and the same thing as one and the same thing, namely, oneself, via a number of acts of experiencing. Generalizing the latter notion, it has been claimed that reference to self does not proceed by way of attribution of properties or features to oneself at all Brook If so, one would not be conscious of oneself as one kind of thing rather than another.
We might call it unity of focal attention. It differs from the other forms of unified consciousness that we have delineated. In the others, consciousness ranges over either many experienced items unified consciousness of contents , experiencings of many objects unified consciousness of experiencing , or multiple acts of access to oneself as subject of many experiencings unified consciousness of self. Wilhelm Wundt captured what we have in mind in his distinction between the field of consciousness Blickfeld and the focus of consciousness Blickpunkt ; Wundt  The consciousness of a single item on which one is focussing is unified because one is conscious of many aspects of the item in one state or act of consciousness especially relational aspects, e.
In unified focal attention, one integrates a number of cognitive abilities and applies them to an object. Note that, if there are forms of unified consciousness different from focal attention, then, contrary to Posner and others, attention is not a component of all forms of consciousness Hardcastle All five of the forms of phenomenal unity can, to one degree or another, be attributed to Kant. The first four are clearly Kantian but there is a connection to him even with respect to the fifth. See, for example, Bn. Since Hume  Whether they do exist is the topic of Section 3. We will close this section by noting that the forms of unified consciousness distinguished above are not the only kinds of mental unity.
Earlier we mentioned Gestalt unity. There is also unity in the exercise of our cognitive capacities, unity that consists of integration of motivating factors, perceptions, beliefs, etc. Human beings bring a strikingly wide range of factors to bear on a cognitive task such as seeking to characterize something or trying to reach a decision about what to do about something. For example, we can bring to bear: Not only can we bring all these elements to bear, we can integrate them in a way that is highly structured and ingeniously appropriate to our goals and the situation s before us.
This form of mental unity could appropriately be called unity of cognition. It is plausible to hold that unity of cognition is required for unity of focal attention. However, there is at least some measure of unified cognition in many situations of which we are not conscious, as is attested by our ability to balance, control our posture, maneuver around obstacles while our consciousness is entirely absorbed with something else, and so on. At the other end of the cognitive process, we find an equally interesting form of unity, what we might call unity of behaviour: The precision and complexity of the behavioural coordination we can achieve would be difficult to exaggerate.
Think of a concert pianist performing a complicated work. However, this capacity to unify behaviour, though doubtless a product of unified consciousness, does not figure in what unified consciousness is. Now that we know what we are talking about when we talk about unified consciousness, the next question to ask is: Does consciousness have the properties that it would need to have to be unified? If this division of questions looks peculiar, notice that it can apply to Santa Claus, too. We can develop an account of what Santa Claus would be like without committing ourselves on the question of whether such a being exists.
However, the division may look peculiar in another way: How could anyone deny that consciousness is unified? That it is seems just obvious. In fact, there has been a good deal of skepticism on the matter. Some will urge that before we ask whether unified consciousness exists, we should first ask, Does consciousness exist?
Even those who hold that the long-standing idea that intentionality see entry is a matter of attitudes to propositions is false and ripe for elimination, Paul and Patricia Churchland for example, allow that consciousness exists, though they urge that the concept be trimmed a bit see, for example, Patricia Churchland Some writers have taken Dennett to deny that consciousness exists, either directly or by implication. He himself has said repeatedly that consciousness is real, however A few writers, Wilkes and Rey for example, have espoused true eliminativist about consciousness but they are a tiny minority.
Many philosophers have been sceptical about whether consciousness is unified. It is possible to be sceptical about whether all consciousness is unified, whether as many conscious states are unified as we might think, and, the strongest form of scepticism here, whether there is any unity of consciousness. Let us examine the three in reverse order. Among recent writers, perhaps the most sceptical about consciousness being unified is Rosenthal. Why merely a sense? Mental states are conscious, when they are, in virtue of their being accompanied by HOTs [higher-order thoughts] and each HOT represents its target as belonging to the individual who also thinks the HOT in question.
Across a range of such self-ascriptions, one develops a sense of being their common subject. However, this sense could be wrong. The experiences thus ascribed, says Rosenthal, could be supported by or located in a diversity of subjects. It is because of this possibility that Rosenthal asserts that all we have is a sense of consciousness being unified. Even when theorists such as Hume and Rosenthal deny that consciousness is unified, sometimes unity of some sort still seems to be at work in their models. Now, this consciousness of oneself is not consciousness of any old object, it is consciousness of oneself, oneself as the bearer of conscious states.
If so, Rosenthal allows that one kind of unified consciousness exists despite himself. The point these people make is not just that the mind works mostly out of the sight and often out of the control of consciousness. Virtually everyone agrees on that and the point would in no way tell against there being a real unity of some kind in the part that does enter consciousness. Rather, they maintain that not even all conscious states are unified with other conscious states. Note that the claim here is not just that we are conscious of less of the contents of our mind than we think, as Freud and the psychoanalytic tradition argue.
The claim is that our consciousness of even many states of which we are conscious is not, or not fully, unified. That we act against what we clearly know to be our own most desired course of action or do things while telling ourselves that we must avoid doing them are advanced as reasons for holding the view but these are not obvious examples of lack of unity. A change blindness experiment might offer a more substantial example.
The Unity of Consciousness
In this experiment, a subject sits in front of a computer screen wearing an eye tracker visor. There is a paragraph of text on the screen. The subject is asked to read the text. However, everything around the word or phrase at fixation, everything above, below and on both sides, beyond about 5 degrees of arc is chaotic: What is remarkable about this experiment is that, while to observers all appears chaotic except for a succession of words or phrases—they are marching to a different saccadic drummer—the subject has no consciousness that anything in the paragraph is ever out of the ordinary.
If the subject is one of those people who automatically reads any text in front of her, often she has no idea that the experiment has even started! What this experiment shows, Dennett Yet subjects are conscious of the rest of the screen in some ways. They are aware of movement, for example. If so, this experiment would be an example of conscious states that are not fully taken up into unified consciousness. We would have unified consciousness of fewer of our conscious states than has been thought. Note that the argument just examined is not an argument that unified consciousness does not exist.
Even if we have conscious states that are not unified or fully unified in consciousness, the most that that could force us to do would be to shrink the range of states over which consciousness is unified or fully unified. Indeed, those who hold that the extent to which consciousness is unified has been overstated owe us an account of what has been overstated.
When theorists claim that a some conscious states are not in unified consciousness, we should ask: Not unified with what? One plausible answer would be: The unified conscious mind. Here is one way to view the matter. Once upon a time, some theorists held that all conscious states are unified and indeed that all mental states are conscious. As we saw, Brentano is an example.
We will return to this view in the next Section. The main difference between this pre-twentieth century vision of unified consciousness as ranging over everything in the mind and view we just examined is that on the latter view, less of consciousness is unified than the earlier view held. Dennett is interesting in this regard. As we saw, he can plausibly be read as rejecting the traditional picture of unified consciousness. Yet he can still invoke unity. Nothing, I submit … What is it like to be a brace of oxen? Why is the answer nothing? To sum up the discussion of scepticism about unified consciousness so far, the argument that the unity of consciousness is real, indeed is a central feature of our kind of mind, seems to be strong.
That said, there are theorists who maintain not only that some conscious states in a subject are unified but that all conscious states must be unified. Bayne and Chalmers As we saw, Brentano probably held this view. Hill does, too. Scepticism about this view would be weaker than either of the two kinds of scepticism about unified consciousness that we just examined. It is difficult or impossible to imagine a subject having two phenomenal states simultaneously, without there being a conjoint phenomenology for both states.
Merely having phenomenal states might seem too little but Bayne and Chalmers are talking about phenomenal states where, for them, to have the state is for the state to be like something.
If we recast to make this element explicit, we get a claim of some real intuitive appeal: Interestingly, Kant seems to have believed something similar: A and B having conjoint phenomenology is exactly what unity consists in, according to Bayne and Chalmers. Put this way, the unity thesis has some real appeal. Are there reasons to be sceptical of the unity thesis, presumptive counter-examples say? Spelled out as we have spelled it out, we do not know of any. Bayne and Chalmers consider brain bisection cases to be putative counter-examples because, on some concepts of the subject of experience, we can think of there still being one subject in these cases even though not all the conscious states are unified.
There are at least three ways to respond. The simplest is just to deny that there is one subject, at least for the period of the split. A second would be to note that, however one counts subjects during the period of the split, there is evidence that many conscious experiences in that body are not like anything to some subject. If so, the apparent lack of conjoint consciousness of them will not be a problem.
We will discuss the third response in more detail in Section 4. The unity thesis is a very strong thesis. Theorists could hold both that consciousness is unified and that this unity is important and yet deny that the unity thesis is true. One of the most interesting ways to study psychological phenomena is to see what happens when they take an abnormal form or break down.
Phenomena that look simple and seamless when functioning smoothly often reveal all sorts of structure when they begin to malfunction. What can we learn from these cases? As a rough grouping tool, we will treat unified consciousness as breaking down in ways that fit a two-by-two matrix. The cases we will consider can be grouped according to whether unified consciousness appears to continue but in an unusual form, one instance of it splitting into two for example, and situations in which it appears to deteriorate more severely, to the point where it may even be said to have been destroyed.
And we will find examples of both kinds that occur at a time and across time. Indeed, some of the disorders that we will examine are both at a time and across time. At a time, situations of disorder in which unified consciousness is retained may take a number of forms. There are cases where consciousness seems to split within one brain and body. The much discussed commissurotomies brain bisection operations are the best known example. Across time, the closest analogue may be dissociative identity disorder, about which more shortly. There may be cases in which a single occurrence of unified consciousness spans two bodies; some have said this about some mirror twins.
And there are cases in which the array of phenomena over which unified consciousness ranges becomes strangely circumscribed: We will describe all these phenomena in more detail below. What is interesting for our purposes is that in all these kinds of cases, those in which unified conscious seems to split, those if any in which it seems to span two bodies, and those in which its range seems to shrink, the unity itself seem to be intact. It has not been destroyed or even damaged.
It is just housed in an unusual way. The cases just introduced contrast with situations in which we have just one instance of consciousness of some kind ranging over the usual phenomena or some of them, but where the unity, to dramatize a bit, appears to have shattered, not split or expanded or shrunk. In these cases, the unity of consciousness is not just unusually housed.
It has been seriously compromised. No medical procedure to do with consciousness has received as much philosophical attention in recent times as commissurotomies, more commonly known as brain bisection operations. Nagel was perhaps the first philosopher to write on them; his paper continues to be influential. Since then, Puccetti , , Marks , Hirsch , Lockwood , Hurley , Bayne , , Schechter and many, many other philosophers have written on these operations.
Indeed, the strange results of these operations in certain controlled conditions was one of the things that brought the unity of consciousness back onto the cognitive research agenda. In these operations, the corpus callosum is cut. The corpus callosum is a large strand of about ,, neurons running from one hemisphere to the other. When present, it is the chief channel of communication between the hemispheres. These operations, done mainly in the s but recently reintroduced in a somewhat modified form, are a last-ditch effort to control certain kinds of severe epilepsy by stopping the spread of seizures from one lobe of the cerebral cortex to the other.
For details, see Sperry , Zaidel et al. In normal life, patients show little effect of the operation. In particular, their consciousness of their world and themselves appears to remain as unified as it was prior to the operation. How this can be has puzzled a lot of people Hurley The original unity seems to be gone and two centres of unified consciousness seem to have replaced it, each associated with one of the two cerebral hemispheres.
Here are a couple of examples of the kinds of behaviour that prompt that assessment. The human retina is split vertically in such a way that the left half of each retina is primarily hooked up to the left hemisphere of the brain and the right half of each retina is primarily hooked up to the right hemisphere of the brain. Now suppose that we flash the word TAXABLE on a screen in front of a brain bisected patient in such a way that the letters TAX hit the left side of the retina, the letters ABLE the right side, and we put measures in place to ensure that the information hitting each half of the retina goes only to one lobe and is not fed to the other.
If such a patient is asked what word is being shown, the mouth, controlled usually by the left hemisphere, will say TAX while the hand controlled by the hemisphere that does not control the mouth usually the left hand and the right hemisphere will write ABLE. Or, if the hemisphere that controls a hand usually the left hand but not speech is asked to do arithmetic in a way that does not penetrate to the hemisphere that controls speech and the hands are shielded from the eyes, the mouth will insist that it is not doing arithmetic, has not even thought of arithmetic today, and so on—while the appropriate hand is busily doing arithmetic!
Recently, this standard assessment has been challenged. In his important book and other publications, Tim Bayne suggests that there are not two centres of consciousness. There is just one. What explains the appearance of duality is that this single centre of consciousness switches in the material of which it is consciousness from one hemisphere to the other. He calls this the switch model To so much as get this approach off the ground, it is crucial that that there be little or no evidence of a centre of consciousness that is conscious of, say, A , B , and C but not D , E , and F and at the same time of a centre of consciousness that is conscious of D , E , and F but not A , B , C.
What we just called the standard assessment starts from a belief that there is lots of such evidence. Because brain bisection operations have attracted so much attention outside of psychiatry and neurology, we have included references to some of the more important writings. We will not do so for the rest of the disorders we will introduce.
For fuller accounts and references, consult a general textbook of psychiatry. Here we are interested in them only for the vicissitudes of unified consciousness that they display, or might be thought to display. In addition to cases in which one body may have two centres of unified consciousness, there are cases in which one centre of unified consciousness may span two bodies. Mirror twins sometimes have such an appearance.
Mirror twins are biologically identical twins where each body mirrors the other. Brain bisection cases are putative examples of the number of centres of consciousness not lining up with the number of brains and bodies from one direction. Mirror twins might be an example from the opposite direction.
In connection with unified consciousness, this possibility is interesting. The best-known case is the case of Greta and Freda Chaplin, who came to light in the U. Two bodies were involved but the bodies acted in ways that would have been compatible, at least, with a single instance of unified consciousness spanning them. Each body could finish complicated and unpredictable sentences started by the other.
The two did everything they could together. When separated by more than a few metres, they complained bitterly, each body reporting that it felt like a part of itself was being ripped out. No professional discussion of the case has been found, unfortunately, but it was widely reported in the press at the time, for example in Time , Apr. Whatever is going on in hemi-neglect, unified consciousness seems to remain. It encompasses an experience of only half the body or half of objects seen, not of the whole body or whole objects. So hemi-neglect is another phenomenon in which there may be a major change in the phenomena over which unified consciousness without unified consciousness itself being degraded.
Another phenomena in which unified consciousness seems to remain but with a bizarrely circumscribed range is anosognosia. In this condition, a person who has suffered loss of function often as a result of a stroke is unaware of the deficits Gennaro a. Thus, a person now blind will insist that she can see—and will stumble about in a room bumping into things.
A person whose limbs are now paralysed will insist that his limbs are moving—and will become furious when family and caregivers say that they are not. Everything about this phenomenon is controversial, including whether there is any real multiplicity of consciousness at all Hacking ; Dennett a. DID can take two forms. When one is active, the other s usually is are not.
This form of DID is called the co-conscious form in the literature but the term names something very different here from what James, Parfit and the like had in mind when they used the term. In fact, sometimes the dissociation in both forms of DID is behaviourally as complete as it is in brain bisection patients in the lab. In some particularly severe forms of schizophrenia, the victim seems to lose the ability to have an integrated, interrelated experience of his or her world and self altogether. The person is unable to put together perceptions, beliefs and motives into even simple plans of action or act on such plans if formed, even plans to obtain sustenance, tend to bodily needs, escape painful irritants, and so on.
Here, it is plausible to suggest that the unity of consciousness has shattered rather than split. The behaviour of these people seems to express what we might call mere experience-fragments, the contents of which are so narrow and unintegrated that the subject is unable to cope with daily life and interact with others in the ways that, for example, split brain subjects can. In schizophrenia of the severe sort just described, the shattering of consciousness is part of a general breakdown or deformation of mental functioning: In another kind of case, the normal unity of consciousness seems to be just as absent but there does not seem to be the same sort of general cognitive or affective disturbance.
This is true of what some researchers call dysexecutive syndrome Dawson, What indicates breakdown in the unity of consciousness is that these subjects are unable to consider two things together, even things directly related to one another. For example, such people cannot figure out whether a piece of a puzzle fits into a certain place even when the piece and the puzzle are both clearly visible and the piece obviously fits. They cannot crack an egg into a pan. Trevarthen reports a similar syndrome in a few patients. In the cases he reports, commissurotomy patients are conscious of some object seen in the right side of the visual field by the left hemisphere controlled so that the information is received by only that hemisphere until an intention is formed to reach for it with the left hand, controlled by the right hemisphere.
Somehow the intention to reach for it seems to obliterate consciousness of it in the hemisphere that controls speech, presumably the left hemisphere. However, if the object is slid over to the left visual field, then the speech-controlling hemisphere reports that it can see the object again—even though the object can now be seen only by the right hemisphere and the left still controls speech! Unlike commissurotomy cases, it is not the case that a conscious experience of the second item exists within another unified consciousness. If there is any experience of the second item at all, it is not conscious.
Rather than consciousness being split into two discrete parcels, there is just one diminished parcel. The rest of the conscious experiencing that is typical of normal consciousness has disappeared. Some hold that the deficits are not in unified consciousness at all; they are in the capacity to process perceptual information.
On this view, consciousness remains unified but patients can no longer can take in what is happening. Here we will explore only the idea that the problem is with unified consciousness. If it is even possible that this is where the problem is, we can learn interesting things about the unify of consciousness.
Many of the disorders that we have considered are fairly directly a result of changes to the brain. Cognitive neuroscience is the study of the relationship between the two.
The best-known objects of such study in connection with unified consciousness are brain bisection operations commissurotomies. Can a single structure account for what is going on in all these phenomena? The Kantian taxonomy of forms of unified consciousness considered in Section 2. As we said earlier, one natural way to think of the conditions just sketched is to break them into two groups. In one group, however drastic the change in unified consciousness, unified consciousness remains in a largely complete form.
Arguably, this group would include brain bisection cases, hemi-neglect, anosognosia, and DID. In the second group, schizophrenia of the severe kind we sketched, dysexecutive disorder, and simultagnosia, it is more natural to think that unified consciousness has been damaged or even destroyed. Brain bisection cases first. On the standard way of conceptualizing these cases, the key evidence for a duality of some kind is that there appear to be situations in which whatever is conscious of some items being experienced in the body in question is not conscious of other items being experienced in that same body at the same time.
We looked at two examples of the phenomenon in Section 4. With respect to these experienced items, there is a significant and systematically extendable situation in which to be conscious of some of these items is not to be conscious of others of them in a single unified consciousness where we would expect such consciousness. If so, brain bisection patients fail to meet the conditions for unified consciousness of contents.
This seems to be what motivates the judgment that these patients have two centres of consciousness. Let us describe the case a bit more precisely. But nothing in the patient would be conscious that both items are being seen on the basis of seeing them. Indeed, the apparent split runs still deeper. Between the two hemispheres there seems to be a split in unified consciousness of experiencing , too: Consciousness of doing some experiencing goes with lack of consciousness of doing other experiencing that is going on in the same body. There seems to be a split in unified consciousness of self , too: Consciousness of oneself as subject on the basis of doing acts of experiencing in that body goes with lack of consciousness of oneself as subject on the basis of other acts of experiencing being done in that body.
If so, for many conscious states in these patients, there two instances of joint consciousness section 2. To be sure, this assessment is not universally accepted. As we saw, Bayne and Chalmers and Bayne Because there may be no duality of unified consciousness at any given time. Rather, a single instance of unified consciousness may be switching back and forth between the material in the two hemispheres.
As Schechter has urged, evidence of a simultaneous duality of consciousness would be a major problem for this approach. We will not attempt to assess the relevant evidence here see Brook for further discussion. Even if Bayne is right, that should not affect the prospects of a unified account of disorders of unified consciousness—what is going on in brain bisection cases would not be a disorder of unified consciousness! Next, dissociative identity disorder DID. We will take up hemi-neglect and anosognosia shortly. In cases of DID, a central feature is either some pattern of reciprocal amnesia or a strong sense that another is inside and yet still separate.
This again seems to be a situation in which being conscious of some experienced objects by having the experience goes with not being conscious of others in the same body in the same way. The main difference is that the breach seems to be at a time in brain bisection cases, but can be either across time or at a time in DID cases.
If so, the breakdown in unity will again consist in breakdowns of joint consciousness. Now the second group. This distinction seems to shed some interesting light on the three phenomena. The evidence suggests that the first kind of synthesis continues to be available to dysexecutive and simultagnosia patients: The damage seems to be with respect to the second kind, being conscious of multiple objects in a single act of consciousness.
These people seem to achieve some measure of unified focal attention with respect to individual objects but unified consciousness of multiple objects is either restricted or missing. With the severe forms of schizophrenia that we sketched, patients may lack even the ability to perform the first kind of synthesis. In a different jargon, these people may lack even the capacity for object constancy.
On this analysis, hemi-neglect and anosognosia are a bit different from the other conditions. Here there is no apparent breach of joint consciousness. Neither a split nor a breakdown in unified consciousness is evident. Rather, in both conditions, there appears to be a shrinking of the array of phenomena over which otherwise intact joint consciousness can range. To sum up, it appears that there is some prospect of placing all the conditions we have considered within a single structure of Kantian distinctions, first between unified consciousness of contents and unified consciousness of experiencing, then between conscious experience of individual objects and unified conscious experience of multiple objects.
Thought insertion might pose a problem for this scheme. The deficit is in something to do with thinking of these thoughts as unified with the rest of conscious life. Normally, we think of ourselves as the subject and agent of all our experiences. In thought insertion, the victim does not appear to himself to be either subject or agent of some of the experiences of which he is in fact the subject and agent Mylopoulos Unified consciousness at a given time synchronic unity has mainly been our topic so far.
We now turn, more briefly, to unified consciousness over time diachronic unity. As was noted as long ago as Kant, unity across time is required even for such rudimentary mental operations as counting A ; indeed, unity across time is crucial for virtually all cognition of any complexity. Now, unification in consciousness might not be the only way to unite earlier cognitive states earlier thoughts, earlier experiences with current ones but it is certainly a central way and the one best known to us.
In its synchronic form, we have suggested that a natural way to think of unified consciousness is in terms of joint consciousness. Diachronically, unified consciousness has an additional feature; it requires retention over time, specifically, retention of earlier experienced contents as one experienced them.
What the retention crucial to diachronic unity consists in is a matter of some interest. It is tempting to assume that it is a kind of memory. However, as Husserl already told us, there is reason to be sceptical of this approach.
There is a difference between experiencing a succession from time 1 to time 2 and merely remembering experiencing what happened at time 1 while experiencing something at time 2. Kelly raises a similar question. Suppose that one is listening to a melody. It has five notes and the final note is just being played. If one simply recollected the earlier notes, one should experience a chord, not five notes spread out and related to one another in time. Whatever this process is like, it is clearly vital to our kind of unified consciousness.
Without it, one could not hear any sequence as a sequence or so much as read a simple sentence. Though some theorists call this across-time process unity of consciousness, a more distinctive name for it would be the continuity of consciousness. Even a seemingly simple, current experience is in fact a continuous experience of more than one instant, and must be if one is to hear a sound or perceive as opposed to remember any temporally stretched phenomenon.
How can one have a unified conscious experience not just a memory of duration? Here again the debate that we mentioned earlier over whether a unified conscious experience is one experience or an assembly of many experiences rears its head. Whatever may be true of the kind of diachronic unity we just discussed, the kind of diachronic unity associated with personal identity is clearly a kind of memory, specifically, a kind of autobiographical memory.
At least since Locke, philosophers have argued that as far back as unified consciousness via the right kind of autobiographical memory extends, there extends the person, one and the same person over all this time. The right kind of autobiographical memory is memory of the having, feeling, or doing of earlier experiences, emotions, actions, and so on.
We must be careful here. There is lots of autobiographical memory that is not memory from the point of view of experiencing. Some important philosophers have urged that memory-carried diachronic unity is not sufficient for being one person over time. Kant, for example, argued for a dissociation here, in his famous critique of the third paralogism.
If so, diachronic unity is not sufficient for personal identity Brook Locke and Kant may be less far apart than this brief discussion would suggest. We are merely using them to illustrate the two positions, not discussing either of them fully. Phenomena relevant to identity in things other than persons can be a matter of degree. This is well illustrated by the famous ship of Theseus. Suppose that over the years, a certain ship was rebuilt, board by board, until every bit of it has been replaced. Is the ship at the end of the process the ship that started the process?
Now suppose that we take all those rotten, replaced boards and reassemble them into a ship. Is this ship the original ship? It seems that there is no determinate answer to these questions. As such case studies show, things can come apart in experience that seem inseparably unified or singular from our normal first-person point of view Sacks , Shallice , Farah Or to pick another example, third-person data can make us aware of how our experiences of acting and our experiences of event-timing affect each other in ways that we could never discern through mere introspection Libet , Wegner Nor are the facts gathered by these third person methods merely about the causes or bases of consciousness; they often concern the very structure of phenomenal consciousness itself.
First-person, third-person and perhaps even second-person Varela interactive methods will all be needed to collect the requisite evidence. Using all these sources of data, we will hopefully be able to construct detailed descriptive models of the various sorts of consciousness. Though the specific features of most importance may vary among the different types, our overall descriptive project will need to address at least the following seven general aspects of consciousness sections 4.
The relevant sort of qualitative character is not restricted to sensory states, but is typically taken to be present as an aspect of experiential states in general, such as experienced thoughts or desires Siewert The existence of such feels may seem to some to mark the threshold for states or creatures that are really conscious. If an organism senses and responds in apt ways to its world but lacks such qualia, then it might count as conscious at best in a loose and less than literal sense.
Qualia problems in many forms—Can there be inverted qualia? Block a b, Shoemaker , Are qualia epiphenomenal? Jackson , Chalmers How could neural states give rise to qualia? Levine , McGinn —have loomed large in the recent past. But the What question raises a more basic problem of qualia: Absent such a model, factual or descriptive errors are all too likely. For example, claims about the unintelligibility of the link between experienced red and any possible neural substrate of such an experience sometimes treat the relevant color quale as a simple and sui generis property Levine , but phenomenal redness in fact exists within a complex color space with multiple systematic dimensions and similarity relations Hardin Color may be the exception in terms of our having a specific and well developed formal understanding of the relevant qualitative space, but it is not likely an exception with regard to the importance of such spaces to our understanding of qualitative properties in general Clark , P.
There are obviously important links between the phenomenal and the qualitative. Indeed qualia might be best understood as properties of phenomenal or experienced objects, but there is in fact far more to the phenomenal than raw feels. As Kant , Husserl , and generations of phenomenologists have shown, the phenomenal structure of experience is richly intentional and involves not only sensory ideas and qualities but complex representations of time, space, cause, body, self, world and the organized structure of lived reality in all its conceptual and nonconceptual forms.
Since many non-conscious states also have intentional and representational aspects, it may be best to consider phenomenal structure as involving a special kind of intentional and representational organization and content, the kind distinctively associated with consciousness Siewert See the entry on representational theories of consciousness. Answering the What question requires a careful account of the coherent and densely organized representational framework within which particular experiences are embedded.
Since most of that structure is only implicit in the organization of experience, it can not just be read off by introspection. Articulating the structure of the phenomenal domain in a clear and intelligible way is a long and difficult process of inference and model building Husserl Introspection can aid it, but a lot of theory construction and ingenuity are also needed.
There has been recent philosophical debate about the range of properties that are phenomenally present or manifest in conscious experience, in particular with respect to cognitive states such as believing or thinking. On the thin view, the phenomenal aspect of perceptual states as well is limited to basic sensory features; when one sees an image of Winston Churchill, one's perceptual phenomenology is limited only to the spatial aspects of his face.
On the thick view, the what-it-is-likeness of perceiving an image of Marilyn Monroe includes one's recognition of her history as part of the felt aspect of the experience, and beliefs and thoughts as well can and typically do have a distinctive nonsensory phenomenology. Both sides of the debate are well represented in the volume Cognitive Phenomenology Bayne and Montague Subjectivity is another notion sometimes equated with the qualitative or the phenomenal aspects of consciousness in the literature, but again there are good reason to recognize it, at least in some of its forms, as a distinct feature of consciousness—related to the qualitative and the phenomenal but different from each.
In particular, the epistemic form of subjectivity concerns apparent limits on the knowability or even the understandability of various facts about conscious experience Nagel , Van Gulick , Lycan On Thomas Nagel's account, facts about what it is like to be a bat are subjective in the relevant sense because they can be fully understood only from the bat-type point of view. Only creatures capable of having or undergoing similar such experiences can understand their what-it's-likeness in the requisite empathetic sense.
Facts about conscious experience can be at best incompletely understood from an outside third person point of view, such as those associated with objective physical science. A similar view about the limits of third-person theory seems to lie behind claims regarding what Frank Jackson's hypothetical Mary, the super color scientist, could not understand about experiencing red because of her own impoverished history of achromatic visual experience.
Whether facts about experience are indeed epistemically limited in this way is open to debate Lycan , but the claim that understanding consciousness requires special forms of knowing and access from the inside point of view is intuitively plausible and has a long history Locke Thus any adequate answer to the What question must address the epistemic status of consciousness, both our abilities to understand it and their limits Papineau , Chalmers See the entry on self-knowledge.
The perspectival structure of consciousness is one aspect of its overall phenomenal organization, but it is important enough to merit discussion in its own right. Insofar as the key perspective is that of the conscious self, the specific feature might be called self-perspectuality. Conscious experiences do not exist as isolated mental atoms, but as modes or states of a conscious self or subject Descartes , Searle , though pace Hume A visual experience of a blue sphere is always a matter of there being some self or subject who is appeared to in that way.
A sharp and stabbing pain is always a pain felt or experienced by some conscious subject. The self might be taken as the perspectival point from which the world of objects is present to experience Wittgenstein It provides not only a spatial and temporal perspective for our experience of the world but one of meaning and intelligibility as well.
The intentional coherence of the experiential domain relies upon the dual interdependence between self and world: Conscious organisms obviously differ in the extent to which they constitute a unified and coherent self, and they likely differ accordingly in the sort or degree of perspectival focus they embody in their respective forms of experience Lorenz Consciousness may not require a distinct or substantial self of the traditional Cartesian sort, but at least some degree of perspectivally self-like organization seems essential for the existence of anything that might count as conscious experience.
Experiences seem no more able to exist without a self or subject to undergo them than could ocean waves exist without the sea through which they move.
The Descriptive question thus requires some account of the self-perspectival aspect of experience and the self-like organization of conscious minds on which it depends, even if the relevant account treats the self in a relatively deflationary and virtual way Dennett , Unity is closely linked with the self-perspective, but it merits specific mention on its own as a key aspect of the organization of consciousness. Conscious systems and conscious mental states both involve many diverse forms of unity.
Some are causal unities associated with the integration of action and control into a unified focus of agency. Others are more representational and intentional forms of unity involving the integration of diverse items of content at many scales and levels of binding Cleeremans Some such integrations are relatively local as when diverse features detected within a single sense modality are combined into a representation of external objects bearing those features, e.
Other forms of intentional unity encompass a far wider range of contents. The content of one's present experience of the room in which one sits depends in part upon its location within a far larger structure associated with one's awareness of one's existence as an ongoing temporally extended observer within a world of spatially connected independently existing objects Kant , Husserl The individual experience can have the content that it does only because it resides within that larger unified structure of representation.
See the entry on unity of consciousness. Particular attention has been paid recently to the notion of phenomenal unity Bayne and its relation to other forms of conscious unity such as those involving representational, functional or neural integration. Some have argued that phenomenal unity can be reduced to representational unity Tye while others have denied the possibility of any such reduction Bayne Conscious mental states are typically regarded as having a representational or intentional aspect in so far as they are about things, refer to things or have satisfaction conditions. One's conscious visual experience correctly represent s the world if there are lilacs in a white vase on the table pace Travis , one's conscious memory is of the attack on the World Trade Center, and one's conscious desire is for a glass of cold water.
However, nonconscious states can also exhibit intentionality in such ways, and it is important to understand the ways in which the representational aspects of conscious states resemble and differ from those of nonconscious states Carruthers Searle offers a contrary view according to which only conscious states and dispositions to have conscious states can be genuinely intentional, but most theorists regard intentionality as extending widely into the unconscious domain. See the entry on consciousness and intentionality. One potentially important dimension of difference concerns so called transparency , which is an important feature of consciousness in two interrelated metaphoric senses, each of which has an intentional, an experiential and a functional aspect.
Conscious perceptual experience is often said to be transparent, or in G. When I look out at the wind-blown meadow, it is the undulating green grass of which I am aware not of any green property of my visual experience. Moore himself believed we could become aware of those latter qualities with effort and redirection of attention, though some contemporary transparency advocates deny it Harman , Tye , Kind Conscious thoughts and experiences are also transparent in a semantic sense in that their meanings seem immediately known to us in the very act of thinking them Van Gulick Our conscious mental states seem to have their meanings intrinsically or from the inside just by being what they are in themselves, by contrast with many externalist theories of mental content that ground meaning in causal, counterfactual or informational relations between bearers of intentionality and their semantic or referential objects.
The view of conscious content as intrinsically determined and internally self-evident is sometimes supported by appeals to brain in the vat intuitions, which make it seem that the envatted brain's conscious mental states would keep all their normal intentional contents despite the loss of all their normal causal and informational links to the world Horgan and Tienson There is continued controversy about such cases and about competing internalist Searle and externalist views Dretske of conscious intentionality.
Though semantic transparency and intrinsic intentionality have some affinities, they should not be simply equated, since it may be possible to accommodate the former notion within a more externalist account of content and meaning. Both semantic and sensory transparency obviously concern the representational or intentional aspects of consciousness, but they are also experiential aspects of our conscious life.
They are part of what it's like or how it feels phenomenally to be conscious. They also both have functional aspects, in so far as conscious experiences interact with each other in richly content-appropriate ways that manifest our transparent understanding of their contents. Whether partly in response to outer influences or entirely from within, each moment to moment sequence of experience grows coherently out of those that preceded it, constrained and enabled by the global structure of links and limits embodied in its underlying prior organization Husserl In that respect, consciousness is an autopoietic system, i.
As a conscious mental agent I can do many things such as scan my room, scan a mental image of it, review in memory the courses of a recent restaurant meal along with many of its tastes and scents, reason my way through a complex problem, or plan a grocery shopping trip and execute that plan when I arrive at the market. These are all routine and common activities, but each involves the directed generation of experiences in ways that manifest an implicit practical understanding of their intentional properties and interconnected contents Van Gulick Consciousness is a dynamic process, and thus an adequate descriptive answer to the What question must deal with more than just its static or momentary properties.
In particular, it must give some account of the temporal dynamics of consciousness and the ways in which its self-transforming flow reflects both its intentional coherence and the semantic self-understanding embodied in the organized controls through which conscious minds continually remake themselves as autopoietic systems engaged with their worlds.
The How question focuses on explanation rather than description. It asks us to explain the basic status of consciousness and its place in nature. Is it a fundamental feature of reality in its own right, or does its existence depend upon other nonconscious items, be they physical, biological, neural or computational? And if the latter, can we explain or understand how the relevant nonconscious items could cause or realize consciousness?
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Put simply, can we explain how to make something conscious out of things that are not conscious? The How question is not a single question, but rather a general family of more specific questions Van Gulick They all concern the possibility of explaining some sort or aspect of consciousness, but they vary in their particular explananda, the restrictions on their explanans, and their criteria for successful explanation.
For example, one might ask whether we can explain access consciousness computationally by mimicking the requisite access relations in a computational model. Or one might be concerned instead with whether the phenomenal and qualitative properties of a conscious creature's mind can be a priori deduced from a description of the neural properties of its brain processes. Both are versions of the How question, but they ask about the prospects of very different explanatory projects, and thus may differ in their answers Lycan It would be impractical, if not impossible, to catalog all the possible versions of the How question, but some of the main options can be listed.
Possible explananda would include the various sorts of state and creature consciousness distinguished above, as well as the seven features of consciousness listed in response to the What question. Those two types of explananda overlap and intersect. We might for example aim to explain the dynamic aspect either of phenomenal or of access consciousness. Or we could try to explain the subjectivity of either qualitative or meta-mental consciousness.
Not every feature applies to every sort of consciousness, but all apply to several. How one explains a given feature in relation to one sort of consciousness may not correspond with what is needed to explain it relative to another. The range of possible explanans is also diverse. In perhaps its broadest form, the How question asks how consciousness of the relevant sort could be caused or realized by nonconscious items, but we can generate a wealth of more specific questions by further restricting the range of the relevant explanans.
One might seek to explain how a given feature of consciousness is caused or realized by underlying neural processes, biological structures, physical mechanisms, functional or teleofunctional relations, computational organization, or even by nonconscious mental states. The prospects for explanatory success will vary accordingly.
In general the more limited and elementary the range of the explanans, the more difficult the problem of explaining how could it suffice to produce consciousness Van Gulick The third key parameter is how one defines the criterion for a successful explanation. One might require that the explanandum be a priori deducible from the explanans, although it is controversial whether this is either a necessary or a sufficient criterion for explaining consciousness Jackson Its sufficiency will depend in part on the nature of the premises from which the deduction proceeds.
As a matter of logic, one will need some bridge principles to connect propositions or sentences about consciousness with those that do not mention it. If one's premises concern physical or neural facts, then one will need some bridge principles or links that connect such facts with facts about consciousness Kim Brute links, whether nomic or merely well confirmed correlations, could provide a logically sufficient bridge to infer conclusions about consciousness. But they would probably not allow us to see how or why those connections hold, and thus they would fall short of fully explaining how consciousness exists Levine , , McGinn One could legitimately ask for more, in particular for some account that made intelligible why those links hold and perhaps why they could not fail to do so.
A familiar two-stage model for explaining macro-properties in terms of micro-substrates is often invoked. In the first step, one analyzes the macro-property in terms of functional conditions, and then in the second stage one shows that the micro-structures obeying the laws of their own level nomically suffice to guarantee the satisfaction of the relevant functional conditions Armstrong , Lewis Moreover, the model makes intelligible how the liquidity is produced by the micro-properties.
A satisfactory explanation of how consciousness is produced might seem to require a similar two stage story. Without it, even a priori deducibility might seem explanatorily less than sufficient, though the need for such a story remains a matter of controversy Block and Stalnaker , Chalmers and Jackson Our current inability to supply a suitably intelligible link is sometimes described, following Joseph Levine , as the existence of an explanatory gap , and as indicating our incomplete understanding of how consciousness might depend upon a nonconscious substrate, especially a physical substrate.
The basic gap claim admits of many variations in generality and thus in strength. In perhaps its weakest form, it asserts a practical limit on our present explanatory abilities; given our current theories and models we can not now articulate an intelligible link. A stronger version makes an in principle claim about our human capacities and thus asserts that given our human cognitive limits we will never be able to bridge the gap. To us, or creatures cognitively like us, it must remain a residual mystery McGinn Colin McGinn has argued that given the inherently spatial nature of both our human perceptual concepts and the scientific concepts we derive from them, we humans are not conceptually suited for understanding the nature of the psychophysical link.
Facts about that link are as cognitively closed to us as are facts about multiplication or square roots to armadillos. They do not fall within our conceptual and cognitive repertoire. An even stronger version of the gap claim removes the restriction to our cognitive nature and denies in principle that the gap can be closed by any cognitive agents. Those who assert gap claims disagree among themselves about what metaphysical conclusions, if any, follow from our supposed epistemic limits.
Levine himself has been reluctant to draw any anti-physicalist ontological conclusions Levine , On the other hand some neodualists have tried to use the existence of the gap to refute physicalism Foster , Chalmers The stronger one's epistemological premise, the better the hope of deriving a metaphysical conclusion. Thus unsurprisingly, dualist conclusions are often supported by appeals to the supposed impossibility in principle of closing the gap.
If one could see on a priori grounds that there is no way in which consciousness could be intelligibly explained as arising from the physical, it would not be a big step to concluding that it in fact does not do so Chalmers However, the very strength of such an epistemological claim makes it difficult to assume with begging the metaphysical result in question. Thus those who wish to use a strong in principle gap claim to refute physicalism must find independent grounds to support it.
Some have appealed to conceivability arguments for support, such as the alleged conceivability of zombies molecularly identical with conscious humans but devoid of all phenomenal consciousness Campbell , Kirk , Chalmers Other supporting arguments invoke the supposed non-functional nature of consciousness and thus its alleged resistance to the standard scientific method of explaining complex properties e. Such arguments avoid begging the anti-physicalist question, but they themselves rely upon claims and intuitions that are controversial and not completely independent of one's basic view about physicalism.
Discussion on the topic remains active and ongoing. Our present inability to see any way of closing the gap may exert some pull on our intuitions, but it may simply reflect the limits of our current theorizing rather than an unbridgeable in principle barrier Dennett Moreover, some physicalists have argued that explanatory gaps are to be expected and are even entailed by plausible versions of ontological physicalism, ones that treat human agents as physically realized cognitive systems with inherent limits that derive from their evolutionary origin and situated contextual mode of understanding Van Gulick , ; McGinn , Papineau , On this view, rather than refuting physicalism, the existence of explanatory gaps may confirm it.
Discussion and disagreement on these topics remains active and ongoing. As the need for intelligible linkage has shown, a priori deducibility is not in itself obviously sufficient for successful explanation Kim , nor is it clearly necessary.
Some weaker logical link might suffice in many explanatory contexts. We can sometimes tell enough of a story about how facts of one sort depend upon those of another to satisfy ourselves that the latter do in fact cause or realize the former even if we can not strictly deduce all the former facts from the latter. Strict intertheoretical deduction was taken as the reductive norm by the logical empiricist account of the unity of science Putnam and Oppenheim , but in more recent decades a looser nonreductive picture of relations among the various sciences has gained favor.
Economics is often cited as an example Fodor , Searle Economic facts may be realized by underlying physical processes, but no one seriously demands that we be able to deduce the relevant economic facts from detailed descriptions of their underlying physical bases or that we be able to put the concepts and vocabulary of economics in tight correspondence with those of the physical sciences.
All that we require is some general and less than deductive understanding of how economic properties and relations might be underlain by physical ones. Thus one might opt for a similar criterion for interpreting the How question and for what counts as explaining how consciousness might be caused or realized by nonconscious items. However, some critics, such as Kim , have challenged the coherence of any view that aims to be both non-reductive and physicalist, though supporters of such views have replied in turn Van Gulick Others have argued that consciousness is especially resistant to explanation in physical terms because of the inherent differences between our subjective and objective modes of understanding.
Thomas Nagel famously argued that there are unavoidable limits placed on our ability to understand the phenomenology of bat experience by our inability to empathetically take on an experiential perspective like that which characterizes the bat's echo-locatory auditory experience of its world. Given our inability to undergo similar experience, we can have at best partial understanding of the nature of such experience. No amount of knowledge gleaned from the external objective third-person perspective of the natural sciences will supposedly suffice to allow us to understand what the bat can understand of its own experience from its internal first-person subjective point of view.
The How question thus subdivides into a diverse family of more specific questions depending upon the specific sort or feature of consciousness one aims to explain, the specific restrictions one places on the range of the explanans and the criterion one uses to define explanatory success. Some of the resulting variants seem easier to answer than others. Positive answers to some versions of the How questions seem near at hand, but others appear to remain deeply baffling. Nor should we assume that every version has a positive answer.
If dualism is true, then consciousness in at least some of its types may be basic and fundamental. If so,we will not be able to explain how it arises from nonconscious items since it simply does not do so. One's view of the prospects for explaining consciousness will typically depend upon one's perspective. Optimistic physicalists will likely see current explanatory lapses as merely the reflection of the early stage of inquiry and sure to be remedied in the not too distant future Dennett , Searle , P.
To dualists, those same impasses will signify the bankruptcy of the physicalist program and the need to recognize consciousness as a fundamental constituent of reality in its own right Robinson , Foster , , Chalmers What one sees depends in part on where one stands, and the ongoing project of explaining consciousness will be accompanied by continuing debate about its status and prospects for success. The functional or Why question asks about the value or role or consciousness and thus indirectly about its origin. Does it have a function , and if so what is it? Does it make a difference to the operation of systems in which it is present, and if so why and how?
If consciousness exists as a complex feature of biological systems, then its adaptive value is likely relevant to explaining its evolutionary origin, though of course its present function, if it has one, need not be the same as that it may have had when it first arose. Adaptive functions often change over biological time. Questions about the value of consciousness also have a moral dimension in at least two ways. We are inclined to regard an organism's moral status as at least partly determined by the nature and extent to which it is conscious, and conscious states, especially conscious affective states such as pleasures and pains, play a major role in many of the accounts of value that underlie moral theory Singer As with the What and How questions, the Why question poses a general problem that subdivides into a diversity of more specific inquiries.
In so far as the various sorts of consciousness, e. Thus the Why question may well not have a single or uniform answer. Perhaps the most basic issue posed by any version of the Why question is whether or not consciousness of the relevant sort has any causal impact at all. If it has no effects and makes no causal difference whatsoever, then it would seem unable to play any significant role in the systems or organisms in which it is present, thus undercutting at the outset most inquiries about its possible value.
Nor can the threat of epiphenomenal irrelevance be simply dismissed as an obvious non-option, since at least some forms of consciousness have been seriously alleged in the recent literature to lack causal status. See the entry on epiphenomenalism. Such worries have been raised especially with regard to qualia and qualitative consciousness Huxley , Jackson , Chalmers , but challenges have also been leveled against the causal status of other sorts including meta-mental consciousness Velmans Both metaphysical and empirical arguments have been given in support of such claims.
Among the former are those that appeal to intuitions about the conceivability and logical possibility of zombies, i. Some Kirk , Chalmers assert such beings are possible in worlds that share all our physical laws, but others deny it Dennett , Levine If they are possible in such worlds, then it would seem to follow that even in our world, qualia do not affect the course of physical events including those that constitute our human behaviors. If those events unfold in the same way whether or not qualia are present, then qualia appear to be inert or epiphenomenal at least with respect to events in the physical world.
However, such arguments and the zombie intuitions on which they rely are controversial and their soundness remains in dispute Searle , Yablo , Balog Arguments of a far more empirical sort have challenged the causal status of meta-mental consciousness, at least in so far as its presence can be measured by the ability to report on one's mental state. Scientific evidence is claimed to show that consciousness of that sort is neither necessary for any type of mental ability nor does it occur early enough to act as a cause of the acts or processes typically thought to be its effects Velmans According to those who make such arguments, the sorts of mental abilities that are typically thought to require consciousness can all be realized unconsciously in the absence of the supposedly required self-awareness.
Moreover, even when conscious self-awareness is present, it allegedly occurs too late to be the cause of the relevant actions rather than their result or at best a joint effect of some shared prior cause Libet Self-awareness or meta-mental consciousness according to these arguments turns out to be a psychological after-effect rather than an initiating cause, more like a post facto printout or the result displayed on one's computer screen than like the actual processor operations that produce both the computer's response and its display.
Once again the arguments are controversial, and both the supposed data and their interpretation are subjects of lively disagreement see Flanagan , and commentaries accompanying Velmans Though the empirical arguments, like the zombie claims, require one to consider seriously whether some forms of consciousness may be less causally potent than is typically assumed, many theorists regard the empirical data as no real threat to the causal status of consciousness.
If the epiphenomenalists are wrong and consciousness, in its various forms, is indeed causal, what sorts of effects does it have and what differences does it make? How do mental processes that involve the relevant sort of consciousness differ form those that lack it? What function s might consciousness play? The following six sections 6. Though the various functions overlap to some degree, each is distinct, and they differ as well in the sorts of consciousness with which each is most aptly linked.
Increased flexibility and sophistication of control. Conscious mental processes appear to provide highly flexible and adaptive forms of control. Though unconscious automatic processes can be extremely efficient and rapid, they typically operate in ways that are more fixed and predetermined than those which involve conscious self-awareness Anderson Conscious awareness is thus of most importance when one is dealing with novel situations and previously unencountered problems or demands Penfield , Armstrong Standard accounts of skill acquisition stress the importance of conscious awareness during the initial learning phase, which gradually gives way to more automatic processes of the sort that require little attention or conscious oversight Schneider and Shiffrin Conscious processing allows for the construction or compilation of specifically tailored routines out of elementary units as well as for the deliberate control of their execution.
There is a familiar tradeoff between flexibility and speed; controlled conscious processes purchase their customized versatility at the price of being slow and effortful in contrast to the fluid rapidity of automatic unconscious mental operations Anderson The relevant increases in flexibility would seem most closely connected with the meta-mental or higher-order form of consciousness in so far as the enhanced ability to control processes depends upon greater self-awareness.
However, flexibility and sophisticated modes of control may be associated as well with the phenomenal and access forms of consciousness. Enhanced capacity for social coordination. Consciousness of the meta-mental sort may well involve not only an increase in self-awareness but also an enhanced understanding of the mental states of other minded creatures, especially those of other members of one's social group Humphreys Creatures that are conscious in the relevant meta-mental sense not only have beliefs, motives, perceptions and intentions but understand what it is to have such states and are aware of both themselves and others as having them.
This increase in mutually shared knowledge of each other's minds, enables the relevant organisms to interact, cooperate and communicate in more advanced and adaptive ways. Although meta-mental consciousness is the sort most obviously linked to such a socially coordinative role, narrative consciousness of the kind associated with the stream of consciousness is also clearly relevant in so far as it involves the application to one's own case of the interpretative abilities that derive in part from their social application Ryle , Dennett , More unified and densely integrated representation of reality.
Conscious experience presents us with a world of objects independently existing in space and time. Those objects are typically present to us in a multi-modal fashion that involves the integration of information from various sensory channels as well as from background knowledge and memory. Conscious experience presents us not with isolated properties or features but with objects and events situated in an ongoing independent world, and it does so by embodying in its experiential organization and dynamics the dense network of relations and interconnections that collectively constitute the meaningful structure of a world of objects Kant , Husserl , Campbell Of course, not all sensory information need be experienced to have an adaptive effect on behavior.
Adaptive non-experiential sensory-motor links can be found both in simple organisms, as well as in some of the more direct and reflexive processes of higher organisms. But when experience is present, it provides a more unified and integrated representation of reality, one that typically allows for more open-ended avenues of response Lorenz Consider for example the representation of space in an organism whose sensory input channels are simply linked to movement or to the orientation of a few fixed mechanisms such as those for feeding or grabbing prey, and compare it with that in an organism capable of using its spatial information for flexible navigation of its environment and for whatever other spatially relevant aims or goals it may have, as when a person visually scans her office or her kitchen Gallistel It is representation of this latter sort that is typically made available by the integrated mode of presentation associated with conscious experience.
The unity of experienced space is just one example of the sort of integration associated with our conscious awareness of an objective world. This integrative role or value is most directly associated with access consciousness, but also clearly with the larger phenomenal and intentional structure of experience. It is relevant even to the qualitative aspect of consciousness in so far as qualia play an important role in our experience of unified objects in a unified space or scene. It is intimately tied as well to the transparency of experience described in response to the What question, especially to semantic transparency Van Gulick Integration of information plays a major role in several current neuro-cognitive theories of consciousness especially Global Workspace theories see section 9.
More global informational access. The information carried in conscious mental states is typically available for use by a diversity of mental subsystems and for application to a wide range of potential situations and actions Baars Nonconscious information is more likely to be encapsulated within particular mental modules and available for use only with respect to the applications directly connected to that subsystem's operation Fodor Making information conscious typically widens the sphere of its influence and the range of ways it which it can be used to adaptively guide or shape both inner and outer behavior.
This particular role is most directly and definitionally tied to the notion of access consciousness Block , but meta-mental consciousness as well as the phenomenal and qualitative forms all seem plausibly linked to such increases in the availability of information Armstrong , Tye Diverse cognitive and neuro-cognitive theories incorporate access as a central feature of consciousness and conscious processing. Increased freedom of choice or free will.
The issue of free will remains a perennial philosophical problem, not only with regard to whether or not it exists but even as to what it might or should consist in Dennett , van Inwagen , Hasker , Wegner See the entry on free will. The notion of free will may itself remain too murky and contentious to shed any clear light on the role of consciousness, but there is a traditional intuition that the two are deeply linked.
Consciousness has been thought to open a realm of possibilities, a sphere of options within which the conscious self might choose or act freely. At a minimum, consciousness might seem a necessary precondition for any such freedom or self-determination Hasker How could one engage in the requisite sort of free choice, while remaining solely within the unconscious domain? How can one determine one's own will without being conscious of it and of the options one has to shape it.
The freedom to chose one's actions and the ability to determine one's own nature and future development may admit of many interesting variations and degrees rather than being a simple all or nothing matter, and various forms or levels of consciousness might be correlated with corresponding degrees or types of freedom and self-determination Dennett , The link with freedom seems strongest for the meta-mental form of consciousness given its emphasis on self-awareness, but potential connections also seem possible for most of the other sorts as well.
At least some conscious states appear to have the motive force they do intrinsically. In particular, the functional and motivational roles of conscious affective states, such as pleasures and pains, seem intrinsic to their experiential character and inseparable from their qualitative and phenomenal properties, though the view has been challenged Nelkin , Rosenthal The attractive positive motivational aspect of a pleasure seems a part of its directly experienced phenomenal feel, as does the negative affective character of a pain, at least in the case of normal non-pathological experience.
There is considerable disagreement about the extent to which the feel and motive force of pain can dissociate in abnormal cases, and some have denied the existence of such intrinsically motivating aspects altogether Dennett However, at least in the normal case, the negative motivational force of pain seems built right into the feel of the experience itself.
Just how this might be so remains less than clear, and perhaps the appearance of intrinsic and directly experienced motivational force is illusory. But if it is real, then it may be one of the most important and evolutionarily oldest respects in which consciousness makes a difference to the mental systems and processes in which it is present Humphreys Other suggestions have been made about the possible roles and value of consciousness, and these six surely do not exhaust the options. Nonetheless, they are among the most prominent recent hypotheses, and they provide a fair survey of the sorts of answers that have been offered to the Why question by those who believe consciousness does indeed make a difference.
One further point requires clarification about the various respects in which the proposed functions might answer the Why question. In particular one should distinguish between constitutive cases and cases of contingent realization. In the former, fulfilling the role constitutes being conscious in the relevant sense, while in the latter case consciousness of a given sort is just one way among several in which the requisite role might be realized Van Gulick For example, making information globally available for use by a wide variety of subsystems and behavioral applications may constitute its being conscious in the access sense.
By contrast, even if the qualitative and phenomenal forms of consciousness involve a highly unified and densely integrated representation of objective reality, it may be possible to produce representations having those functional characteristics but which are not qualitative or phenomenal in nature.
The fact that in us the modes of representation with those characteristics also have qualitative and phenomenal properties may reflect contingent historical facts about the particular design solution that happened to arise in our evolutionary ancestry. If so, there may be quite other means of achieving a comparable result without qualitative or phenomenal consciousness. Whether this is the right way to think about phenomenal and qualitative conscious is unclear; perhaps the tie to unified and densely integrated representation is in fact as intimate and constitutive as it seems to be in the case of access consciousness Carruthers Regardless of how that issue gets resolved, it is important to not to conflate constitution accounts with contingent realization accounts when addressing the function of consciousness and answering the question of why it exists Chalmers In response to the What, How and Why questions many theories of consciousness have been proposed in recent years.
However, not all theories of consciousness are theories of the same thing. They vary not only in the specific sorts of consciousness they take as their object, but also in their theoretical aims. Perhaps the largest division is between general metaphysical theories that aim to locate consciousness in the overall ontological scheme of reality and more specific theories that offer detailed accounts of its nature, features and role.
The line between the two sorts of theories blurs a bit, especially in so far as many specific theories carry at least some implicit commitments on the more general metaphysical issues. Nonetheless, it is useful to keep the division in mind when surveying the range of current theoretical offerings. Dualist theories regard at least some aspects of consciousness as falling outside the realm of the physical,but specific forms of dualism differ in just which aspects those are. See the entry on dualism. Substance dualism , such as traditional Cartesian dualism Descartes , asserts the existence of both physical and non-physical substances.
Such theories entail the existence of non-physical minds or selves as entities in which consciousness inheres. Though substance dualism is at present largely out of favor, it does have some contemporary proponents Swinburne , Foster , Property dualism in its several versions enjoys a greater level of current support.
All such theories assert the existence of conscious properties that are neither identical with nor reducible to physical properties but which may nonetheless be instantiated by the very same things that instantiate physical properties. In that respect they might be classified as dual aspect theories. They take some parts of reality—organisms, brains, neural states or processes—to instantiate properties of two distinct and disjoint sorts: Dual aspect or property dualist theories can be of at least three different types.
Fundamental property dualism regards conscious mental properties as basic constituents of reality on a par with fundamental physical properties such as electromagnetic charge. They may interact in causal and law-like ways with other fundamental properties such as those of physics, but ontologically their existence is not dependent upon nor derivative from any other properties Chalmers Emergent property dualism treats conscious properties as arising from complex organizations of physical constituents but as doing so in a radical way such that the emergent result is something over and above its physical causes and is not a priori predictable from nor explicable in terms of their strictly physical natures.
The coherence of such emergent views has been challenged Kim but they have supporters Hasker Neutral monist property dualism treats both conscious mental properties and physical properties as in some way dependent upon and derivative from a more basic level of reality, that in itself is neither mental nor physical Russell , Strawson However, if one takes dualism to be a claim about there being two distinct realms of fundamental entities or properties, then perhaps neutral monism should not be classified as a version of property dualism in so far as it does not regard either mental or physical properties as ultimate or fundamental.
Panpsychism might be regarded as a fourth type of property dualism in that it regards all the constituents of reality as having some psychic, or at least proto-psychic, properties distinct from whatever physical properties they may have Nagel Indeed neutral monism might be consistently combined with some version of panprotopsychism Chalmers according to which the proto-mental aspects of micro-constituents can give rise under suitable conditions of combination to full blown consciousness.
See the entry on panpsychism. The nature of the relevant proto-psychic aspect remains unclear, and such theories face a dilemma if offered in hope of answering the Hard Problem. Either the proto-psychic properties involve the sort of qualitative phenomenal feel that generates the Hard Problem or they do not. If they do, it is difficult to understand how they could possibly occur as ubiquitous properties of reality.
How could an electron or a quark have any such experiential feel? However, if the proto-psychic properties do not involve any such feel, it is not clear how they are any better able than physical properties to account for qualitative consciousness in solving the Hard Problem. A more modest form of panpsychism has been advocated by the neuroscientist Giulio Tononi and endorsed by other neuroscientists including Christof Koch This version derives from Tononi's integrated information theory IIT of consciousness that identifies consciousness with integrated information which can exist in many degrees see section 9.
According to IIT, even a simple indicator device such as a single photo diode possesses some degree of integrated information and thus some limited degree of consciousness, a consequence which both Tononi and Koch embrace as a form of panpsychism. A variety of arguments have been given in favor of dualist and other anti-physicalist theories of consciousness. Some are largely a priori in nature such as those that appeal to the supposed conceivability of zombies Kirk , Chalmers or versions of the knowledge argument Jackson , which aim to reach an anti-physicalist conclusion about the ontology of consciousness from the apparent limits on our ability to fully understand the qualitative aspects of conscious experience through third-person physical accounts of the brain processes.
See Jackson , for a contrary view; see also entries on Zombies , and Qualia: The Knowledge Argument Other arguments for dualism are made on more empirical grounds, such as those that appeal to supposed causal gaps in the chains of physical causation in the brain Eccles and Popper or those based on alleged anomalies in the temporal order of conscious awareness Libet , Dualist arguments of both sorts have been much disputed by physicalists P.