What is Consciousness?

Dietrich [Dietrich 2007] said that “there is no accepted definition of consciousness” which is surprising since it is our common direct experience. Nevertheless, consciousness is a word which is used in a number of distinct ways both in ordinary conversation and also in more technical discussions. This can lead to confusion when the word is used loosely.

Wakefulness

Maybe the most widely used meaning of the word consciousness is “wakefulness”. When we are awake, we are conscious. When we are asleep then, with the possible exception of dreaming, we are not. If we are “knocked out” then we lose consciousness and are then described as unconscious. Ultimately, when we are no longer alive then we no longer have consciousness.

It is our common experience that there are degrees of consciousness in this sense of the word. During the process of waking up from a deep sleep or coming round after an anaesthetic, people are likely to experience a gradual change from unconsciousness to full consciousness with some states in between. It is not like flicking a switch.

Degrees of wakefulness are normally accompanied by certain objective indications such as the Glasgow coma scale or the Grady Coma Scale . In each case the criteria for degree of consciousness is the responsiveness of the person to sensory stimuli, particularly pain. These criteria are not reliable as there have been many cases of people who were considered unresponsive according to the above descriptions but who were found to be aware and able to communicate as shown in [Cyranoski 2012]

This is by no means the whole story and there is more to consciousness than wakefulness. A number of different types of consciousness have been identified by various workers in the field, including Ned Block who distinguishes different ways in which the word “consciousness” can be used [Block 1995]. The most notable distinction he makes is between what he calls “access consciousness” and “phenomenal consciousness”.

Access consciousness

If we are “access conscious” of something then that something is “poised for control of speech, reasoning and action” [Block 1995] or as “directly available for global control” [Block 2002].

In principle, access consciousness could, without much controversy, be ascribed to a computer system. A computer has memory, it has processors which can make use of the data stored in memory, it has output ports through which actions can follow. With modern technology, one of these outputs could be speech. Therefore, by Block’s definition, it has access consciousness.  As such, there are no conceptual problems introduced by this form of consciousness.

For this reason, investigation of access consciousness has been referred to, originally by Chalmers, as the (relatively) “easy problem”[Chalmers 1995]. Even though not all the answers are known and there is much research left to be done, there is no reason to believe that answers cannot eventually be found.

Phenomenal consciousness

It is tricky, if not impossible, to define phenomenal consciousness and it is best illustrated by example. Consider someone who is watching a sunset. They certainly have knowledge which can immediately be used to prompt speech, reasoning and action, so the person is “access conscious”, or “aware” of the sunset. However, in addition to that, there is the experience of watching a sunset which goes beyond factual knowledge[Farrell 1950]. To use Nagal’s description [Nagal 1974], there is “something it is like” to see a sunset. There is an appreciation of beauty, there might be a sense of peace and well-being or any number of similar feelings. In other words, there is an experience over and above the physical perception and this experience is something which is difficult, if not impossible, to communicate to others. This is akin to the well known problem of how to describe to a blind person what it is like to see red. It cannot be done [Ravenscroft 2005]. Or if a person has never tasted Marmite the only way to describe what it tastes like is by reference to other tastes, such as salty and yeasty. It cannot be done outside the domain of tastes. A complete chemical description of Marmite would not help in describing the experience.

The subjective and essentially private aspect of phenomenal conscious experience is developed by Soren Kierkegaard who said “human existence is a mode of being in which subjectivity is the truth and […] such truth cannot be communicated directly”  [Broudy 1961, page 225] “Subjectivity is truth” [Kierkegaard 1849].

These experiences, called “qualia” in the literature, are a characteristic of phenomenal consciousness and, although they are usually accompanied by access consciousness, they are not identical with it. It is certainly possible to have access consciousness without phenomenal consciousness as described above for the case of a computer. It is also possible to have phenomenal consciousness without access consciousness although, in humans, this is only likely to happen if there has been brain damage.

Unlike access consciousness, “phenomenal consciousness” has so far only been attributed to biological structures.

A comparison between Access and Phenomenal consciousness is given in the table.

Wakefulness and access consciousness presents no conceptual or ontological problems. Phenomenal consciousness does and, indeed, is the basis of all questions.