What is Consciousness?

What is consciousness? This is a very difficult question, and one subject to very loose and muddy definitions. Indeed, different people have either unformed ideas on the matter, or have widely differing concepts of the concept of consciousness. Viewed from a purely practical perspective, part of the question can be answered by examining which animals and humans clearly have evident and provable periods of consciousness and unconsciousness, as defined by sleep and general anesthesia. The list below describing recognized consciousness in mammals is very informative.

• A normally healthy human is unconscious during sleep and general anesthesia, and conscious when awake.
• A drooling, totally demented human is unconscious during sleep and general anesthesia, and conscious when awake.
• A drooling, misformed, severely mentally retarded human is unconscious during sleep and general anesthesia, and conscious when awake.
• Horses, cows, pigs, dogs and cats are clearly unconscious during sleep and general anesthesia, and conscious when awake.
• Monkeys, rabbits, ferrets, rats and mice are clearly unconscious during sleep and general anesthesia, and conscious when awake.

What does this list imply?

This is just a list of some easily recognized examples of the presence and absence consciousness in familiar mammals, and excludes the fact that many other animal species such as reptiles, fish, and birds also manifest periods of consciousness and unconsciousness in the same manner as the mammals listed above (Bringmann 2018, Siegel 2008). Yet nothing indicates that they manifest consciousness in the manner as defined in these dictionary definitions of consciousness.

[Consciousness] Is the state of knowing what goes on around one… (Webster Dictionary 1991)

[Consciousness means being] Inwardly sensible or aware… (Shorter Oxford Dictionary 1956)

No-one expects a mouse or dog to have the same intelligence, self-awareness, tool-making, society-building, environmental manipulation abilities as a normally functioning human. Indeed, while they possess the same basic brain structures as humans, as well as expressing basic emotions such as fear, contentment and happiness, no animals other than humans have ever developed the use of tools, or have purposefully changed and influenced their environments as have humans.

The true meaning of “consciousness”

In the absence of consciousness in humans and animals, there is no voluntary directed behavior, there are no expressions of mental activity such as personality, voluntary directed actions or behavior, emotions such as fear, contentment or happiness. Accordingly, consciousness is that property of brain function making attributes of mind such as personality, emotions, awareness, and memory possible. One neurologist expressed the subject of consciousness in this way.

… wakefulness refers to the sub-state that permits open eyes and a degree of motor arousal (i.e. wakefulness defines the level of consciousness); awareness refers to the sub-state that enables experience of thoughts, personality, memories, and emotions (i.e. awareness defines the content of consciousness. Although wakefulness and awareness are intimately connected—in general, one has to be awake to be aware—it is possible to identify circumstances under which they are dissociated: … (Gawryluk 2010)

All the above makes it possible to provide a definition of consciousness in terms of a computer metaphor as below.

Consciousness is similar to a computer operating system which when present and active, makes programs like properties of mind such as emotions, personality, awareness, and memory possible.

This is a clear and logical way to define consciousness without the necessity of any real understanding of its nature, or the level of neuronal complexity required to manifest consciousness. One thing we certainly do know about consciousness, is that more than 80 years of medical science repeatedly reveals consciousness to originate, or be generated by structures within the brainstem, the evolutionary most primitive part of the brain (see diagram).

anesthesia and the soul

The “brainstem” in the human consists of the midbrain, the pons, and the medulla. This is the most primitive part of the brain, as is evidenced by the presence of the same structures and functions in the brains of all vertebrate animals such as fish, mammals, reptiles, and birds.

This is the way consciousness is viewed in the book “Anesthesia & the Soul”. Readers can download the book by pressing the button below.


  1. Bringmann H, (2018), Sleep active neurons: conserved motors of sleep. Genetics, 208: 1279-1289.
  2. Gawryluk JR, et al, (2010), Improving the clinical assessment of consciousness with advances in electrophysiological and neuroimaging techniques. BMC Neurology, 10: 11.
  3. Siegel JM, (2008), Do all animals sleep? Trends in Neurosciences, 31: 208-213.

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