Consciousness

• seCtIon tWo: tHe BRAIn

TOP

(a)

Parietal

lobe

Frontal

lobe

Te mporal

lobe

Occipital

lobe

FRONT

Primary

motor cortex

Primary

somatosensory

cortex

Primary auditory

cortex (mostly

hidden from view)

Primary visual

cortex, V1 (mostly

hidden from view)

Central

fissure

Brainstem Cerebellum

Spinal

cord

Broca’s

area

Wernicke’s

area

Motor

association

cortex

Somatosensory

association

cortex

Visual

association

cortex

Aud

itory^

assoc

iation^ co

rtex

Visua

l associat

ion^ cortex

Cingulate

gyrus Cerebral

cortex

Corpus

callosum

Colliculi

Aqueduct

Cerebellum

4th ventricle

Medulla

Pons

Midbrain

Pituitary

stalk

Optic

nerve

Hypothalamus

Thalamus

(b)

animal ‘an attribute which it makes

sense to ascribe only to the animal as

a whole’ (Bennett and Hacker, 2003,

p. 240). British philosopher Andy

Clark (Clark and Chalmers, 1998;

Clark, 2008) conceives of a person as

an extended or ‘supersized’ system

whose ‘operations are realized not

in the neural system alone but in

the whole embodied system located

in the world’ (Clark, 2008, p.  14).

(We will return to these views in

Chapter 8.)

Mysterians also say no, but for a

different reason. Many of them

claim that we can never understand

consciousness: it is simply not some-

thing the human mind is capable of

grasping. Some, like Steven Pinker

(2007, p. 6), admit that we might one

day be able to, but think it is pretty

unlikely:

The brain is a product of

evolution, and just as animal

brains have their limitations,

we have ours. Our brains

can’t hold a hundred

numbers in memory, can’t

visualize seven-dimensional

space and perhaps

can’t intuitively grasp

why neural information

processing observed from

the outside should give rise

to subjective experience

on the inside. This is where

I place my bet, though I admit that the theory could be demolished

when an unborn genius – a Darwin or Einstein of consciousness –

comes up with a flabbergasting new idea that suddenly makes it all

clear to us.

No one denies that the brain is relevant to consciousness; they just disagree

fundamentally about its role. Looking inside a brain reveals a mystery whichever

method you use. Dissecting a human brain with a scalpel and looking with the

naked eye reveals a few pounds of soft greyish tissue with a wrinkly surface and

not much inner detail. Staining a slice of brain and looking through a microscope

shows billions of neurons with vast spreading trees of axons and dendrites.

Attaching electrodes to the scalp provides a readout of activity on the surface,

FIGURE 4.1 • Schematic illustrations of the human
brain. (a) A lateral view (i.e.,
looking at the outside of one side
of the brain) of the left hemisphere
showing the four lobes of the
cortex and the various sensory and
association areas. (b) A medial view
(i.e., looking at the inside surface
of one half of the brain as though
it has been cut through the middle)
of the right hemisphere. The corpus
callosum consists of over 200 million
nerve axons connecting the two
hemispheres. Thalamic and midbrain
structures are also shown.