particular pattern of neuralWring) possessphenomenal properties? There is
something distinctive that a conscious experience, or a conscious feeling,
or a conscious visual image,is like. And it seems that no one except those
who have enjoyed such states can everknowwhat they are like. How can
this phenomenal aspect of our conscious mental lives ever be explained or
accounted for within a physicalist framework? There are those who re-
spond by saying that, indeed, conscious states arenotphysical (Jackson,
1982); and there are those who say that we can neverunderstandhow
conscious statescan bephysical, while continuing to believe that they are
(Nagel, 1974, 1986; McGinn, 1991).
Equally, phenomenal consciousness presents a challenge to any claim of
functionalism and theory-theory to providecomprehensiveaccounts of the
mental. For it seems that we can describe systems which would be func-
tionally and theoretically equivalent to the human mind, but which we
would not, intuitively, want to say were conscious, or were subjects of
phenomenal feelings. And ‘inverted qualia’ and ‘absent qualia’ thought-
experiments seem to show that the phenomenal qualities of our experien-
ces cannot be given a functional characterisation. For if a person could be
functionally equivalent to me while having their red and green experiences
inverted, or absent altogether, then it seems that the felt quality of my
experience of redness cannot be any sort of functional characteristic
(Block, 1978, 1990; Shoemaker, 1986; Searle, 1992).
More generally, phenomenal consciousness can be seen as a challenge to
science. Indeed, many scientists regard consciousness (together with the
question of the origin of the universe) as one of the ‘Wnal frontiers’ – a last
bastion of mystery which is yet to fall to the onslaught of scientiWc
explanation. And some, like Penrose (1989, 1994), have thought that the
solution of the problem might provide the key to problems elsewhere in
science, particularly in fundamental physics. Our task will be to see
whether there are any reasons of principle why phenomenal consciousness
can never be explained; and (following a negative answer) to see what
progress has actually been made in explaining it.
We thus have distinctions betweencreature-consciousness (intransitive
and transitive), on the one hand, andmental-state-consciousness on the
other. And then within the latter, we have distinctions betweenphenomenal
consciousness and various forms of functionally deWned state-conscious-
ness (Wrst-order access-consciousness, higher-order-consciousness, and so
on). Our main task will be to consider whether phenomenal consciousness
can be explained in terms of some or other functionally deWnable notion.
But there is one further distinction to be placed on the map, lest it be
confused with any of the notions already discussed – and that isself-
consciousness.
230 Consciousness: theWnal frontier?