thesis

sciousness’) is not logically supervenient on functional cognition (‘awareness’). Nevertheless,
he does think that awareness is naturally supervenient on consciousness (220):
Where there is consciousness, there is awareness. My visual experience of a red book upon my
table is accompanied by a functional perception of the book. Optical stimulation is processed
and transformed, and my perceptual systems register that there is an object of such-and-such
shape and colour on the table, with this information available in the control of behaviour.
The principle of structural coherence takes this one step further, suggesting not only that
the existence of consciousness depends on that of awareness, but that the structure of con-
sciousness mirrors that of awareness (224–5):
Similarities and differences between experiences correspond to similarities and differences
represented in awareness; the geometry of experience corresponds to the geometry of aware-
ness; and so on…
Thus, the contents of our subjective consciousness will very closely mirror those of our
functional awareness. This seems to be borne out by empirical observation and is essential to
any sense of rationality – if our subjective experiences diverged from our thoughts’ func-
tions, we would quickly lose all feeling of successfully interacting with the world.
Organisational Invariance
Chalmers produces a reductio argument against the claim that the existence and contents
of conscious experience depend in any way on the material constituting our brains. He car-
ries out several thought experiments to demonstrate that a silicon functional isomorph of a
human brain would also produce exactly the same phenomenology. The reductio is as fol-
lows: if silicon brains lacked phenomenology, a complete replacement of neurons in one
person’s brain by silicon would result in ‘absent qualia’ (251–3), gradual replacement would
result in ‘fading qualia’ (253–63) and the installation of a system to switch instantly between
neural and silicon processing would allow for ‘dancing qualia’ (266–74).
Each of these possibilities is found problematic and implausible, thus Chalmers is led to
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