- seCtIon FoUR: eVoLUtIon
thought – for that, res cogitans or thinking-stuff was needed (Chapter 1). Among
those who rejected his dualism was Gottfried von Leibniz, best known for his
work on calculus and his philosophy that all matter consists of simple nonmaterial
substances, which he called little minds, or monads. This meant that he rejected
materialism, and he justified this with his famous allegory of the mill (1714/1965).
Imagine a machine whose construction enabled it to think, feel, and perceive.
Imagine, then, that the machine were enlarged while retaining the same pro-
portions, so that we could go inside it, like entering a windmill. Inside we would
find only pieces working upon one another and never anything to explain the
perception. From this he concluded that to explain perception, we must look to a
simple substance rather than to the workings of a machine, which can never have
the unity that consciousness does.
Leibniz’s thought experiment can be applied directly to the human brain. Imag-
ine making the neurons bigger and bigger so that we could go inside. What
would we see but synapses and chemicals working upon one another? Leibniz
also argued that the ‘I’ could not be found in a mill. With this thought experi-
ment he faced, long before neurons and synapses had ever been heard of, the
same questions we face now. How can a machine feel as though it is, or has, a
conscious self?
Another of Descartes’s critics took the opposite tack and scandalised the world
with his infamous book L’Homme Machine (Machine Man, or Man–Machine, 1748).
Julien Offray de la Mettrie was a pleasure-loving French philosopher and physi-
cian who rejected Descartes’s break between man and the soulless animals, and
classified humans as living machines. His materialist and irreligious views pro-
voked outcry, especially since they led him to a morality based on rejecting guilt
and seeking pleasure, and he was forced to flee France, first to the Netherlands
and then to Berlin.
The idea that we are machines has never seemed comfortable; but now that we
understand so much more biology and psychology, the question is not so much
‘Am I a machine?’ but ‘What kind of machine am I?’, and, for our purposes here,
‘Where do “I” fit in?’ and ‘Where does consciousness fit in?’
There are two ways to seek answers. We can start with the biology and try to
understand how natural systems work, or we can build artificial systems and see
how far they can match human abilities. As Stevan Harnad (2007) describes it, we
can reverse-engineer the brain to see how it works, or we can forward-engineer a
brain by building something that can do what brains do.
In consciousness studies, the two endeavours are converging. From the natural
direction, science has successively explained more and more of the mechanisms
of perception, learning, memory, and thinking, and in so doing has only ampli-
fied the ancient open question about consciousness. That is, when all these abil-
ities have been fully explained, will consciousness be accounted for too, or still
be left out?
From the artificial direction, better and better machines have been developed,
leading to the obvious question of whether they are conscious already, or could
be one day. If machines could do all the things we do, just as well as we do them,
would they be conscious? How could we tell? Would they really be conscious, or
just zombies simulating consciousness? Would they really understand what they‘It’s the way our
machine is provisioned
that makes us lively or
brave’
(de la Mettrie, 1748/2015,
trans. Bennett, p. 5)