What is conscious experience and do we really need it? By Lisa McLellan
I am going to talk to you about zombies. Not the Dawn of the Dead style zombies – philosophical zombies. Philosophical zombies are indistinguishable from humans like me and you – they can walk, talk, work and blog. The only difference is that they have no conscious experience. Imagine a world identical to ours in every way – but populated with these philosophical zombies instead of us. To an outsider, it would be impossible to tell the difference.
Philosophical zombies are identical to humans. They have the same bodily structures, the same electro-chemical impulses in their brains, responding in the same ways to the same stimuli. For example they have retinas which respond to certain wavelengths of light and transmit this to the visual cortex – so they can distinguish different colours. But while we may have a visual experience of, say, the colour red, they have no more visual experience than a camera.
There has been much controversy about whether philosophical zombies are possible. David Chalmers is one of the main proponents of zombies. He argues that, although they may not be physically possible, philosophical zombies are conceivable – therefore, they are at least logically possible.
conscious as a ghost…
If they are possible, then it seems our conscious experience is not a necessary ingredient for carrying out our lives. After all, there should be no physical or behavioural difference between us and zombies. Chalmers puts forward the view that consciousness is an additional extra – like a ghost, passively emerging from the physical processes of the brain, but never influencing or interacting with them. The view that consciousness has no causal role is known as epiphenomenalism.
If our conscious experiences have no causal effect, then why are we conscious at all? This question is central to the zombie debate.
Why experience at all?
It seems obvious that our conscious experiences have an influence on how we behave. We eat certain foods because they taste good, we like certain music because it sounds good, and we choose particular perfumes because they smell good. It’s possible that zombies could make these judgements solely by identifying the make-up of different foods or sounds or smells – without consciously experiencing tasting, hearing and smelling. But what do you think? If you think we need to consciously experience things, then we must work out how the conscious experiences which emerge from our brain’s activity make us act any differently than a zombie.