When we talk about zombies, we often think about zombies portrayed in films and fiction, e.g., the walking-dead brain-eating zombies that we see in horror movies. People in philosophy have been talking about “philosophical zombies” for the past few decades. What is the difference between these? Why have philosophers been so interested in zombies? In this entry I discuss why it has been relevant for philosophers to talk about zombies and how the discussion applies to pain.
Let’s start by clarifying what philosophers have in mind when they discuss zombies:
Zombies in philosophy are imaginary creatures designed to illuminate problems about consciousness and its relation to the physical world. Unlike those in films or witchcraft, they are exactly like us in all physical respects but without conscious experiences: by definition there is ‘nothing it is like’ to be a zombie. Yet zombies behave just like us, and some even spend a lot of time discussing consciousness. (Kirk, 2003)
In contrast to philosophical zombies, the fictional zombies that we often have in mind may have conscious states. They may consciously experience hunger and a certain conscious satisfaction while they eat delicious brains, for instance. This is a very important difference: the type of zombies that are relevant for philosophers are identical to us in everything except for the fact that they lack consciousness, that they are “empty inside”.
How could you recognize a philosophical zombie then? In fact, you couldn’t. It would be impossible to distinguish ourselves from our zombie twins: they would behave and could do all the same things as us and they would have the same physical constitution, including brains like ours and nervous systems identical to our own. However, they would not have any type of conscious experience. When they drink and eat, there is no conscious experience of taste, and when they cut or harm themselves, there is no conscious experience of pain.
After all, if philosophical zombies are just imaginary, how does the discussion about these zombies have an influence on our understanding of consciousness? Why should we care about these zombies?
To answer to this, there are few important things to mention. First, I’ll say something about conceivability and possibility. Many philosophers think that if something is conceivable, then that something is logically possible. Another way of putting this is that if you can conceive something, that thing could exist. If, for example, you can conceive of a ladder that goes to the moon, even if such thing does not actually exist, it could, it is not impossible. In contrast, the fact that we cannot conceive a polygon with four sides and only three angles, a square circle, or two things added to two things making five things shows that such things are impossible and could not exist.
Second, we need to say something about identity. Many people also think that if two things are identical, if they are actually the same thing, then it is logically impossible to for one to exist without the other existing. For example, if we accept that Clark Kent and Superman are identical, then it would be impossible for Clark Kent to exist without Superman existing too. If it were possible for one to exist without the other, then that would show that they are not actually identical.
So, if we accept that 1) everything that we can conceive could also exist, 2) if two things are the same, then one cannot exist without the other, and 3) that philosophical zombies are conceivable, then we can get two interesting conclusions. First, that philosophical zombies could exist (since we can conceive of them, and everything we can conceive, could exist). Second and most important, the mere possibility of zombies now allows us to conclude that conscious experience isn’t identical to the functioning of any physical mechanisms (since if zombies are possible and have all the same functional and physical mechanisms but no consciousness, then having all the same functionality and no consciousness is possible, which means functionality and consciousness are not identical).
The possibility of zombies is problematic if we think that consciousness is identical to the functioning of physical mechanisms. The possibility of philosophical zombies shows that consciousness and the physical mechanisms in our bodies are not identical, since it is possible to have such states and have no consciousness.
This is the relevance of the discussion of zombies for the understanding of consciousness: the possibility of zombies raises problems for the idea that we can ever fully explain what consciousness is by a functional description of the processes that take place in our bodies. Many scientific studies use precisely this methodology, that is, they try to explain what consciousness is by explaining the different physical mechanisms and functions; for example, many scientific studies try to explain what conscious experiences are by accounting for what happens in the brain and the nervous system.
Let’s now exemplify all this with pain.
Imagine that a neuroscientist scans your brain while you are having a conscious pain experience. The neuroscientist could have a very detailed knowledge of the way in which the different areas of your brain light up in the scanner. The neuroscientist could do the same to your zombie twin, and in both cases the data would be exactly the same. This would show that the scientific knowledge that we get about the processes in the body is not knowledge of the conscious experience of pain. In the zombie case, we would know about the physical processes, which would be identical to those in humans, yet we would know nothing about their conscious experiences—since they don’t have any. Knowing what happens in the brain while we have conscious pains does not fully explain them, given that they are not identical; they are not identical because, as it is shown in the zombie example, we can conceive one without the other.
As it is happens with many philosophical discussions, not everybody agrees. Some argue, for instance, that zombies are not really possible and that explaining the functional process is all there is to explain about consciousness. Philosophers who think that zombies are not possible would deny, for instance, that a creature could be in all the same physical states and exhibit all the same behaviour as someone consciously experiencing pain, but not be consciously experiencing anything.
What do you think? Do you think philosophical zombies are possible? Can you imagine them?
Kirk, R., “Zombies”, The Stanford Encyclopedia of Philosophy (Summer 2015 Edition), Edward N. Zalta (ed.), URL = http://plato.stanford.edu/archives/sum2015/entries/zombies/
Kirk, R., (1974), ‘Zombies v. Materialists’, Proceedings of the Aristotelian Society, 48 (Supplementary): 135–152.
Chalmers, D., (1996), “The conscious mind: in a search of a fundamental theory”, New York ; Oxford : Oxford University Press.