The mind/ body problem is as old as philosophy itself. Usually, people fall into one of two camps here – materialism (also known as physicalism) or dualism. Materialists believe that there is essentially one kind of thing in the world – matter. As such, everything – including our thoughts, feelings, and conscious experience in general – can be reduced to no more than the function of neurons firing in our brain (or whatever science tells us happens in there). Dualists, on the other hand, believe in the existence two fundamental ‘substances’ – matter and mind. Mind, they argue, is non-physical. Today, the vast majority of philosophers advocate some form of materialism and support for dualism is, sadly, waning.
René Descartes was one of the leading proponents of dualism. In his Meditations he famously stated that what we are, essentially, is thinking things. As such, mind is distinct from body. There are, as you might expect, several problems with this view. Firstly, dualism just simply doesn’t fit with the modern scientific view of the universe. For example, how can it be that something non-physical (the mind) can interact with something physical (the body) and vice-versa? This is known as the mind-body problem and still troubles philosophers today. In effect, whenever I decide to move my arm, and then move it, it would amount to something rather like telekinesis. It is for reasons such as this that materialists have lampooned the idea of ‘the ghost in the machine’ (Gilbert Ryle).
One way to avoid these issues, then, is to adopt a monist approach. Monism, unlike, dualism, claims that there is only one type of substance in the world, either mental or physical. George Berkeley most famously took the idealist path, claiming that reality consists of nothing more than minds and their ideas. [Samuel Johnson’s famous rejection of Berkeley’s thesis involved him kicking a rock and exclaiming ‘I refute it thus’.] Materialism, on the other hand, fits neatly with our modern science. It captures the fact that the universe, as we know it, (including our brains and bodies) is made up of matter. What’s more, science can tell us a great deal about the brain and how it operates. Neuroscientists can measure the brain activity that accompanies our conscious experience and can point to examples of brain damage which limit or alter this experience. Meanwhile, people working on artificial intelligence are making vast amounts of progress towards building machines that can ‘think’ (we will consider John Searle’s famous ‘Chinese Room’ rejection of the possibility of ‘thinking’ machines in class). All in all, there are many reasons to opt for materialism; however, there are also some unfortunate consequences.
For one, if we are just complex material machines (physical objects in a physical universe) then the laws of physics – including the law of causality – apply to us as much as anything else. This entails that human free will is just an illusion – rather our actions must be determined by antecedent causes which are themselves determined likewise. As such, perhaps we are all puppets dangling on the strings of determinism – the problem of free will. [We will cover this in more detail later elsewhere but it’s probably worth noting that the problem of free will doesn’t go away if we accept dualism – it just changes.]
Furthermore, there is something very different about our mental life (consciousness) that distinguishes it from the rest of the physical universe. That is, our conscious experience has aboutness (or intentionality) – it is about (directed towards) other parts of the universe. In addition, consciousness, it seems, cannot be adequately described by any scientific account. Even if we knew exactly what was going on in our brains and could describe to the smallest detail our neural activity when we, for example, feel pain – this would still not tell us what it is like to feel pain. This idea is captured brilliantly by Frank Jackson’s ‘Mary’s Room’ thought experiment:
Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white television monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like ‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal cords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’. […] What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not?
Jackson goes on to argue that there will be something else that Mary comes to know about colour after leaving her room – namely, she will know what-it-is-like to see colour. This ineffable quality is known as qualia – the what-it-is-like-to-have-ness of our conscious mental states. This is the subject of Thomas Nagel’s excellent article, ‘What is it like to be a bat?’.
Imagine that one has webbing on one’s arms, which enables one to fly around at dusk and dawn catching insects in one’s mouth; that one has very poor vision, and perceives the surrounding world by a system of reflected high-frequency sound signals; and that one spends the day hanging upside down by one’s feet in an attic. In so far as I can imagine this (which is not very far), it tells me only what it would be like for me to behave as a bat behaves. But that is not the question. I want to know what it is like for a bat to be a bat.
All of this leads neatly to the final issue of personal identity – the question of what is it for a particular person to persist over time and, therefore, what it is that makes us what we are.