AS Helen Phillips’s article in this issue shows (see “Outer limits of the brain”), the brain is a marvel. Even in the most ordinary of heads, it performs miracles of complexity every second. Equally marvellous is how much we have come to know about brains, though – as always with the growth of knowledge – we have also learned how much more we need to learn.
The great mystery remains, however: how do the intricate, superfast, vastly complex interactions of the brain’s billions of neurons through trillions of synapses give rise to mind? There are many familiar ways of describing this puzzle, but the simplest is to say that physical occurrences in the brain have physical properties – a position in space, a duration in time, a measurable intensity, as well as the involvement of a specifiable set of physiological structures. In contrast, thoughts (about sub-prime mortgages, say, or the political situation in Bulgaria) do not: they do not have a weight, or a colour, or a scent, or any other physical property.
This was once taken to be a reason for thinking that mind and body are separate and wholly different things, creating the larger mystery of how the two interact. Now hardly anyone seriously subscribes to such a view. The mystery is, instead, about how brain activity secretes the rich technicolor phenomena of consciousness, the tangled hidden world of unconscious mentation, and the enduring patterns of character and memory that make individuals unique.
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“Understanding minds involves more than understanding brains alone”
According to one influential school of thought, some of the ways we think about minds have to go beyond our investigations of what is inside our heads to include the physical and social environment surrounding our heads. This idea is prompted by the thought that what we know when we understand a concept has to involve a connection between a brain event and something in the world.
Here is an obvious example: to understand the concept of a , and to be able to distinguish between flowers and other things – trees and buildings, say – the relevant physiological occurrences inside the head have to stand in a determinate relationship with flowers and non-flowers outside the head. This relationship, again obviously, is empirical: an actual perceptual encounter between the head’s owner and flowers (or at least pictures of flowers) must have taken place at some point.
But a less obvious aspect of having a concept of flowers is that whenever we think or talk of flowers, the relationship between what is happening inside our heads and flowers outside our heads has to remain in some form, in order for our discourse to be about flowers rather than some other thing. Nothing mysterious or magical is implied by this; it just means that to explain the thought of a flower as distinct from a thought of anything else, reference to flowers out there in the world is unavoidable.
The notion that thought is thus essentially connected to the outside world is intended to illustrate the more general idea that “mind” is not describable in terms of brain activity alone. Instead, it must be understood as a relationship between that activity and the external social and physical environment. Philosophers give the name “” to thoughts that can only be properly described in terms of their thinkers’ relations to the environment. Some even argue that there can be no such thing as “narrow content” – that is, thoughts that are specifiable independently of their thinkers’ environments and just in terms of what is going on inside the skull.
If it is right that all content is broad content, then the implications are very great. It means that understanding minds involves much more than understanding brains alone. It involves understanding language, society and history too.
