Kim Sterelny: "The Imagery Debate"
We have encountered the view that the brain/mind works by manipulating representations.
One variety of that view is that the representations that are manipulated in the brain/mind are quasi-linguistic.
Let me reprise the arguments for mantaining that these representations must be linguistic.
1. If they weren't, there would be no logical relations between them.
Let me explain.
A. You can only conduct deductions between propositions if you have as your raw material propositions that are structured. Deductions depend on propositions having something but not everything in common.
Consider the following propositions:
(1) Every animal is a living thing
(2) Every human being is an animal
(3) Every human being is a living thing
If this is a valid argument, what makes it valid?
It can only be valid if there are terms in common between the propositions.
'animal' is common to (1) and (2).
'living thing' is common to (1) and (3)
'human being' is common to (2) and (3).
If no terms were in common, you couldn't have a valid argument, could you?
(1) Every animal is a living thing.
(2) Every human being is a philanthropist.
(3) Every rhododendron is a thing of beauty.
These are representations, and they are structured. It's just that they don't happen to have the right structure for any inferences to be possible between these three representations on their own. . They don't have logical relations with each other.
So that even with propositions, which are structured, you still can't have inferences unless the structures relate in certain ways. Logicians, you could say, try and set out the structural relationships that have to be there for inferences to be valid.
They would set out the following set of structures for example as supporting a valid inference:
(1) Every A is a B
(2) Every C is an A
(3) Every C is an B
So you have to have propositions that are appropriately structured in order to have valid inferences.
But we can go on to make the point that without any structure at all inference as we know it would not be possible.
Propositions are structured, so I can't give any examples of structureless propositions.
But just think of proper names on their own:
(1) Walter
(2) Elizabeth
(3) Chloe
(3) The Empire State Building
These don't have structure. Can inferences hold between them?
Summary of Argument 0:
For there to be inference as we know it, there need to be propositions; and it is the structure of propositions which makes inference possible.
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We have talked about inference, and the dependence of inference on propositions.
I have used repeatedly this phrase 'linguistically structured'. A proposition is linguistically structured.
It is structured.
And the structure is linguistic. It has the same structure as a sentence.
A proposition is a paradigm example of a representation.
The proposition 'My brother lives in London' represents my brother's living in London.
A proposition is a linguistically structured representation.
So the point so far is that inference depends on representations that are linguistically structured.
But let us think now not of propositions but of machinery and what sort of representations that can handle, and what sort of things it can do with them.
Machinery can do maths.
You can represent numbers on a machine, and you can get the machine to add numbers and subtract them. You can do this of course with simple clock-like mechanisms. You don't have to think of electronics.
Numbers are not propositions
But machines can also do logic - that is to say manipulate representations of propositions according to the rules of logic.
So the first thing is: machines can represent propositions.
It would be strained to speak of there being propositions in the machine. What there are in the machine are thousands of electronic switches, and it is sequences of these which represent propositions.
You can make a bank of switches stand for
100; or
'the rhododendron is a beautiful genus.'
You can do this just as you can make a pattern on a piece of cotton stand for Brazil, as in a flag.
There is no mystery particularly. You are making one thing - a bank of switches - stand for something - a proposition.
So it would be wrong to speak of the representations in the machine as propositions. They are banks of switches standing for propositions.
We can call them quasi-propositions. They are essentially like propositions, but they are actually not propositions.
So I have explained what a 'quasi- propostion' is.
When the machine manipulates quasi-propositions according to the rules of logic, is it conducting 'inferences'?
You could say they are not exactly inferences, but they are like inferences. Call them 'quasi-inferences'.
So I've (sort of) explained what a 'quasi-inference' is.
I said what I would do was to reprise the arguments for the thesis that the representations that are manipulated in the brain/mind must be quasi-linguistic.
The first argument I said was this: if the representations manipulated by the brain were not structured linguistically or quasi-linguistically, there could be no logical relations between them.
If the representations in the brain were not linguistically or quasi-linguistically structure, no inferences or quasi-inferences could be performed on them.
What kind of a drawback would that be?
It appears to be inconsistent with the theory that the brain is a control device on the pattern of a von Neumann computer.
Performing inferences or quasi inferences seem to be at the heart of this conception.
The idea is that the brain takes in sense data, builds a data bank, works out what it must get the body to do to respond to environmental challenges. A lion approaches and the brain is suppose
to take in the fact, take account of what it knows about lions and what they do, and reach the conclusion that evasive action is called for.
(I'm saying the idea is that the brain must be doing this: nothing to do with what goes on in consciousess.)
Another example:
The snake moves at random, finds food, returns every evening to the same spot where it regularly finds food. Von Neumann theorists say this behaviour is a result of the brain processing information, and processing information involves making inferences or quasi- inferences.
So the argument is: unless the representations in the brain were structured quasi-linguistically, you could not think of the brain as a control device on the model of the von Neumann computer.
Call this Argument 0
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Argument 1
If representations in the brain are unstructured, no two of them would have any element in common. This suggests an enormous number of completely independent representations in the brain. The representation of 'the lion charging' would be completely different from the representation of 'charging animals are dangerous'.
Argument 2
Systematicity of thought
Argument 3
Productivity of thought
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Pick up here on
the second half of the
The Churchland's article.
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It is said that we know that some of the representations in the brain/mind are not structured linguistically: mental images.
There are said to be two accounts of how mental images represent. One is that represent in the way in which pictures represent. This is pictorialism.
The other is that they represent in the way in which propositions represent. This is descriptivism.
Block describes experimental results which are interpreted as supporting pictorialism.