Philosophy

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LECTURE: Naturalistic theories of intentionality

Several theories have been proposed for dealing with the problem that intentionality poses for materialism. They are often referred to as “naturalistic” theories of intentionality – theories that try to show that intentionality is just one feature of the natural world alongside others, rather than something immaterial or non-physical. We’ll focus here on what are probably the two most influential approaches: causal theories and “biosemantic” theories.

Causal theories of intentionality

What is it that makes a brain process into a thought with intentionality or meaning? The answer given by causal theories is that it has to do with a cause and effect relation between the brain process and the world outside the brain. There are many defenders of causal theories, one of the most prominent of whom is Jerry Fodor (1935-2017). Here he is:

Rebel with a cause

The basic idea is that a brain process B will represent some state of affairs A if B is caused by A. For example, brain process B will count as the thought that “The cat is on the mat” if it is caused by the presence of a cat on a mat. But as Fodor emphasizes, much more needs to be said. For sometimes a person might think that “The cat is on the mat” even if there’s no cat there, but rather (say) a dog that isn’t seen clearly; and sometimes a cat might really be there but the person doesn’t think “The cat is on the mat,” because (for example) it isn’t seen clearly. So, a causal relation between A and B isn’t enough. It has to be the right kind of causal relation.

In particular, the relation has to be strong enough that B is a reliable indicator of the presence of A. Several stock examples are often used to illustrate the idea. Think of the way that smoke is caused by fire in such a way that the presence of smoke is a reliable indicator of the presence of fire; or the way that measles causes spots to appear on the face in such a way that the spots are a reliable indicator of measles; or the way that the age of a tree causes it to have a certain number of rings, so that the number of tree rings is a reliable indicator of the age of the tree.

If some brain process B is regularly triggered by a state of affairs of type A so that B is a reliable indicator of A, then in that case, the causal theory says, B will represent A. It will count as a thought about A.

Ready to cause a thought

Asymmetric dependence

But it turns out that even that is not enough. Fodor thinks we need to say more, in light of certain objections that might be raised against the causal theory. For example, suppose Grandma has a cat and that a brain process B in her brain is regularly triggered by the presence of the cat on the mat, so that B is a reliable indicator of the presence of the cat. So far so good.

But now suppose also that a neighborhood dog sometimes comes in through the cat door and is about the same size and color of the cat. Suppose Grandma’s vision is not good and she just assumes it is the cat. And suppose the dog comes in so frequently that it triggers Grandma’s though no less frequently than the cat does.

The problem is this. If the causal theory is right, then Grandma’s brain process B should represent or be about whatever reliably triggers or causes it. But two things reliably cause it: either the presence of the cat or the presence of the dog. So, if the causal theory is right, it seems that the content of her thought should be “The cat is on the mat OR the dog is on the mat.” It should be a disjunctive thought (where a disjunction is an either-or statement). But it’s not. She only ever thinks that it’s a cat, and has no idea that there is ever a dog around. This is called the disjunction problem for the causal theory.

The cat is on the mat OR the dog is on the mat

Fodor tries to solve this problem as follows. Yes, the presence of the dog regularly triggers Grandma’s brain process B. But that’s only because she already had a cat which regularly triggered that brain process. If Grandma had never had the cat, there is no guarantee that, seeing the dog, she’d think “The cat is on the mat.” Maybe, in that case, she’d realize it might be a dog. At the same time, if the dog had never come into the picture, she would still have the thought “The cat is on the mat” when the cat triggered brain process B.

So, the cause and effect relation between brain process B and the dog is dependent on or parasitic on the cause and effect relation between brain process B and the cat. But the causal relation between B and the cat is not dependent on the relation between B and the dog. There is an asymmetry here. So, to get around the “disjunction problem,” we can formulate the causal theory to say that a brain process B will represent A if it is a reliable indicator of A and the relation between B and A does not have an asymmetric dependence on some other cause and effect relation.

Problems for the causal theory

As you can see, spelling out the theory in detail gets technical. But however it is spelled out, the theory faces several problems. Here are some of them:

1. Non-existent objects, future events, etc.

The causal theory says that a brain process B will count as a thought about A if B is caused in the right way by A. But we can have thoughts about things that don’t exist, such as the Easter bunny, and about events that haven’t happened yet, like the sun going supernova. Since these things don’t exist, they can’t be what causes any process B in our brains (since non-existent things can’t cause anything). But in that case, how could we think about them, if the causal theory were correct?

2. The misrepresentation problem

Sometimes we systematically misrepresent the things that cause our thoughts. For example, suppose that over the course of several days Grandma thinks she sees a snake on the lawn at the other end of her back yard, but that in fact it is just a garden hose. The hose is what reliably triggers her brain process B, the cause and effect relation between the hose and B is not asymmetrically dependent on some other causal relation operating at the time, but it still isn’t the hose that she is thinking about. She always just thinks it’s a snake. If B will be about whatever causes it, then how could we ever misrepresent things in such a way?

Eek! A snake!

3. Derived and as-if intentionality rather than intrinsic intentionality

Why would the fact that A causes a brain process B be enough to make B a thought about A in the first place? Go back to the stock examples of reliable indication. Fire causes smoke, but smoke doesn’t think about fire, because smoke doesn’t think about anything. Measles cause spots on the face, but the spots don’t think about measles, because spots don’t think about anything. And tree rings don’t think about the age of a tree even though they are caused by it. So, how does the fact that a brain event B is caused by A enough to make it a thought about A?

The most the stock examples give us is derived intentionality or even just as-if intentionality (to recall Searle’s distinction from last time). For example, it’s as if smoke was about fire, or we can regard smoke as a sign of fire as a matter of convention. But these are not examples of the intrinsic intentionality that is definitive of thought.

Biosemantic theories

An alternative to the causal theory is a “biosemantic theory” of intentionality (a label arrived at by combining “biology” and “semantics”). On this sort of view, a brain process B will represent some thing A by virtue of its biological function (with the notion of biological function analyzed in terms of Darwin’s account of evolution by natural selection).

A prominent defender of this sort of approach is the contemporary philosopher Ruth Millikan. Here she is:

Bridging philosophy and biology

The idea here is that the function of an organ is to be understood in terms of the reason it was favored by natural selection. For example, the heart was favored by natural selection because it pumped the blood. So, pumping blood can be said to be the function of the heart. Of course, the heart does other things too (such as making a thumping sound) but these are not the reason why natural selection favored it. That is why pumping blood, specifically (rather than making a thumping sound), would count as the function of the heart.

Now, go back to the example of Grandma’s thinking that there’s a snake in the back yard. We can understand why a brain process of type B represents snakes (rather than garden hoses) if we think of it as having been hardwired into us by natural selection as a kind of snake-avoidance mechanism. That is its biological function. And it is biological function, on this view, that gives a brain process the specific meaning it has. The biosemantic theory is, accordingly, claimed to have a way of dealing with the “misrepresentation problem” that gives it an advantage over the causal theory.

Problems for biosemantic theories

But this sort of theory also faces several well-known objections. Here are some of them:

1. Complex concepts

Suppose that we allow, for the sake of argument, that the biosemantic theory can explain why a brain process B might count as a thought that deploys concepts like snake, water, food, etc. Those concepts have clear survival value insofar as they allow us better to avoid predators, to get hold of crucial resources, etc. But many of our thoughts and concepts have no evident survival value. For example, possessing the concept of iambic pentameter, or of cold fusion, or of a carburetor, or any of thousands of other concepts, seems to have no survival value in the relevant sense. Indeed, these concepts didn’t even exist at the time our ancestors evolved. So it is hard to see how we can explain why a brain process would count as a thought about any of these things in terms of natural selection.

2. The “swampman” objection

The biosemantic theory seems to imply that a creature could count as having meaningful thoughts or intentionality only if it arose out of a process of evolution by natural selection. But that doesn’t seem to be correct. Suppose that through some random and improbable event, a creature that was an exact particle-for-particle duplicate of an ordinary human being arose in a swamp somewhere. Perhaps a bolt of lightning struck an area of the swamp at a spot where nuclear and chemical waste had been congealing, at the exact moment when a random fluctuation in the structure of matter was occurring at the quantum level (or whatever).

If such a creature was an exact physical duplicate of a human being, then it seems that a materialist would have to say that it would behave exactly like a normal human being, including saying and thinking the sorts of things that a normal human being would. But it would be doing so even though it arose as a result of a freak accident rather than by natural selection. And in that case, it seems that the biosemantic theory is wrong to claim that intentionality requires having arisen via natural selection.

Swamp Thing. Not exactly an exact duplicate.

3. How would this explain intrinsic intentionality?

There is also the problem that the biosemantic theory, like the causal theory, doesn’t actually appear to be sufficient to explain intentionality even if the other objections could be answered. Lots of organs have functions and were favored by natural selection, but nevertheless aren’t associated with the intentionality of thought. For example, the heart was favored because it pumps blood, but no one claims that anything in the heart counts as a thought about pumping blood. The teeth were selected to allow us to chew food, but no one would say that the teeth are thinking about chewing food. Hearts and teeth don’t have minds or think about anything.

So, how would the fact that a certain brain process B was favored by natural selection show that it counts as a thought (about snakes, or water, or anything else)?

Here are some optional YouTube videos on our subject:

Thomas Polger on Naturalizing Intentionality, Part 2:

https://www.youtube.com/watch?v=g3IeGEHemxo

Introduction to Intentionality: Materialist Solutions:

https://www.youtube.com/watch?v=9RXEwgQQhro

Thinking about Thoughts: The Problem of Intentionality:

https://www.youtube.com/watch?v=fgXIjqCdP8w