Summary And Discussions Ch-23

Chapter 23 Functionalism

Chapter Outline 1. Functionalism’s Negative Thesis: What’s Wrong with the Identity Theory? 2. Multiple Realizability 3. Could a Computer Have Psychological Characteristics? 4. Multiple Realizability within the Class of Living Things 5. Functionalism’s Positive Thesis 6. Sensations 7. Summary

The Mind/Brain Identity Theory, our topic in the previous chapter, applies to the mind/body problem the general thesis that everything is material. Minds aren’t made of an immaterial substance; rather, people have minds and mental characteristics by virtue of the fact that they have brains that possess various sorts of physical structure.

In the 1960s and 1970s, several philosophers—preeminently, Hilary Putnam (in “The Nature of Mental States” in H. Putnam, Mind, Language, and Reality,Cambridge University Press, 1975) and Jerry Fodor (in Psychological Explanation, Random House, 1968)— developed a criticism of the identity theory. They espoused a point of view that came to be called “functionalism.” Although functionalism does not reject materialism, it does reject one important part of the identity theory. Functionalism has two parts—one negative, the other positive. The negative part describes what psychological states are not. This is the functionalist critique of the identity theory. The positive part advances a proposal about what psychological states are. I’ll take these two ideas in order.

Functionalism’s Negative Thesis: What’s Wrong with the Identity Theory? To begin with, I need to draw a commonsense distinction. Suppose someone says to you, looking at your clothing, “We own the same shirt.” What might this mean? There are two choices. One is that you and this person own the same kind of shirt. The other is that the very shirt on your back is jointly owned by the two of you.

Let’s introduce some terminology to mark this distinction. Unique physical objects are called tokens. Kinds (or properties) are called types. The unique physical object that you are

now wearing is a token of many types. It is a token of the type shirt; it is also a token of the type blue, and a token of the type clothing. To say that a single token is a token of many types is merely to say that a single object has many properties.

Conversely, a given type may have zero, one, or many tokens that fall under it. Unicorn is a type of animal that has no instances; there are no tokens of that type. Golden mountain is a type of geological object, one that happens to have no exemplars. You can see just from this pair of examples that two types (properties) may apply to exactly the same tokens and still be distinct types. Being a unicorn isn’t the same property as being a golden mountain, even though the set of unicorns has precisely the same members as the set of golden mountains.

How does the type/token distinction apply to the mind/body problem? The identity theory has two parts. It makes a claim about psychological tokens and also a claim about psychological types. The former category—of psychological tokens—includes the following: Descartes’ mind, the pain I felt in my foot last Thursday, Jones’s thinking to herself today that lemons are yellow. Each of these is a token, and the identity theory says that each is identical with some physical token.

In addition, there are psychological types (properties); the identity theory makes a claim about these as well. For example, there is the property of having a mind, the property of feeling pain, the property of believing that lemons are yellow, and so on. Note that these types each have numerous tokens falling under them. Each type, therefore, describes something that various tokens have in common. The identity theory says that each of these psychological types (properties) is identical with some physical property or other.

Multiple Realizability Functionalism rejects what the identity theory says about psychological types. Functionalists hold that psychological properties are not identical with physical properties. Instead, functionalists argue that psychological types are multiply realizable. I’ll explain this idea with an example.

Consider a type that isn’t psychological—the property of being a mousetrap. Each token mousetrap is a physical object. But think of all the different ways there are to build a mousetrap. Some are made of wood and wire and are loaded with cheese. Others are made of plastic and catch mice by injecting them with curare. Still others are made of a team of philosophers, who stalk around armed with inverted wastepaper baskets. There are many, perhaps endlessly many, ways to build a mousetrap.

Is there a single physical characteristic that all mousetraps have in common, and which non-mousetraps lack? This seems highly dubious. Each token mousetrap is a physical thing, but the property of being a mousetrap (the type) doesn’t seem to be a physical property at all.

How does this analogy bear on the plausibility of the Mind/Brain Identity Theory? There is more than one (physical) way to build a mousetrap. The analogy is that there may be many physical ways to build a creature that has a mind, and more than one way for a being with a mind to have this or that psychological property.

The Birthday Fallacy, Again The Birthday Fallacy, introduced in Chapter 4, is the mistake you make if you confuse the following two statements: • Everyone has a birthday. • There is a single day on which everyone was born. The first is true; the second false. It’s a fallacy to think that the first entails the second. You’d be making the same mistake if you confused the following two statements:

• Each mousetrap has physical properties that allow it to catch mice. • There is a single set of physical properties that all mousetraps have in common that

allows them to catch mice. The first is true; the second false. How can the Birthday Fallacy be used to describe functionalism’s criticism of the identity theory?

Could a Computer Have Psychological Characteristics? Consider computers. It isn’t very plausible to regard very simple computers as having beliefs and desires. My desk calculator no more “knows” facts about simple arithmetic than my stove “knows” recipes for making soup. Rather, human beings use these devices to do arithmetic or to make soup. A desk calculator, in this respect, is like paper and pencil. It facilitates our calculations, but doesn’t itself engage in mental activity.

Don’t be misled by the fact that we sometimes use mentalistic terms to describe simple computers. For example, we talk about computer “memory.” However, I don’t think my home computer literally remembers anything. This is just a metaphor. If I write some thoughts on a piece of paper and those scribbles are not erased, it is true that the piece of paper has “retained” the inscriptions I placed there. But the piece of paper does not remember anything. In this respect, I think a simple computer is just like a piece of paper.

Very simple machines do not have minds or mental states. But let’s now use our imaginations and think about what the future may bring. Could there be computers that have mental states? Could computers be built that perceive—see and hear, for example? Could computers be built that remember? Could a computer reason? Could a computer be built that has wants and needs and preferences? Functionalists regard these as very real possibilities. Perhaps current computers can’t do these things, and perhaps computer scientists at times exaggerate how close they are to making computers with these abilities.

But take seriously for a moment the possibility that computers eventually will be built that have one or more of these mental abilities.

This possibility has serious implications for the identity theory. These computers, let’s suppose, won’t be made of protein. Perhaps they will be made of silicon chips. There seems to be no reason to expect that these thinking machines must be physically very much like the brains we have. Just as there are many physical ways to build a mousetrap, so there seem to be many physical ways to have a mind and to have particular mental states.

Multiple Realizability within the Class of Living Things We don’t need to consider the future of computer science to see the point of the idea of multiple realizability. Organisms other than human beings have psychological states. Some can perceive and remember and feel pain, even if they aren’t capable of all the complex thoughts and feelings that human beings can experience. Is it reasonable to suppose that these psychological states in other species must be based on precisely the same physical structures that are present in human beings?

Even within the human species, there may be variation in the physical structures used to encode this or that mental state. Indeed, even within a single human being, there may be many ways that the brain can encode a single piece of information. When you believe that lemons are yellow at two different times, maybe the brain structure that encodes your belief at the one time differs from the brain structure that encodes it at the other time.

This is functionalism’s criticism of the identity theory. A given mental type—believing that lemons are yellow, wanting a drink of water, feeling pain—is not identical with any single physical type. The reason the identity theory is false is that psychological types have multiple physical realizations. This point might be formulated slightly sarcastically by saying that functionalism accuses the identity theory of being a “chauvinistic doctrine.” (This quip is due to Ned Block, “Troubles with Functionalism,” in W. Savage [ed.], Perception and Cognition, University of Minnesota Press, 1978.) Identity theorists say that a computer or another species must be like us physically if it is to have a mind and mental characteristics. Functionalism regards this as implausibly restrictive. This, then, is the negative thesis that functionalism advances. Mental properties are not identical with physical properties. Notice that this rejection of type-identity is consistent with accepting token-identity. Perhaps being a mousetrap isn’t a physical property, but each mousetrap is a physical thing. Perhaps believing that lemons are yellow isn’t a physical property, but my present state of believing that lemons are yellow might still be identical with a physical state that my brain occupies. Functionalism rejects the identity theory’s thesis of type- identity, not its thesis of token-identity.

The identity theory is a version of materialism. So is functionalism. The identity theory denies that minds are made of an immaterial substance; it denies that disembodied spirits exist. Functionalism agrees. The following table shows how these two theories are related to each other, and also to dualism:

Types and Tokens: How Dualism, the Identity Theory, and Functionalism are Related

Dualism

Are all mental types identical with physical types? No

Are all mental tokens identical with physical tokens? No

Functionalism is an intermediate position; it is conceptually “in between” dualism and the identity theory.

Functionalism’s Positive Thesis So much for the negative thesis. What positive account does functionalism provide concerning what the mind and its properties are like? The name functionalismsuggests what this positive account is. Let’s return to the property of being a mousetrap. This property, I’ve argued, is not identical with any single physical property. What, then, makes something a mousetrap? What do the mousetraps have in common that makes them different from the non-mousetraps? A mousetrap is any device that functions to turn a free mouse into a caught one. Mousetraps are things that play a particular causal role. Any device that produces certain effects in certain circumstances counts as a mousetrap, regardless of what physical materials it is made of or how it is physically constructed. The property of being a mousetrap is a functional property.

What does it mean, then, to claim that psychological properties are “functional” properties? Let’s consider a psychological state X that has the following characteristics:

• When someone believes that there is water in a cup in front of her and the individual is in state X, she drinks from the cup.

• When someone believes that a well contains water and she is in state X, then the individual will draw water from the well and drink it.

Each of these two statements is a conditional; it describes what an agent will do if the agent has a particular belief and is in state X. Can you guess from these two conditionals what state X is? A reasonable conjecture is that X is the state of wanting to drink water. Of course,

there is more to this desire than what these two conditionals describe. Functionalism maintains that these conditionals, and others like them, describe what it is to have a particular desire. Any state that plays the right causal role will be the desire to drink water. The physical composition of the state does not matter. Psychological states are to be understood in terms of their causal relations to behavior and to other mental states. This example concerning state X suggests the following functionalist proposal for understanding what it is for an agent to have a desire:

• S wants proposition P to be true if and only if, if S’s beliefs are true, then S will cause P to become true.

Notice that this proposal describes desire as a state that plays a particular causal role: When added to beliefs, desires produce actions of certain sorts. As plausible as this suggestion might be at first glance, there are problems. First, people don’t always get what they want when their beliefs are true. A pitcher may want to strike out a batter and may have true beliefs about how to achieve this, but still the pitcher may fail. The second objection is that people sometimes cause propositions to come true that they don’t want to come true. When I drink from the cup, I cause my moustache to get damp, but this isn’t something I want. So there is a defect in the functionalist proposal just stated for understanding what desire is. Perhaps it can be repaired. Maybe there is something right about the idea that mental states are to be understood in terms of their causal connections with behavior and with other mental states.

Sensations The kind of difficulty we have been considering is especially prominent when we shift our attention from beliefs and desires to sensations. Consider what a functionalist says about the nature of pain, for example. When people are in pain, they are inclined to say “Ouch!” They are inclined to withdraw their bodies from the stimulus they think is causing the pain. And being in pain diminishes a person’s attention span and has other psychological effects as well. Suppose I exhaustively described the causes and the effects of being in pain. These would involve the relationship of being in pain to external stimuli, to behavior, and to other psychological states. (Some of these I just mentioned.) It is sometimes suggested that this functionalist account of pain leaves out the most important fact about pain—the fact that pain hurts. A state may play the functional role of pain and still not be a pain state, or so this objection asserts. If this is right, then functionalism will fail as an account of the nature of pain.

I won’t try to answer this question of whether functionalism is adequate. Perhaps there are some psychological phenomena that functionalism cannot adequately characterize. Maybe sensations (like pain) are counterexamples to functionalism. Even if this is true, however, there may be other psychological states for which functionalism is adequate; perhaps belief and desire can be understood along functionalist lines. This is now a controversial issue in philosophy.

Summary I have argued that dualism, logical behaviorism, and the Mind/Brain Identity Theory are each inadequate. I think there is nothing wrong with mentalism—the view that beliefs and desires are inner causes of outward behavior. Behavior provides evidence about what an agent’s mental states are, but behavior does not definewhat it is to be in a given mental state. To make sense of mentalism, we need not think that an agent’s mind is made of some strange immaterial substance (as dualism maintains). Individuals have minds in virtue of the physical organization of their bodies. This, however, does not require that all the individuals who possess some psychological characteristic (like feeling pain or believing that lemons are yellow) have some single physical characteristic in common. My conclusion is that functionalism’s negative thesis is correct; it is plausible to hold that psychological states are multiply realizable. As for the positive thesis that functionalism advances, it remains to be seen whether an adequate functionalist account of different mental states can be developed.

In the rest of this part of the book, I’ll explore two other philosophical problems about the mind. If human beings act as they do because of what they think and want, and if what they think and want is caused by things outside of themselves, how can human beings have free will? This problem is addressed in Chapters24– 26. After that, I’ll consider the problem of psychological egoism. If human beings act on the basis of what they think and want, doesn’t it follow that people always act selfishly—that they try to satisfy their own wants and never care, ultimately, about the welfare of others?

Review Questions 1. I return home from a furniture store and report to my family, “They’re selling our

sofa.” I look at the plate of food in front of my son and say, “That is what I ate for lunch.” How does the type/token distinction help identify an ambiguity that is present in each of these two remarks?

2. What does it mean to say that a psychological property (a type) is multiply realizable?

3. Functionalists criticize the Mind/Brain Identity Theory for being “chauvinistic.” What does this mean?

4. How is it possible to reject the identity theory without thinking that there are immaterial minds (disembodied spirits)?

5. Functionalists try to characterize what it is to have a psychological property (like feeling pain or believing that Washington is the capital of the United States) by describing that property’s “causal role.” What does that mean?

Problems for Further Thought 1. The fact that two types apply to exactly the same tokens isn’t enough to ensure that

they are identical. For example, being a unicorn and being a golden mountain are different types (properties), even though they apply to exactly the same objects (namely, to no objects at all). Can the same point be made with respect to types that are exemplified? Can two types be different, even though they apply to the same (nonempty) set of objects? Describe an example of this sort.

2. In Chapter 6, I discussed the concept of fitness that is used in evolutionary theory. What would it mean to say that fitness is multiply realizable? Is it plausible to claim that fitness has this characteristic?

3. Here is the inverted spectrum problem: You have a particular characteristic sensation when you look at red things and a quite different sensation when you look at green things. Is it possible that someone has precisely the reverse arrangement? This individual would have a red sensation when he looks at green things and a green sensation when he looks at red things. His behavior, including his use of language, would be precisely the same as yours. For example, he would apply the term “red” to fire engines and the term “green” to grasshoppers. If spectrum inversion is possible, what consequences does this have for functionalism’s positive thesis about the nature of mental states?