Week 6 · Chapter

Chapter 6 — The Mind-Body Problem

Introduction to Philosophy Free sample edition

The module's primary reading · ~40–50 minutes · Objective 4 (compare positions on the mind-body problem, personal identity, and free will, and evaluate them with the thought experiments that test them), with Objective 2 (identify arguments, put them in standard form, judge whether they are valid, sound, or inductively strong, and test claims with counterexamples and thought experiments) and Objective 3 (explain central positions in metaphysics and epistemology — Plato's Forms, rationalism and empiricism, skepticism, and the analysis of knowledge — and evaluate the arguments for them) carried forward · Read it first this week; the lecture, the slide deck, the tutorial, the quiz, and the Philosophy Workshop all build on it.

In plain language

This week asks what a mind is, and how it is connected to your body and your brain. One answer, substance dualism (the view that mind and body are two different kinds of thing), says your mind is not made of matter at all. Another answer, the identity theory (the view that mental states are brain states), says a pain or a thought is a process in the brain. A third answer, functionalism (the view that mental states are defined by what they do), says a mind is a pattern of jobs that a brain, or maybe a machine, could carry out. You test each answer with a famous thought experiment, and your goal is to state each side fairly, not to pick a winner.

Why you already care about this

Someone at a clinic tells a nurse that a healed burn on one hand still stings. The nurse can see the skin, and it looks fine. A brain scan could show which areas are busy while the sting goes on. But could the scan show what the sting feels like from the inside? You know what your own pain feels like in a way that no screen seems to capture.

Now picture a help-desk chatbot that answers your questions about a late package. It is polite, fast, and right. Does it understand you? Or is it matching your words to stored replies, the way a vending machine matches a button to a snack? You have probably wondered about this, maybe while typing to one.

Those two puzzles are the same old question in new clothes. In 1974 the philosopher Thomas Nagel asked what it is like to be a bat. In 1980 John Searle imagined a person locked in a room with rule-books for Chinese symbols. Both were asking what a mind really is, and whether a full physical account of a creature, or a good enough program, would capture it.

By the end of this chapter you will be able to:

state the mind-body problem in one sentence;
state substance dualism, the identity theory, and functionalism in their strongest forms;
explain the problem of interaction and give the dualist's reply;
put Dataset B's argument 2 in standard form and key it for validity only;
explain what Nagel's bat and Jackson's Mary ask, and give a physicalist reply to each;
describe the Turing test in words and say what it does not test;
reconstruct the Chinese room in standard form, judge it valid, and give the systems reply;
show why Dataset B's argument 8 is invalid.

Carry this line with you: what a state does versus what it is like: keep both in view.

Where we are

Already covered: Week 1, What Philosophy Is: Socrates and the Examined Life, gave you the counterexample test. Week 2, Arguments and Thought Experiments, gave you standard form, validity, and the valid and invalid forms. Week 3, Plato: Reality and the Forms, asked how appearance differs from reality. Week 4, Knowledge I: Doubt, Reason, and Experience, found one belief that survives every doubt, that you exist whenever you think. Week 5, Knowledge II: What Knowledge Is, tested a famous definition with a single counterexample.
This week: what a mind is; substance dualism, the identity theory, and functionalism; the problem of interaction; Nagel's bat; the Turing test; Searle's Chinese room; and Jackson's Mary.
How they connect: Weeks 3 to 5 asked what is real and what you can know. This week begins a new unit on mind and self, and turns those questions on the knower: what is the thing that does the knowing?
Where we're going next: Week 7, Personal Identity and Free Will, asks what makes you the same person over time, and whether you are free.

Two tools from earlier weeks do the heavy lifting. From Week 2, you need standard form: premises numbered P1, P2, and P3, the conclusion last, marked C and introduced by "So", and any premise the reconstruction adds marked "(added)". You need valid (the conclusion cannot be false if the premises are true) and invalid (the conclusion could be false even if the premises are true). You also need two forms. Denying the consequent is valid: if P then Q; not Q; so not P. Running the conditional backward is invalid: if P then Q; Q; so P. From Week 5, you need the habit of testing a general claim with one well-chosen case.

1. Name the problem: what is a mind?

Think about the last time you wanted a snack. A wish showed up, and then your legs carried you to the kitchen. The wish seems to be "in your head". Your legs are plainly in the room. How does the first thing make the second thing move?

That is the start of a very old puzzle. Here it is in the course's words.

Mind-body problem — the problem of how mental states, such as pains, thoughts, and wishes, are related to the physical body and brain.
Mental state — any state of mind a creature can be in, such as feeling a pain, believing a claim, or wanting something.

Dataset E, the mind-body positions, pins 3 standard answers. The rest of this chapter states each one the way its best defenders would, then presses it with its strongest objection, then gives a reply.

Dataset E: three standard positions on the mind-body problem, each with its central claim and what presses it
Position	Central claim	Pressed by
Substance dualism	Mind and body are different kinds of thing	The problem of how an immaterial mind moves a body
Identity theory	Mental states are brain states	Nagel's bat (1974); Jackson's Mary (1982)
Functionalism	Mental states are defined by their causal roles	Searle's Chinese room (1980); Jackson's Mary (1982)

Read the table as a map, not as a scoreboard. Every position on it has serious defenders. The course keys no verdict on which one is right.

Misconception check — a problem is not a mystery with no answers. Students often think the mind-body problem means nobody has any idea what a mind is. It is tempting because the word "problem" sounds like a dead end. The cure is to look at the table. There are well-worked answers, each with real support. The problem is that each one also faces a hard objection.

2. State substance dualism, then press it with interaction

Close your eyes and think of the number seven. Now ask: how big is that thought? How much does it weigh? What color is it? The questions sound strange. Thoughts do not seem to have sizes, weights, or colors at all.

That strangeness is where substance dualism starts.

Substance dualism — the view that mind and body are different kinds of thing, so that a mind is not a physical object and is not made of the matter that makes up a body.

Here is the view in its strongest form. Physical things have size, shape, weight, and a place. A thought, a wish, or a pain does not seem to have any of these. You also know your own mind in a special way, from the inside. You can be wrong about your hand, as Week 4's dream argument showed, but you seem to know that you are in pain while you are in it. Week 4's cogito was reached by thinking alone, while every sense was in doubt. A dualist says that inside knowledge is a sign that the mind is something other than the body it lives in.

Now the strongest objection.

Problem of interaction — the objection to substance dualism that asks how a mind that is not physical could cause changes in a physical body, or be changed by it.

Worked example — the wave. You decide to wave at a friend across the street, and your hand goes up.

What the dualist says happened: a mental event, the decision, caused a physical event, the hand moving.
What the objection asks: the decision has no size, no place, and no push. Physical causes we know about work by contact, force, or energy. So how could something with none of these move a hand?
The reply, from the dualist side: a puzzle about how a cause works is not proof that it does not happen. Many causes were known to happen long before anyone could explain how. The link between mind and body may be a basic fact that has no further explanation.

In one plain sentence: substance dualism fits how thoughts seem from the inside, and its hardest test is explaining how a thought could move a hand.

Misconception check — dualism is not the view that the mind does nothing. Students often think a dualist must say the mind is a ghost that floats free of the body. It is tempting because "not physical" sounds like "not connected". The cure is the wave example. The dualist says the mind and body do act on each other. That claim is what the problem of interaction challenges.

3. State physicalism and the identity theory

Think about lightning. For most of human history, people saw a bright flash and heard thunder and had no idea what it was. Then scientists found that lightning is an electrical discharge. Lightning did not turn out to be two things, a flash plus a discharge. It turned out to be one thing, described in two ways.

The identity theory says the mind is like that.

Physicalism — the view that everything that exists is physical, so that minds, too, are made of nothing beyond the physical world.
Identity theory — the physicalist view that mental states are brain states, so that a pain and the brain process that goes with it are one thing described in two ways.

Here is the view in its strongest form. Changes in the mind track changes in the brain very closely. A blow to the head, a drug, or a night without sleep changes how a person thinks and feels. If mental states are brain states, that is exactly what you would expect. The identity theory also has no problem of interaction. A wish to wave is a brain state, and brain states can send signals down nerves to a hand.

Misconception check — "brain states" does not mean "nothing is felt". Students often think the identity theory says pain is not real, or that feelings are an illusion. It is tempting because "it's only the brain" sounds dismissive. The cure is the lightning example. Finding out that lightning is a discharge did not make lightning unreal. The identity theorist says pain is real, and that it is a brain state.

4. Test an argument against the identity theory

Here is an argument from Dataset B, the argument set (illustrative), aimed at the identity theory. Its premises were written for teaching, and the course does not endorse them.

Worked example — Dataset B, argument 2, in standard form. Lay the argument out line by line, then name its form.

P1: If the mind is the brain, then mental states have locations.

P2: Mental states have no locations.

C: So the mind is not the brain.

Name the form. Let P be "the mind is the brain" and Q be "mental states have locations". The pattern is if P then Q; not Q; so not P. That is denying the consequent, from Week 2. Key it: valid. If both premises were true, the conclusion could not be false.

Now the harder question. Is it sound? An identity theorist replies that P2 is false: a pain is located where its brain state is, somewhere inside the skull. A dualist replies that it makes no sense to say a thought is two inches behind your left eye. That disagreement is an open question, so the course keys this argument for validity only.

Misconception check — valid is not the same as settled. Students often think a valid argument against a view has refuted the view. It is tempting because "valid" sounds final. The cure is Week 2's two questions. Valid only means the conclusion would follow if the premises were true. Here, the identity theorist denies P2, so the argument settles nothing until that premise is settled.

5. Ask what it is like to be a bat

Picture a barn at dusk. Bats pour out of the rafters and swerve between the beams without hitting anything. Many bats find their way in the dark by sending out sounds and sensing the echoes. Now try to imagine what that is like for the bat. Not what you would feel hanging upside down, but what the bat feels as the echoes come back.

That is the question in the title of Thomas Nagel's "What Is It Like to Be a Bat?" (The Philosophical Review, 1974). Nagel argues that physical accounts of the mind leave out the subjective character of experience.

Subjective character of experience — what an experience is like for the creature having it, from its own point of view.

Here is the force of the case. Suppose scientists learned every fact about a bat's brain: every cell, every signal, every echo. That list would be written from the outside, in the third person. It seems it would still not tell you what the experience is like from the inside, for the bat. If the identity theory says mental states are brain states, then a full account of the brain should leave nothing out. Nagel's case suggests it leaves out the most personal part.

The reply, from the physicalist side: the case shows a limit of our point of view, not a gap in the world. We cannot take up a bat's perspective, because we do not have a bat's brain. That does not show the bat's experience is something other than a brain process. It shows that knowing about a brain from outside differs from being that brain.

In one plain sentence: Nagel's bat suggests that a physical account may leave out what experience is like from the inside, which presses the identity theory, and the physicalist answers that this is a limit of our viewpoint rather than a non-physical fact.

Misconception check — the case is not about bats being mysterious. Students often think Nagel's point is that bats are strange animals we have not studied enough. It is tempting because the example is so vivid. The cure is to notice the point would hold for any creature, including another person. More study from the outside does not seem to give you the view from the inside.

6. State functionalism: a mind is what it does

Think about the word "goalkeeper". A goalkeeper can be tall or short, young or old, and wear any jersey. What makes someone the goalkeeper is the job: standing in the goal and stopping shots. The job defines the role, not the body that fills it.

Functionalism says mental states are like that.

Functionalism — the view that mental states are defined by their causal roles, by what they do rather than by what they are made of, so that anything playing the right role, brain or machine, could be in the state.
Causal role — the pattern of causes and effects that marks out a mental state for functionalism: what typically brings the state about, and what behavior and other states it typically leads to.

Worked example — pain, defined by its role. Write out pain's causal role in 3 parts.

What typically causes it: bodily damage, such as a burn or a cut.
What it typically causes in the mind: distress, and the belief that something is wrong.
What it typically causes in behavior: the urge to protect the hurt spot, such as pulling a hand back from a stove.

On functionalism, pain is whatever state plays that whole role. In a human, a certain brain process plays it. In an octopus, with a very different nervous system, something else might. In a well-built machine, a pattern in a circuit might. Each of them could be in pain if something in it plays the role.

That is how functionalism answers an objection to the identity theory. If pain is one particular human brain state, then a creature with a different brain could never be in pain. But it seems that creatures with very different brains can share pain. Functionalism lets them.

Misconception check — functionalism is not a claim about brains only. Students often think functionalism is another way of saying "the mind is the brain". It is tempting because, in humans, brains do the work. The cure is the goalkeeper. Functionalism says what matters is the role. A brain is one thing that can fill it. A machine, or a creature built very differently, could fill it too.

7. Describe the Turing test in words

Picture a game played by text messages. You sit at a screen and chat with two hidden partners. One is a person. One is a machine. You can ask anything you like. Your job is to tell which is which.

That is the shape of Alan Turing's imitation game, now called the Turing test, described here in outline.

Turing test — Alan Turing's imitation game, in which a questioner trades typed messages with a hidden machine and a hidden person and tries to tell which is which, as a way to ask whether a machine can think.

Turing proposed it as a way to ask whether a machine can think. The test fits well with functionalism. If a mind is defined by what it does, then a machine that does everything a thinking person does in conversation looks like a strong candidate for thinking.

Here is a caveat worth keeping. The test checks behavior in conversation, and only that. It is not built to check whether a machine feels anything.

Misconception check — the Turing test is not a test of consciousness. Students often think a machine that passes the Turing test has been shown to be conscious. It is tempting because a convincing chat partner feels like someone. The cure is to read the test's design. It checks whether a questioner can tell the machine from a person by its typed replies. Passing it would not, by itself, show that the machine feels anything, which is exactly the question Nagel's bat raised.

8. Step inside the Chinese room

Now the week's thought experiment, the Week 6 case on the course's thought-experiment roster.

John Searle, in "Minds, Brains, and Programs" (Behavioral and Brain Sciences, 1980), describes the Chinese room. A person who knows no Chinese sits in a room full of rule-books for matching Chinese symbols. Questions written in Chinese come in through a slot. The person looks up each string of symbols, follows the rules, and passes out strings that, it turns out, are fluent answers. To the people outside, the room seems to understand Chinese. The person inside understands none of it.

The Chinese room — John Searle's thought experiment of 1980, in which a person who knows no Chinese follows rule-books for matching Chinese symbols and passes out fluent answers, to ask whether following a program is the same as understanding.

The roster gives the case a question: Is following a program the same as understanding? It tests functionalism and machine minds. The rule-books play the part of a computer program. If running the right program were enough for understanding, the person running it should understand. The person does not.

Worked example — the Chinese room in standard form. This is the course's reconstruction of Searle's reasoning (illustrative), written to teach the step. The third premise is one the reconstruction adds, so it is marked.

P1: The person in the room runs a program for answering questions in Chinese.

P2: The person does not understand Chinese.

P3 (added): If running the right program were enough for understanding, anyone who runs it would understand.

C: So running the right program is not enough for understanding.

Now judge it. P1 and P2 together say that someone runs the program without understanding. That denies the consequent of P3, "anyone who runs it would understand". The pattern is if P then Q; not Q; so not P, which is denying the consequent. So the argument is valid: if all three premises are true, C cannot be false.

Now the strongest objection, from the functionalist side.

Systems reply — the functionalist reply to the Chinese room that the person is one part of a larger system of person, rule-books, and room, and that the whole system, not the person alone, understands.

The systems reply denies P3 as Searle needs it. The person is like one part of a machine. A brain understands, though no single brain cell understands anything. In the same way, the whole room might understand Chinese, though the person in it does not. Someone who defends Searle's side answers that you could, in principle, memorize the rule-books and do it all in your head, and you would still not understand a word. The debate goes on from there.

In one plain sentence: the Chinese room suggests that following rules for symbols may not be enough for understanding, which is a challenge to functionalism, and the systems reply answers that understanding may belong to the whole system rather than to the person inside.

Misconception check — the Chinese room is about understanding, not about machines being useless. Students often think the Chinese room shows that machines can never be intelligent. It is tempting because it is the most famous argument against machine minds. The cure is to read the conclusion word for word: running the right program is not enough for understanding. It says nothing about whether a machine can answer well, and the room itself answers very well. Its target is the claim that the program alone gives understanding.

9. Check the help-desk chatbot

Back to the chatbot answering your question about a late package. Suppose it answers in Chinese for a customer who writes in Chinese. Someone reasons like this. The argument is from Dataset B, the argument set (illustrative).

Worked example — Dataset B, argument 8, in standard form. Lay it out, then check the form.

P1: If a machine understands Chinese, it can answer questions in Chinese.

P2: This machine answers questions in Chinese.

C: So it understands Chinese.

Let P be "a machine understands Chinese" and Q be "it can answer questions in Chinese". The pattern is if P then Q; Q; so P. That runs the conditional backward, from the consequent to the antecedent. Key it: invalid.

Here is a counterexample to the form, using Week 2's method: keep the pattern, change the content. "If a person is a chef, they can boil an egg. This person can boil an egg. So this person is a chef." Both premises can be true of a ten-year-old making breakfast, and the conclusion is false. A form that allows true premises with a false conclusion is invalid. So argument 8 gives no support to its conclusion, however well the chatbot answers.

Misconception check — invalid does not mean the conclusion is false. Students often think that because argument 8 is invalid, the chatbot must not understand Chinese. It is tempting because the argument "fails". The cure is Week 2's distinction. An invalid argument fails to support its conclusion. The conclusion might still be true or false; this argument does not tell you which.

10. Meet Mary in her black-and-white room

Picture a scientist named Mary. She knows every physical fact there is to know about color vision: how light of each wavelength strikes the eye, which cells respond, and which signals travel to the brain. But she has lived her whole life in a black-and-white room, and she has never seen a color. One day the door opens, and she sees a red apple.

This case comes from Frank Jackson's "Epiphenomenal Qualia" (The Philosophical Quarterly, 1982). Its question: does Mary learn something new when she first sees red?

Qualia — the felt qualities of experience, such as how red looks or how a sting feels to the one who has it; the word is plural, and its singular is quale.
Mary's room — Frank Jackson's thought experiment of 1982 about Mary, a scientist who knows every physical fact about color vision but has lived in a black-and-white room, which asks whether she learns something new when she first sees red.

Here is the force of the case. Many people feel sure that Mary learns something: what red looks like. But she already knew every physical fact. If she learns a new fact, then some fact about experience is not a physical fact. That would press the identity theory, which says mental states are brain states, and functionalism alike, since a full account of every causal role is also a physical account.

Worked example — the timeline of the week's papers. Line up the three dated papers.

Nagel's bat: 1974.
Searle's Chinese room: 1980. The gap: 1980 − 1974 = 6 years.
Jackson's Mary: 1982. The gap: 1982 − 1980 = 2 years.
The two gaps together: 6 + 2 = 8 years.
A check from the two ends: 1982 − 1974 = 8 years.

In words: both ways of counting give 8, so the week's 3 papers span 8 years.

The reply, from the physicalist side: Mary gains a new ability, to recognize and imagine red, or a new way of knowing a fact she already knew, not a new fact. Compare knowing a city from a map with walking its streets. You learn something when you walk them, but you may not learn any new fact about where the streets are.

Here is an honesty note. Both the case and the reply are still argued over, and the course keys no verdict on whether Mary learns a new fact.

Misconception check — Mary is not a case about ignorance. Students often think the point is that Mary did not study hard enough. It is tempting because "she learns something" sounds like "she missed something in class". The cure is the setup. By stipulation, Mary knows every physical fact. The case asks whether that could still leave something out.

11. Weigh the three positions side by side

You now have all three answers in hand. The fair way to compare them is the course's way: each view in its strongest form, its strongest objection, and a reply from its own side.

Substance dualism, the identity theory, and functionalism compared: central claim, strongest objection, and a reply from each side
Position	Central claim	Strongest objection	Reply from its side
Substance dualism	Mind and body are different kinds of thing.	The problem of interaction: how could a mind that is not physical move a body?	Not knowing how a cause works is no proof that it does not happen; the link may be basic.
Identity theory	Mental states are brain states.	Nagel's bat and Jackson's Mary: a full physical account seems to leave out what experience is like.	The cases show a limit of our point of view, or a new way of knowing an old fact, not a non-physical fact.
Functionalism	Mental states are defined by their causal roles.	Searle's Chinese room: following a program may not be enough for understanding; Mary presses it too.	The systems reply: the whole system, not one part of it, is what understands.

Worked example — counting the pressed-by column. Count the entries in Dataset E's pressed-by column.

Substance dualism: 1 (the problem of interaction).
Identity theory: 2 (Nagel's bat and Jackson's Mary).
Functionalism: 2 (Searle's Chinese room and Jackson's Mary).
In all: 1 + 2 + 2 = 5 entries.

In words: there are 5 entries, but only 4 different challenges, because Mary is counted twice. She presses both physicalist answers.

Where do the three sides disagree, in one plain sentence? They disagree about whether the mind is a separate kind of thing, a particular kind of brain process, or any system that plays the right roles, and each answer has a case that presses it.

A limitation to keep in view: this week compares only three positions, and the course keys no verdict on which one is right. Your job is to state each one so well that its own defenders would sign it.

Pause and think, choosing one of these two options:

(a) Pick the objection in the table you find strongest, and write two sentences on how its target position's reply could be made stronger.
(b) Pick the reply in the table you find weakest, and write two sentences on what its critics would say back.

Misconception check — an objection is not a knockout. Students often think the position with the most entries in the pressed-by column must be the weakest. It is tempting because counting feels objective. The cure is to notice that the count says how many famous cases a view faces, not how good the replies are. Every position here has a serious reply, and that is what an open question looks like.

Key terms

Mind-body problem — The problem of how mental states, such as pains, thoughts, and wishes, are related to the physical body and brain. (first used: 1. Name the problem: what is a mind?)
Mental state — Any state of mind a creature can be in, such as feeling a pain, believing a claim, or wanting something. (first used: 1. Name the problem: what is a mind?)
Substance dualism — The view that mind and body are different kinds of thing, so that a mind is not a physical object and is not made of the matter that makes up a body. (first used: 2. State substance dualism, then press it with interaction)
Problem of interaction — The objection to substance dualism that asks how a mind that is not physical could cause changes in a physical body, or be changed by it. (first used: 2. State substance dualism, then press it with interaction)
Physicalism — The view that everything that exists is physical, so that minds, too, are made of nothing beyond the physical world. (first used: 3. State physicalism and the identity theory)
Identity theory — The physicalist view that mental states are brain states, so that a pain and the brain process that goes with it are one thing described in two ways. (first used: 3. State physicalism and the identity theory)
Subjective character of experience — What an experience is like for the creature having it, from its own point of view; Thomas Nagel argued in 1974 that physical accounts of the mind leave it out. (first used: 5. Ask what it is like to be a bat)
Functionalism — The view that mental states are defined by their causal roles, by what they do rather than by what they are made of, so that anything playing the right role, brain or machine, could be in the state. (first used: 6. State functionalism: a mind is what it does)
Causal role — The pattern of causes and effects that marks out a mental state for functionalism: what typically brings the state about, and what behavior and other states it typically leads to. (first used: 6. State functionalism: a mind is what it does)
Turing test — Alan Turing's imitation game, in which a questioner trades typed messages with a hidden machine and a hidden person and tries to tell which is which, as a way to ask whether a machine can think; it tests conversation, not consciousness. (first used: 7. Describe the Turing test in words)
The Chinese room — John Searle's thought experiment of 1980, in which a person who knows no Chinese follows rule-books for matching Chinese symbols and passes out fluent answers, to ask whether following a program is the same as understanding. (first used: 8. Step inside the Chinese room)
Systems reply — The functionalist reply to the Chinese room that the person is one part of a larger system of person, rule-books, and room, and that the whole system, not the person alone, understands. (first used: 8. Step inside the Chinese room)
Qualia — The felt qualities of experience, such as how red looks or how a sting feels to the one who has it; the word is plural, and its singular is quale. (first used: 10. Meet Mary in her black-and-white room)
Mary's room — Frank Jackson's thought experiment of 1982 about Mary, a scientist who knows every physical fact about color vision but has lived in a black-and-white room, which asks whether she learns something new when she first sees red. (first used: 10. Meet Mary in her black-and-white room)

Summary

The mind-body problem asks how mental states are related to the physical body and brain.
Substance dualism: mind and body are different kinds of thing; its hardest test is the problem of interaction.
The identity theory: mental states are brain states, as lightning is an electrical discharge.
Dataset B's argument 2 is valid by denying the consequent and is never keyed for soundness.
Nagel's bat (1974) asks whether a physical account leaves out what experience is like.
Functionalism: mental states are defined by their causal roles, so it is not a claim about brains only.
The Turing test checks conversation, not consciousness.
The Chinese room (Searle, 1980) asks whether following a program is the same as understanding; the systems reply is the functionalist answer.
Dataset B's argument 8 is invalid, because it runs the conditional backward.
Jackson's Mary (1982) presses both physicalist answers; the reply says she gains an ability or a new way of knowing an old fact.
No position is keyed as correct; each gets its strongest form, its strongest objection, and a reply.

Check your understanding

Work these before looking at the answers — they are ungraded, and the answers (with reasoning) are at the bottom of the page.

A shopper says, "If this smart thermostat feels cold, it turns on the heat. It turned on the heat. So it feels cold." Put the argument in standard form, name its form, and say whether it is valid.
Sort each claim under the position it expresses: (a) "Fear is whatever state is caused by a threat and causes a racing heart and the urge to run." (b) "My fear is a certain pattern of activity in my brain, nothing more." (c) "My fear belongs to something that is not physical at all."
A classmate writes, "Searle's Chinese room proves that no machine will ever be intelligent." Explain what is wrong with that sentence, and rewrite it so it states the case's conclusion fairly.
A translation app at a train station chats with travelers so well that, in a short trial, most of them cannot tell it from a human helper. Does that show the app is conscious? Explain in two or three sentences.

Answers (worked reasoning — read after attempting)

P1: If this smart thermostat feels cold, it turns on the heat. P2: It turned on the heat. C: So it feels cold. P is "the thermostat feels cold" and Q is "it turns on the heat". The pattern is if P then Q; Q; so P, which runs the conditional backward. That form is invalid: a thermostat could turn on the heat because a timer told it to, or because a sensor's number dropped, with nothing felt at all. True premises would not guarantee the conclusion.
(a) Functionalism: fear is defined by its causal role, by what causes it and what it causes. (b) The identity theory: fear is a brain state. (c) Substance dualism: the mind is a different kind of thing from the body.
The case's conclusion is narrower. It says that running the right program is not enough, on its own, for understanding. It does not say machines cannot answer well or behave intelligently; the room answers very well. A fair version: "Searle's Chinese room is meant to show that following a program, by itself, may not be enough for understanding."
No, not by itself. The trial is a version of the Turing test, which checks whether people can tell the machine from a person by its replies. That is a test of conversation. Whether the app feels anything is a separate question, the one Nagel's bat raises.

Next up in this module: the Readings & Resources page, the lecture tutorial, the practice set, the quiz, the discussion, and the assignment. Next week, Locke's memory theory and the ship of Theseus test what makes you the same person over time.

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