This is a draft 28-Jul-05 of Part II of The Emotion Machine by Marvin Minsky. Please send comments to firstname.lastname@example.org.
§1-1. Falling in Love............................................................................................................................................ 1
§1-2. The Sea Of Mental Mysteries..................................................................................................................... 4
§1-3. Moods and Emotions.................................................................................................................................. 6
§1-4. Infant Emotions.......................................................................................................................................... 7
§1-5. Seeing a Mind as a Cloud of Resources..................................................................................................... 9
§1-6. Adult Emotions......................................................................................................................................... 13
§1-7. Emotion Cascades..................................................................................................................................... 15
§1-8. Questions.................................................................................................................................................. 16
"Oh, life is a glorious
cycle of song,
A medley of extemporanea;
And love is a thing that can never go wrong;
And I am Marie of Roumania.”— Dorothy Parker
Many people find it absurd to conceive of a person as being a kind of machine —so we often hear statements like this:
Citizen: Of course machines can do useful things. We can make them add up huge columns of numbers or assemble cars in factories. But nothing made of mechanical stuff could ever have genuine feelings like love.
No one finds it surprising these days when we make machines that do logical things, because logic is based on clear, simple rules of the sorts that computers can easily use. But Love by its nature, some people would say, cannot and ought not be explained in such ways! Listen to Pablo Neruda:
" ...love has to be so,
involving and general,
particular and terrifying,
honoured and yet in mourning,
flowering like the stars,
and measureless as a kiss.” — from ‘Extravagaria’
What is Love, and how does it work? Is this something we want to understand, or should we see such poems as hints that we don’t really care to probe into it? Hear our friend Charles attempt to describe his latest infatuation.
I’ve just fallen in love with a wonderful person. I scarcely can think about anything else. My sweetheart is unbelievably perfect—of indescribable beauty, flawless character, and incredible intelligence. There is nothing I would not do for her.
On the surface such statements seem positive; they’re all composed of superlatives. But note that there’s something strange about this: most of those phrases of positive praise use syllables like ‘un–’, ‘–less’, and ‘in-‘un-’, ‘-less’, and ‘in-’—which show that they really are negative statements describing the person who’s saying them!
------ (I can't figure out what attracts me to her.)
I scarcely can think of anything else.
------ (Most of my mind has stopped working.)
Unbelievably Perfect. Incredible.
------ (No sensible person believes such things.)
She has a Flawless Character.
------(I've abandoned my critical faculties.)
There is nothing I would not do for her.
------ (I've forsaken most of my usual goals.)
Our friend sees all this as positive. It makes him feel happy and more productive, and relieves his dejection and loneliness. But what if most of those pleasant effects were caused by attempts to defend him from thinking about what his girlfriend says:
Celia: “Oh Charles—a woman needs certain things. She needs to be loved, wanted, cherished, sought after, wooed, flattered, cosseted, pampered. She needs sympathy, affection, devotion, understanding, tenderness, infatuation, adulation, idolatry—that isn't much to ask, is it Charles?” 
Thus love can make us disregard most defects and deficiencies, and make us deal with blemishes as though they were embellishments—even when, as Shakespeare said, we still may be aware of them:
WHEN my love swears that she is made of
I do believe her, though I know she lies,
That she might think me some untutor'd youth,
Unskilful in the world's false forgeries.
Thus vainly thinking that she thinks me young,
Although I know my years be past the best,
I smiling credit her false-speaking tongue,
Outfacing faults in love with love's ill rest.
But wherefore says my love that she is young?
And wherefore say not I that I am old?
O, love's best habit is a soothing tongue,
And age, in love, loves not to have years told.
Therefore I'll lie with love, and love with me,
Since that our faults in love thus smother'd be.”
We are equally apt to deceive ourselves, not only in our personal lives but also when dealing with abstract ideas. There, too, we frequently find ways to keep inconsistent or discordant beliefs. Listen to Richard Feynman’s words:
“That was the beginning and the idea seemed so obvious to me that I fell deeply in love with it. And, like falling in love with a woman, it is only possible if you don't know too much about her, so you cannot see her faults. The faults will become apparent later, but after the love is strong enough to hold you to her. So, I was held to this theory, in spite of all the difficulties, by my youthful enthusiasm.”— 1966 Nobel Prize lecture.
What does a lover actually love? That word ought to cover the one you adore—but if your goal is just to extend the pleasure that comes when doubts get suppressed, then you’re only in love with Love itself.
Citizen: Your description of ‘love’ in the section above spoke only of transient infatuation—of sexual lust and extravagant passion. It left out most of what we usually mean by that word—such as loyalty and tenderness, or attachment, trust, and companionship.
Indeed, once those short-lived attractions fade, they sometimes go on to be replaced by more enduring relationships, in which we exchange our own interests for those of the persons to whom we’re attached:
Love, n. That disposition or state of feeling with regard to a person which (arising from recognition of attractive qualities, from instincts of natural relationship, or from sympathy) manifests itself in solicitude for the welfare of the object, and usually also in delight in his or her presence and desire for his or her approval; warm affection, attachment. —Oxford English Dictionary
Yet even this conception of love is too narrow to cover enough, because Love is a kind of suitcase-like word, which includes other kinds of attachments like these:
The love of a parent for a child.
A child's affection for parents and friends.
The bonds that make lifelong companionships.
Attachments of members to groups or their leaders.
We also apply that same word ‘love’ to our fondness for objects, events, and beliefs.
A convert's adherence to doctrine or
A patriot's allegiance to country or nation.
A scientist's passion for finding new truths.
A mathematician's devotion to proofs.
We thus apply 'love' to our likings for things that we treasure, desire, or fill us with pleasure. We apply it to bonds that are sudden and brief, but also to those that increase through the years. Some occupy just small parts of our minds, while others pervade our entire lives.
But why do we pack such dissimilar things into a single suitcase-like word? It’s the same for our other ‘emotional’ terms; each of them abbreviates a diverse collection of mental states. Thus Anger may change our ways to perceive, so that innocent gestures get turned into threats, and it alters the ways that we react, to lead us to face the dangers we sense. Fear too affects the ways we react, but makes us retreat from dangerous things (as well as from ones that might please us too much).
Returning to the meanings of ‘Love’, one thing seems common to all those conditions: each leads us to think in different ways:
When a person you know has fallen in love, it's almost as though someone new has emerged—a person who thinks in other ways, with altered goals and priorities. It's almost as though a switch had been thrown, and a different program has started to run.
This book is mainly filled with ideas about what could happen inside our brains to cause such changes in how we think.
Every now and then we dwell on questions about how we manage ourselves.
Why do I waste so much of my time?
What determines whom I’m attracted to?
Why do I have such strange fantasies?
Why do I find mathematics so hard?
Why am I afraid of heights and crowds?
What makes me addicted to exercise?
But we can’t hope to understand such things without adequate answers to questions like these:
How do our minds build new ideas?
What are the bases for our beliefs?
How do we learn from experience?
How do we manage to reason and think?
In short, we’ll need to get better ideas about the processes that we call thinking. But whenever we start to think about this, we encounter yet more mysteries.
What is the nature of Consciousness?
What are feelings and how do they work? How do our brains Imagine things?
How do our bodies relate to our minds?
What forms our values, goals, and ideals?
Now, everyone knows how Anger feels––or Pleasure, Sorrow, Joy, and Grief —yet as Alexander Pope suggests in his Essay on Man, we still know almost nothing about how those processes actually work.
“Could he, whose rules the rapid comet
Describe or fix one movement of his mind?
Who saw its fires here rise, and there descend,
Explain his own beginning, or his end?”
How did we manage to find out so much about atoms and oceans and planets and stars—yet so little about the mechanics of minds? Thus Newton discovered just three simple laws that described the motions of all sorts of objects, Maxwell uncovered just four more that explained all electro-magnetic events—and Einstein then reduced all those laws into yet smaller formulas. All this came from the success of those physicists’ quest: to find simple explanations for things that, at first, seemed extremely complex.
Then, why did the sciences of the mind make less progress in those same three centuries? I suspect that this was largely because most psychologists mimicked those physicists, by looking for equally compact solutions to questions about mental processes. However, that strategy never found small sets of laws that accounted for, in substantial detail, any large realms of human thought. So this book will embark on the opposite quest: to find more complex ways to depict mental events that seem simple at first!
This policy may seem absurd to scientists that have been trained to believe such statements as, “One should never adopt hypotheses that make more assumptions than they need.” But it is worse to do the opposite—as when we use ‘psychology words’ that mainly hide what they try to describe. Thus, every phrase in the sentence below conceals its subject’s complexities:
You ‘look at an object and see what it is.
For, ‘look at’ suppresses your questions about the systems that choose how you move your eyes. Then, ‘object’ diverts you from asking about your visual systems partition a scene into various patches of color and texture—and then assign them to different ‘things.’ And, ‘see what it is’ sidesteps all the questions you could ask about how that sight might be related to other things that you’ve seen in the past.
It is much the same for the commonsense words that we usually use to talk about what our own minds do, as when one makes a statement like, “I think I understood what you said.” For perhaps the most extreme example of this is how we use words like Me and You—because we all grow up with this fairy-tale:
We each are constantly being controlled by powerful creatures inside our minds, who do our feeling and thinking for us, and make our important decisions for us. We call these our Selves or Identities—and believe that they always remain the same, no matter how we may otherwise change.
This “Single-Self” concept serves us well in our everyday social affairs. But it hinders our efforts to think about what minds are and how they work—because, when we ask about what Selves actually do, we get the same answer to every such question:
Your Self sees the world by using your senses. Then it stores what it learns in your memory. It originates all your desires and goals—and then solves all your problems for you, by exploiting your ‘intelligence.’
A Self controlling its Person’s Mind
What attracts us to this queer idea, that we don’t make any decisions ourselves but just delegate them to something else? Here are a few kinds of reasons why a mind might entertain such a fiction:
Child Psychologist: Among the first things you learn to recognize are the persons in your environment. In your next stage, you should assume that you are also a person, too. But perhaps it is easier to conclude that there is a person inside of you.
Therapist: Although it’s a legend, it makes life more pleasant—by keeping us from seeing how much we’re controlled by conflicting, unconscious goals.
Pragmatist: That image makes us efficient, whereas better ideas might slow us down. It would take too long for our hard-working minds to understand everything all the time.
However, although the Single-Self concept has practical uses, it does not help us to understand ourselves—because it does not provide us with smaller parts we could use to build theories of what we are. When you think of yourself as a single thing, that gives you no clues about issues like these:
What determines the subjects I think about?
How do I choose what next to do?
How can I solve this difficult problem?
Instead, the Single-Self concept only offers useless answers like these:
My Self selects what to think about.
My Self decides what I should do next.
I should try to make Myself get to work.
Whenever we wonder about our minds, the simpler are the questions we ask, the harder it seems to find answers to them. When you are asked about some difficult task like, “How could a person build a house,” you might answer almost instantly, “Make a foundation and then build walls and a roof.” However, one can scarcely imagine what to say about seemingly simpler questions like these:
How do you recognize things that you
How do you comprehend what a word means?
What makes you like pleasure more than pain?
Of course, none of those questions are simple at all. The process of ‘seeing’ a car or a chair uses hundreds of different parts of your brain, each of which does some quite difficult jobs. Then why don’t we sense that complexity? That’s because many processes that are most vital to us have evolved to work inside parts of the brain that have come to function so ‘quietly’ that the rest of our minds have no access to them. This could be why we find it so hard to explain many things we find so easy to do.
In Chapter §9, we’ll come back to that Self—and argue that this, too, is a very large and complicated structure.
Whenever you think about your “Self,” you are switching among a huge network of models, each of which tries to represent some particular aspects of your mind—to answer some questions about yourself.
If one should seek to name each particular one of them of which the human heart is the seat, each race of men having found names for some shade of feeling which other races have left undiscriminated … all sorts of groupings would be possible, according as we chose this character or that as a basis. The only question would be, does this grouping or that suit our purpose best? — William James, in Principles of Psychology.
Sometimes you find yourself in a state where everything seems cheerful and bright. Other times (although nothing has changed) everything seems dreary and dark, and your friends describe you as being depressed. Why do we have such states of mind—or moods, or feelings, or dispositions—and what causes all their strange effects? Here are some of the phrases we find when dictionaries define ‘emotion’.
The subjective experience of
a strong feeling.
A state of mental agitation or disturbance.
A mental reaction involving the state of one’s body.
A subjective rather than conscious affection.
The part of consciousness that involves feeling.
A non-rational aspect of reasoning.
If you didn’t yet know what emotions are, you certainly wouldn’t learn much from this. What is subjective supposed to mean? How are emotions involved with feelings? Must every emotion involve a disturbance? And what could a conscious affection be?
Why do so many such questions arise when we try to define what ‘emotion’ means? That’s because ‘emotion’ is one of those suitcase-words that covers too wide a range of things. Here are just a few of the hundreds of terms that we use for discussing our mental conditions:
Admiration, Affection, Aggression, Agony, Alarm, Ambition, Amusement, Anger, Anguish, Anxiety, Apathy, Assurance, Attraction, Aversion, Awe, Bliss, Boldness, Boredom, Confidence, Confusion, Craving, Credulity, Curiosity, Dejection, Delight, Depression, Derision, Desire, Detest, Disgust, Dismay, Distrust, Doubt, etc.
Whenever you change your mental state, you might try to use those emotion-words to try to describe your new condition—but usually each such word or phrase refers to too wide a range of states. So, many researchers have spent their lives at trying to classify our states of mind, by stuffing familiar words like these into such classes as humors, emotions, tempers, and moods. But should we call anguish a feeling or mood? Is sorrow a type of agitation? There’s no way to settle the use of such terms because, as William James observed above, different traditions make different distinctions, and may not describe the same states of mind because different people have different ideas. How many readers can claim to know precisely how each of those feelings feels?
Grieving for a lost child,
Fearing that nations will never live in peace,
Rejoicing in an election victory,
Excited anticipation of a loved one’s arrival,
Terror as your car loses control at high speed,
Joy at watching a child at play,
Panic at being in an enclosed space.
Although it is hard to define words like feeling and fearing, that’s rarely a problem in everyday life because our friends usually know what we mean. However, attempts to make such terms more precise have hindered psychologists more than they've helped to make theories about how human minds work. So this chapter will take a different approach, and think of minds as composed of much smaller parts or processes. This will lead to some new and useful ways to imagine what feeling and thinking might be.
Infants, when suffering even slight pain, moderate hunger, or discomfort, utter violent and prolonged screams. Whilst thus screaming their eyes are firmly closed, so that the skin round them is wrinkled, and the forehead contracted into a frown. The mouth is widely opened with the lips retracted in a peculiar manner, which causes it to assume a squarish form; the gums or teeth being more or less exposed. —Charles Darwin, in The Emotions of Animals
One moment your baby seems perfectly well, but then come some restless motions of limbs. Next you see a few catches of breath—and in the next moment, the air fills with screams. Is baby hungry, sleepy, or wet? Whatever it is, those cries compel you to find some action that will help. It may take you some time to discover the trouble, but once you find the remedy, things quickly return to normality. However, if you’re not used to dealing with infants, those sudden switches in mood can upset you; when your friends cry, you can ask them what's wrong—but talking to infants is fruitless because "no one is home" to communicate with.
Of course, I do not mean to suggest that infants don’t have ‘personalities.’ You can usually sense, quite soon after birth, that a particular baby reacts more quickly, or seems more patient or irritable, or even more inquisitive. Some of those traits may change with time, but others persist through the rest of that life. Nevertheless, we still need to ask, how could an infant change so much between one moment and the next? The Single-Self model cannot explain how suddenly an infant can switch from contentment or calmness to anger or rage.
To make a more plausible model for this, imagine that someone has asked you to build an artificial animal. You could start by making a list of goals that your animal-robot needs to achieve. It might need to find sources of water and food. It might need defenses against attacks—and against extremes of temperature. It might even need ways to attract helpful friends. Then once you have assembled that list, you could tell your engineers to meet each such need by building a separate “instinct-machine.
Then, how could we build those instinct-machines? Each of them needs three kinds of resources: some ways to recognize situations, some knowledge about how to react to these, and some muscles or motors to execute actions.
What could be in that central knowledge box? Let's begin with the simplest case: suppose that we already know, in advance, all the situations our robot will face. Then all we need is a catalog of simple, two-part "If–>Do" rules—where each If describes one of those situations—and its Do describes which action to take. Let’s call this a “Rule-Based Reaction-Machine.”
If temperature wrong,
Adjust it to normal.
If you need some food, Get something to eat.
If you’re facing a threat, Select some defense.
If an active sexual drive, Search for a mate.
Many If–>Do rules like these are born into each species of animals. For example, every infant is born with ways to maintain its body temperature: when too hot, it can pant, sweat, stretch out, and vasodilate, when too cold, it can retract its limbs or curl up, shiver, vasoconstrict, or otherwise generate more heat. [See §6-1.2.] Later in life we learn to use actions that change the external world.
If your room is too hot, Open a window.
If too much sunlight, Pull down the shade.
If you are too cold, Turn on a heater.
If you are too cold, Put on more clothing.
This idea of a set of "If–>Do rules” portrays a mind as nothing more than a bundle of separate reaction-machines. Yet although this concept may seem too simplistic, in his masterful book, The Study of Instinct, Nikolaas Tinbergen showed that such schemes could be remarkably good for describing some things that animals do. He also proposed some important ideas about what might turn those specialists on and off, how they accomplish their various tasks, and what happens when some of those methods fail.
Nevertheless, no structure like this could ever support the intricate feelings and thoughts of adults—or even of infants. The rest of this book will try to describe systems that work more like human minds.
Today, there are many thinkers who claim that all the things that human minds do result from processes in our brains—and that brains, in turn, are just complex machines. However, other thinkers still insist that there is no way that machines could have the mysterious things we call feelings.
Citizen: A machines can just do what it’s programmed to do, and then does it without any thinking or feeling. No machine can get tired or bored or have any kind of emotion at all. It cannot care when something goes wrong and, even when it gets things right, it feels no sense of pleasure or pride, or delight in those accomplishments.
Vitalist: That’s because machines have no spirits or souls, and no wishes, ambitions, desires, or goals. That’s why a machine will just stop when it’s stuck—whereas a person will struggle to get something done. Surely this must be because people are made of different stuff; we are alive and machines are not.
In older times, those were plausible views because we had no good ideas about how biological systems could do what they do. Living things seemed completely different from machines before we developed modern instruments. But then we developed new instruments—and new concepts of physics and chemistry—that showed that even the simplest living cells are composed of hundreds of kinds of machinery. Then, in the 20th century, we discovered a really astonishing fact: that the ‘stuff’ that a machine is made of can be arranged so that its properties have virtually no effect upon the way in which that machine behaves!
Thus, to build the parts of any machine, we can use any substance that’s strong and stable enough: all that matters is what each separate part does, and how those parts are connected up. For example, we can make different computers that do the same things, either by using the latest electrical chips— or by using wood, string and paper clips—by arranging their parts so that, seen from outside, each of them does the same processes. [See §§Universal Machines.]
This relates to those questions about how machines could have emotions or feelings. In earlier times, it seemed to us that emotions and feelings were basically different from physical things—because we had no good ways to imagine how there could be anything in between. However, today we have many advanced ideas about how machines can support complex processes—and the rest of this book will show many ways to think of emotions and feelings as processes.
This view transforms our old questions into new and less mysterious ones like, “What kinds of processes do emotions involve,” and, “How could machines embody those processes?” For then we can make progress by asking about how such a brain could support such processes—and today we know that every brain contains a great many different parts, each of which does certain specialized jobs. Some can recognize various patterns, others can supervise various actions, yet others can formulate goals or plans, and some can engage large bodies of knowledge. This suggests a way to envision a mind (or a brain) as made of hundreds or thousands of different resources.
At first this image may seem too vague—yet, even in this simple form, it suggests how minds could change their states. For example, in the case of Charles’s infatuation, this suggests that some process has switched off some resources that he normally uses to recognize someone else’s defects. The same process also arouses some other resources that tend to replace his more usual goals by ones that he think Celia wants him to hold.
Similarly, the state we call Anger appears to select a set of resources that help you react with more speed and strength—while also suppressing some other resources that usually make you act prudently; Anger replaces cautiousness with aggressiveness, trades empathy for hostility, and makes you plan less carefully.
More generally, this image suggests that there are some ‘Selectors’ built into our brains, which are wired to arouse and suppress certain particular sets of resources.
THESIS: Each of our major ‘emotional states’ results from turning some set of resources on and turning another set of them off. Each such selection will change how we think by changing our brain’s activities.
Why would a brain be equipped with such tricks? Each of them could have evolved to promote some special important function; anger and fear evolved for protection, and affection evolved to promote reproduction (which sometimes engages quite risky behaviors).
If several selectors are active at once, then some resources may be both aroused and suppressed. This could lead to the kinds of mental states in which we sometimes say, “our feelings are mixed.” Thus when some of your ‘Critics’ detect some sort of threat, this might activate Selectors that make you want both to attack and retreat, by arousing parts of both Anger and Fear.
Student: I could better grasp what you’re talking about, if you could be a bit more precise about what you mean by the word ‘resource.’ Do you imagine that each resource has a separate, definite place in the brain?
I’m using ‘resource’ in a hazy way, to refer to all sorts of structures and processes that range from perception and action to ways to think about bodies of knowledge. Some resources use functions that are performed in certain particular parts of the brain, while others use parts that are more widely spread over much larger portions of the brain. (We’ll discuss this more in §§Resources.
As we said, this resource-cloud idea may seem vague—but the rest of this book will develop more detailed ideas about what our mental resources could do—and how their activities lead to the ways that people come to think and behave. Then, as we proceed to develop those schemes, we’ll replace this vague Resource-Cloud idea scheme with more elaborate theories about how our resources are organized.
Romanticist: You speak of a person’s emotional states as nothing more than ways to think, but surely that’s too cold and abstract—too intellectual, dull, and mechanical. It says nothing about where feelings come in, with all their colors and intensities—or about our ambitions and goals. It doesn’t explain the pleasures and pains that come from when we succeed or fail, or how our bodies and minds interact, as when we’re aroused by works of art.
Rebecca West: “It overflows the confines of the mind and becomes an important physical event. The blood leaves the hands, the feet, the limbs, and flows back to the heart, which for the time seems to have become an immensely high temple whose pillars are several sorts of illumination, returning to the numb flesh diluted with some substance swifter and lighter and more electric than itself.”
In our usual, everyday views of ourselves, some of our feelings seem to be in our bodies—as when we’re affected by muscular tensions. However, our brains can’t directly detect those tensions themselves; instead, we sense signals that come up to our brains through nerves that run from those muscles and tendons. This means that we can see bodies, too, as composed of resources that brains can use.
So, instead of discussing emotions as though they were a distinctive kind of phenomenon, the rest of this book will show why it’s better to focus on what kinds of mental resources we have, what sorts of things those resources might do, how each affects the ones it’s connected to. And especially, we’ll develop ideas about what turns those resources off and on.
Student: Why should one ever turn off a resource? Why not keep them all working all the time?
Indeed, certain resources are never switched off—like those involved with vital functions like respiration, balance, and posture—nor are those that constantly keep watch for certain particular types of danger. However, if all our resources were active at once, then they would often get into conflicts. You can’t make your body both walk and run, or move in two different directions at once. How should we resolve such internal conflicts? In a human society, the simplest way is for individuals to compete. But when competition leads to excessive waste, then we find ways to organize ourselves into multiple levels of management, in which each manager has authority to decide among the options proposed by lower ones.
However, a human mind cannot be so hierarchical. This is because, in general, no single, lower-level resource will be able to solve any difficult problem by itself. So when a lower-level ‘Critic’ resource encounters a problem it needs to solve, then it may transiently need to take over control of one or more high-level strategies—for example, to divide the problem into simpler parts, or to remember how a similar problem was solved in the past, or to make a series of different attempts and then to compare and evaluate these. So a Critic may try to arouse several Selectors, each of which could lead to different way to think.
Now, each of such high-level strategies will need to use hundreds of lower-level processes, so if we tried to use several such ‘ways to think” at once, they would tend to interfere with each other—so we’ll still need some high level management. This could be one reason why our ‘thinking’ often seems to us more like a serial, step-by-step process than like one in which many things happen at once. However, every such high-level step will still need to engage many low-level processes that may need to work simultaneously. So the sense that our thoughts flow in serial streams must be in large part an illusion that comes because the higher-level parts of our minds know so little about those sub-processes. (We’ll discuss this more in §4 and §7.)
Critic: In any case, it seems to me that your Resource-Switching view is too radical. Perhaps it could be used to explain the behavior of an insect or fish—but Charles doesn’t switch, in the way you describe, to a totally different mental state. He changes some aspects of how he behaves, but surely he still remembers his name—and remains the same in most other ways.
It’s true that we’ve only presented a caricature. To develop our Cloud-of-Resources idea, we began with a simplified version in which each resource is either switched on or off. To some degree, this might apply to some of the actions of insects and fish—and to some of what human infants do, for they are prone to strong and quick changes in state. However, in the course of growing up, we develop techniques for “self-control” and our resources become much less clearly ‘switched.’ Instead, we arouse and suppress them to different extents, so that we still can listen and speak, and to access our bodies of knowledge and skills—though we’ll use these with different priorities. And through time we develop more intricate ways to control both old instincts and new processes, and to make new kinds of arrangements of them, in which multiple ones are active at once—and that’s when we speak of our feelings as mixed.
Behold the child, by nature's kindly
Pleas'd with a rattle, tickl'd with a straw:
Some livelier plaything gives his youth delight,
A little louder, but as empty quite:
Scarfs, garters, gold, amuse his riper stage,
And beads and pray'r books are the toys of age:”
– Alexander Pope in Essay on Man.
Often, when a young infant gets angry, that change seems as quick as the flip of a switch.
A certain infant could not bear frustration, and would react to each setback by throwing a tantrum. He’d hold his breath and his back would contract so that he’d fall rearward on his head.
A simple theory of how this might work would be that some separate ‘instincts’ compete until just one of them takes over control. However, that model cannot explain how, later, that child finds new ways to deal with frustration:
A few weeks later, that behavior had changed; no longer completely controlled by his rage, he could also add ways to protect himself, so that when he felt this coming on, he’d run to collapse on some soft, padded place.
This suggests that usually, in the infant brain, only one Selector can work at a time; this makes the system change states decisively, so that not many conflicts will arise. However, those infantile systems cannot solve the kinds of hard problems our children must face as they move into their later lives. This led our human brains to evolve higher-level systems in which some instincts that formerly were distinct now became increasingly mixed. But as those systems gained more abilities, they also gained new ways to make mistakes, so they also had to evolve new ways to control themselves—and this led to a great cascade of new kinds of mental developments.
We tend to regard a problem as ‘hard’ when we’ve tried several methods without making progress. But it isn’t enough just to know that you’re stuck: you’ll do better if you can recognize when you’re facing some particular type of barrier, impasse, or obstacle. For if you can diagnose what “Type of Problem” you face, this can help you to select a more appropriate “Way to Think.” So, later chapters of this book will suggest that to do such things, our brains replace some of their ancient “Rule-Based Reaction-Machines” by what we’ll call “Critic-Selector Machines.”
The simplest version of such a scheme would be almost the same as an “If-Then” machine of the kind described in §1-4. There, each “If” detects a certain real-world problem, which causes the system then to react with a certain pre-specified, real-world action. So the behaviors of simple If-Then machines are highly constrained and inflexible.
However, in a Critic-Selector type of machine, those Ifs and Thens are more general, because the resources called Critics can recognize, not just events in the external world, but problems or obstacles inside the mind. Then, those “Selectors” also are not confined to acting on things in the outer world, but can react to mental obstacles—by turning other resources on or off. This means a Critic-Selector machine need not just react to external events, but also can direct itself to switch to a different way to think. For example, it might first consider several reactions before it decides which one to use.
Of course, we’ll need more specific ideas about how each of those new Ways to think might work, and about how we come to develop them. We know that throughout our childhood years, our brains pass through multiple stages of growth, and Chapter §5 will conjecture that this results in at least these six levels of mental procedures.
Thus, an adult who encounters what might be a threat need not just react instinctively, but can proceed to deliberate on whether to retreat or attack—that is, to use higher-level strategies to choose among possible ways to react. This way, one can make thoughtful choice between the conditions of Anger and Fear—and if it seems more appropriate to intimidate an adversary, one can make oneself angry deliberately (although one may not be aware of doing this).
We know that these mental abilities grow over several years of one’s childhood. Then why is it that we can’t recollect much of that stretch of development? One reason for this could be that, during those years, we also develop new ways to build memories—and when we switch to using these, that makes it hard to retrieve and interpret the records we made in previous times. Perhaps those old memories still exist, but in forms that we no longer can comprehend—so we cannot remember how we progressed from infantile reaction-sets to using our new, adult ways to think. We’ve rebuilt our minds too many times to remember how our infancies felt!
Some habits are much more difficult to cure or change than others are. Hence a struggle may often be observed in animals between different instincts, or between an instinct and some habitual disposition; as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues again, or returns ashamed to his master; or as between the love of a female dog for her young puppies and for her master, —for she may be seen to slink away to them, as if half ashamed of not accompanying her master. —Charles Darwin, in The Descent of Man
This chapter has raised some questions about how people could change their states so much. When someone you know has fallen in love, it's almost as though a switch had been thrown, and a different program has started to run.
The Resource-Cloud image suggests that such a change could result when a certain “Selector” excites (or suppresses) a certain large set of resources. Thus Charles’s attraction to Celia becomes stronger when all his fault–finding Critics turn off.
Psychologist: Indeed, infatuations sometimes strike suddenly. But other emotions may flow and ebb slowly—and usually, in our later years, our mood-shifts tend to become less abrupt. Thus an adult may be slow to take offense, but may then go on to brood for months on even a small or imagined affront.
Our twenty-year-old tabby-cat shows few signs of human maturity. At one moment she'll be affectionate, and seek out our companionship. But after a time, in the blink of an eye, she'll rise to her feet and walk away, without any sign of saying goodbye—whereas our twelve-year-old canine pet will rarely depart without looking back—as though he’s expressing a certain regret. The cat’s moods seem to show one at a time, but the dog’s dispositions seem more mixed, and less as though controlled by a switch.
In either case, any large change in one’s set of active resources will cause a large change in one’s mental state. One way this could happen would be for a certain resource to directly arouse many others:
In this way, the Selectors we mentioned in §1-5 could directly have substantial effects. Furthermore, if the set of newly aroused resources includes one or more other Selector resources, then this will cause a yet larger change, by activating yet more resources. Then these in turn may begin to arouse yet other resources that they need—and if each such change leads to yet several more, this spreading could escalate what we’ll call a large-scale “cascade.”
The further these activities spread, the more they will alter your Way to Think—and if your behavior then changes enough, then your friends might get the impression that you have turned into a different person.
Critic: That would be an exaggeration, because Charles will still be the very same person. He will still speak the same language and use the same knowledge; he’ll just have some different attitudes.
Of course, those cascades won’t change everything. When Charles adopts a new Way to Think, in many respects he’ll still be the same—because not all his resources will have been replaced. He still will be able to see and hear—but now he’ll perceive things in different ways. And because he now represents them in different ways, he’ll get different ideas about what those things or events might “mean.”
Charles will also still know how to talk—but may now use different styles of speech, and choose different subjects to talk about because, although he still has access to the same knowledge, skills, and memories, now different ones will be retrieved. He still may maintain the same plans and goals—but now they’ll have different priorities. He may still get dressed and go to work—but in some of those states he won’t dress so well. And so far as Charles, himself is concerned, he still has the same identity.
To what extent, then, will Charles be aware of such changes in his mental condition? He sometimes won’t notice those changes at all—but at other times, he may find himself making remarks to himself like, " I am getting angry now." To do this, his brain must have ways to “reflect” on some of its recent activities (for example, by recognizing the spread of some large-scale cascades). Chapter §4 will discuss how such processes could lead to some aspects of what we call “consciousness.”
What are dispositions and moods?
We all use many different words to vaguely describe how we feel and behave. We know that angry people more quickly react (but, usually, less cautiously) and that happy people less often start fights—but terms like these do not suggest ideas about how those states affect how we think. We recognize this when we deal with machines: Imagine that your car won't start—but when you ask your mechanic for help, you only receive a reply like this:
"It appears that your car doesn’t want to run. Perhaps it's become annoyed with you because you haven’t been treating it well."
But psychological terms like these don’t help you to get good ideas to explain the behavior of your car. Perhaps you towed too heavy a load and broke some of the teeth of one of the gears. Or perhaps you left the lights on all night, and completely discharged the battery. Then those ‘mentalistic’ descriptions won’t help you; to diagnose and repair what’s wrong; you need to know about that car’s parts.
That’s where the view of a mind as a Cloud of Resources is better than the Single-Self view; it encourages us to look at the parts instead of the whole. Is there something wrong with the starter switch? Has the fuel tank been completely drained? Those commonsense psychology-words are useful in everyday social life, but to better understand our minds we need more ideas about their insides.
To what extents are emotions innate? It would seem that all normal person share some common emotions, such as anger, fear, sadness, joy, disgust, and surprise—and some would also include curiosity. However, psychologists do not broadly agree about which of these are innate and which are learned; for example, some of them regard anger as based on fear. This book will not get involved in that debate, because it is more concerned with what emotions are—in the sense of being ‘ways to think’—than with finding ways to classify them. 
How do Chemicals affect our Minds?
Physiologist: Your ideas about switching resources sound good, but can all mental states be explained in that way? Aren’t we also affected by chemicals like hormones, endorphins, and neurotransmitters?
There’s no doubt that such chemicals do affect the internal states of our brains—but the view that those effects are direct is a popular but bad mistake—somewhat like the error that someone would make by supposing that rain makes umbrellas unfold. Here’s how one author depicts what this misses:
Susanna Kaysen: “Too much acetylcholine, not enough serotonin, and you've got a depression. So, what's left of mind? It's a long way from not having enough serotonin to thinking the world is "stale, flat and unprofitable"; even further to writing a play about a man driven by that thought.” 
For just as the meaning of each separate word depends on the sentence that it is in, the effect of each chemical on the brain depends on all the particular ways in which each of your brain-cells react to it—each type of cell may differ in that. So the effect of each chemical will depend which brain-cells react to it—and then on how other cells in that happen to be connected to these, etc. So the large-scale effect of each chemical depends, not only on where and when it’s released, but also on the other details of the interconnections inside your brain. We’ll discuss more details in §§Chemicals.
How could machines understand what things mean?
In the popular view, machines do things without understanding what their activities mean. But what does ‘understanding’ mean? Even our best philosophers have failed to explain what we mean by words like “understand.”
However, we should not complain about that, because this is precisely the way it should be! For, most of our common psychology-words have this peculiar property: the more clearly you try to define them, the less you capture their commonsense meanings. And this applies especially to words like understand and mean!
If you 'understand' something in only one way then you scarcely understand it at all. For then, if anything should go wrong, you'll have no other place to go. But if you represent something in multiple ways, then when one of them fails you can switch to another—until you find one that works for you.
It’s the same when you face a new kind of problem:
If you only know a single technique, then you’ll get stuck when that method fails. But if you have multiple ways to proceed, then whenever you get into trouble, you’ll be able to switch to a different technique.
We switch how we think so fluently that we scarcely aware that we’re doing this—except when this leads to cascades so great that we notice a change in emotional state. One of the central goals of this book is to describe the variety of our mental resources, and how these might be organized—and the final chapters of this book will show that much of our human resourcefulness depends upon on having multiple ways to escape from getting stuck.
Why do we think that we have Selves?
Citizen: If my mental resources keep changing so much, then what gives me the sense that I’m still the same Self—no matter how happy or angry I get?
We do not have any good evidence that young infants start out with any such sense—and we can’t trust our infantile memories. Then why do all of us come to believe that somewhere, deep in the heart of each mind, there exists some permanent entity that experiences all our feelings and thoughts? Here’s what I think might lead to this:
In early life, our low-level processes solve many small problems without any sense of what’s doing it. And when those processes run into trouble, then those processes simply stop, and the mind simply starts doing something else.
However, as we develop more levels of thought, those higher levels try to find out “what went wrong” and to improve our skills for this, we start to construct new ways to portray aspects of our recent thoughts. Eventually these develop into simplified ‘models’ of ourselves.
Perhaps the simplest and most common such model is composed of parts like these:
However, every normal person also builds many other kinds of self-models that try to describe how they think about such subjects as their social relationships, physical skills, political views, and economic, spiritual, and sexual attitudes. Chapter §9 will go on to suggest that what each person calls his or her ‘Self’ is a great network of such ‘mental models’—each of which attempts to describe only certain aspects of a person’s own mind.
Why have multiple models of Selves?
Physicist: Why not simply combine all those models into a single, unified one that merges the virtues of all those separate ones?
That probably would not be practical, because such a structure would be too large for us to ‘keep in mind’ all its details at once. This suggests that the limitations of our brains must constrain us, at each particular moment, to superimpose a few model-cartoons—each by itself too incomplete to answer most questions about yourself.
Besides, for each particular such kind of problem, some of those models will help more than others—by highlighting the most relevant features. This means both that you need to use multiple views, and that you need ways to rapidly switch among them. Let’s listen to Richard Feynman again:
"...Psychologically we must keep all the theories in our heads, and every theoretical physicist who is any good knows six or seven different theoretical representations for exactly the same physics. He knows that they are all equivalent, and that nobody is ever going to be able to decide which one is right at that level, but he keeps them in his head, hoping that they will give him different ideas for guessing."
The key word here is ‘guess’ because every such theory has virtues and faults; no single model or representation is best for every different purpose or goal—and each is likely to get you stuck in certain kinds of predicaments.
How do we develop new goals and ideas?
The next few chapters will take the commonsense view that everyone already knows what goals are, and focus instead on questions about how we come to acquire them. However, that discussion will be incomplete until we present (in Chapter §6) more detailed ideas about how goals work.
In the usual view of how human minds grow, each child begins with instinctive reactions, but then goes through stages of mental growth that overlay these with additional layers and levels of goals. Those older instincts may still remain, but these new resources gain increasing control—until we can think about our own motives and goals, and perhaps try to change or reformulate them.
But what possible basis could we use for learning to appraise ourselves? How could we choose which new goals to adopt—and how could we possibly justify them? No infant could ever be wise enough to make good such choices by itself. So the following chapter will argue that our brains must have evolved, instead, ways to copy the ideals and attitudes of our parents, friends, and acquaintances!
 See www.english.uiuc.edu/maps/poets/m_r/parker/lightverse.htm
Barry Took and Marty Feldman, Round the Horne, BBC Radio, 1966
 This list is adapted from a note from Aaron Sloman in comp.ai.philosophy, 16/5/1995.
 Nikolaas Tinbergen, The Study of Instinct, Oxford University Press, London, 1951. [See §§Tinbergen’s Theory.]
 In The Strange Necessity, 1928. ISBN: 0781270626.
 See Glossary: Cross-Exclusion.
 However, I recommend Aaron Sloman’s discussion of this in http://www.cs.bham.ac.uk/~axs/misc/talks/gatsby.slides.pdf.
 In Girl, Interrupted, Vintage Books, 1994, pp. 137-143.
 Such an ‘all-or-none’ view of what 'understand'' means can be seen at http://home.hanmir.com/~prolog/ai/mind.html or in“Minds, Brains, and Computers” by John Searle, in Philosophy: The Quest for Truth. Oxford Univ. Press; 5th edition, ISBN: 0195156242
 R. Feynman, The Character of Physical Law, Modern Library, 1994, ISBN: 0679601279. Note that when scientists say that two are representations are ‘equivalent,’ they do not mean to suggest that both are equally practical.