Group items tagged

Some of the most common types of illusory percepts are those that affect the impression of size, length or distance.

As visual processing needs to be both rapid and generally accurate, the brain constantly uses shortcuts and makes assumptions about the world that can, in some cases, be misleading.

These illusions are the result of visual processes shaped by evolution. Using that process may have been once beneficial (or still is), but it also allows our brains to be tricked.

if animals are tricked by the same illusions, then perhaps revealing why a different evolutionary path leads to the same visual process might help us understand why evolution favours this development.

Great bowerbirds could be the ultimate illusory artists. For example, their males construct forced perspective illusions to make them more attractive to mates.

When a male has two smaller clawed males on either side of him he is more attractive to a female (because he looks relatively larger) than if he was surrounded by two larger clawed males.

This effect is known as the Ebbinghaus illusion (see image), and suggests that males may easily manipulate their perceived attractiveness by surrounding themselves with less attractive rivals.

Deceptions of the senses are the truths of perception.

Visual illusions (and those in the non-visual senses) are a crucial tool for determining what perceptual assumptions animals make about the world around them.

no differences between the groups were identified in correctly naming the colours of the squares

brain activation of all participants was measured while they looked at the photo of The Dress via a computer-based presentation system

participants looked at coloured squares with the same colour properties as the photo of The Dress

tested participants who perceived the dress as white-gold or black-blue

They demonstrated that in a direct comparison of groups the photo triggered differential brain activation, depending on their perception

participants who saw the dress as white-gold presented additional activation, mainly in frontal and parietal brain areas

Frontal regions are particularly involved in higher cognitive processes such as selective attention and decision making

Before, no optical illusion existed with exactly two competing perceptions which could not be deliberately manipulated

research group succeeded in identifying brain areas which cause optical illusions

thus we have laid a foundation for further research in the field of visual processing

A horizontal pattern of raised lines going across the pavement tells blind pedestrians they are on the footpath side; raised lines running along the direction of travel indicate the side designated for cycles. A wide, raised line divides the two.

Because the raised bumps are unpleasant to ride across, cyclists instinctively are drawn toward the tramline pattern which runs in the same direction as they are traveling.

Elsewhere, it is possible to find raised, rounded ribs running across pavement, creating a corduroy pattern. They look like they might be there to provide additional grip; in fact, they are sending a warning to anyone who stands on them about what is ahead.

The idea is to guide people through busy areas and around objects by drawing them along these raised lines.

They found that uncertainty about the layout of the road ahead is a powerful way of getting drivers to slow down.

triangles painted along the edge of each road – create an impression of a narrower road for example, and make drivers more cautious.

They have been painting boxes onto the road that use a clever combination of white and dark paint to create the illusion of a speed hump.

In India, they have taken things even further by painting deliberate optical illusions to give the impression that obstacles are in the road ahead.

Confirmation bias shows up most blatantly in our current political divide, where each side seems unable to allow that the other side is right about anything.

The whole idea of cognitive biases and faulty heuristics—the shortcuts and rules of thumb by which we make judgments and predictions—was more or less invented in the 1970s by Amos Tversky and Daniel Kahneman

versky died in 1996. Kahneman won the 2002 Nobel Prize in Economics for the work the two men did together, which he summarized in his 2011 best seller, Thinking, Fast and Slow. Another best seller, last year’s The Undoing Project, by Michael Lewis, tells the story of the sometimes contentious collaboration between Tversky and Kahneman

Another key figure in the field is the University of Chicago economist Richard Thaler. One of the biases he’s most linked with is the endowment effect, which leads us to place an irrationally high value on our possessions.

In an experiment conducted by Thaler, Kahneman, and Jack L. Knetsch, half the participants were given a mug and then asked how much they would sell it for. The average answer was $5.78. The rest of the group said they would spend, on average, $2.21 for the same mug. This flew in the face of classic economic theory, which says that at a given time and among a certain population, an item has a market value that does not depend on whether one owns it or not. Thaler won the 2017 Nobel Prize in Economics.

“The question that is most often asked about cognitive illusions is whether they can be overcome. The message … is not encouraging.”

that’s not so easy in the real world, when we’re dealing with people and situations rather than lines. “Unfortunately, this sensible procedure is least likely to be applied when it is needed most,” Kahneman writes. “We would all like to have a warning bell that rings loudly whenever we are about to make a serious error, but no such bell is available.”

At least with the optical illusion, our slow-thinking, analytic mind—what Kahneman calls System 2—will recognize a Müller-Lyer situation and convince itself not to trust the fast-twitch System 1’s perception

Kahneman and others draw an analogy based on an understanding of the Müller-Lyer illusion, two parallel lines with arrows at each end. One line’s arrows point in; the other line’s arrows point out. Because of the direction of the arrows, the latter line appears shorter than the former, but in fact the two lines are the same length.

Because biases appear to be so hardwired and inalterable, most of the attention paid to countering them hasn’t dealt with the problematic thoughts, judgments, or predictions themselves

Is it really impossible, however, to shed or significantly mitigate one’s biases? Some studies have tentatively answered that question in the affirmative.

what if the person undergoing the de-biasing strategies was highly motivated and self-selected? In other words, what if it was me?

Over an apple pastry and tea with milk, he told me, “Temperament has a lot to do with my position. You won’t find anyone more pessimistic than I am.”

I met with Kahneman

“I see the picture as unequal lines,” he said. “The goal is not to trust what I think I see. To understand that I shouldn’t believe my lying eyes.” That’s doable with the optical illusion, he said, but extremely difficult with real-world cognitive biases.

In this context, his pessimism relates, first, to the impossibility of effecting any changes to System 1—the quick-thinking part of our brain and the one that makes mistaken judgments tantamount to the Müller-Lyer line illusion

he most effective check against them, as Kahneman says, is from the outside: Others can perceive our errors more readily than we can.

“slow-thinking organizations,” as he puts it, can institute policies that include the monitoring of individual decisions and predictions. They can also require procedures such as checklists and “premortems,”

A premortem attempts to counter optimism bias by requiring team members to imagine that a project has gone very, very badly and write a sentence or two describing how that happened. Conducting this exercise, it turns out, helps people think ahead.

“My position is that none of these things have any effect on System 1,” Kahneman said. “You can’t improve intuition.

Perhaps, with very long-term training, lots of talk, and exposure to behavioral economics, what you can do is cue reasoning, so you can engage System 2 to follow rules. Unfortunately, the world doesn’t provide cues. And for most people, in the heat of argument the rules go out the window.

Kahneman describes an even earlier Nisbett article that showed subjects’ disinclination to believe statistical and other general evidence, basing their judgments instead on individual examples and vivid anecdotes. (This bias is known as base-rate neglect.)

over the years, Nisbett had come to emphasize in his research and thinking the possibility of training people to overcome or avoid a number of pitfalls, including base-rate neglect, fundamental attribution error, and the sunk-cost fallacy.

Nisbett’s second-favorite example is that economists, who have absorbed the lessons of the sunk-cost fallacy, routinely walk out of bad movies and leave bad restaurant meals uneaten.

When Nisbett asks the same question of students who have completed the statistics course, about 70 percent give the right answer. He believes this result shows, pace Kahneman, that the law of large numbers can be absorbed into System 2—and maybe into System 1 as well, even when there are minimal cues.

about half give the right answer: the law of large numbers, which holds that outlier results are much more frequent when the sample size (at bats, in this case) is small. Over the course of the season, as the number of at bats increases, regression to the mean is inevitabl

When Nisbett has to give an example of his approach, he usually brings up the baseball-phenom survey. This involved telephoning University of Michigan students on the pretense of conducting a poll about sports, and asking them why there are always several Major League batters with .450 batting averages early in a season, yet no player has ever finished a season with an average that high.

we’ve tested Michigan students over four years, and they show a huge increase in ability to solve problems. Graduate students in psychology also show a huge gain.”

, “I know from my own research on teaching people how to reason statistically that just a few examples in two or three domains are sufficient to improve people’s reasoning for an indefinitely large number of events.”

isbett suggested another factor: “You and Amos specialized in hard problems for which you were drawn to the wrong answer. I began to study easy problems, which you guys would never get wrong but untutored people routinely do … Then you can look at the effects of instruction on such easy problems, which turn out to be huge.”

Nisbett suggested that I take “Mindware: Critical Thinking for the Information Age,” an online Coursera course in which he goes over what he considers the most effective de-biasing skills and concepts. Then, to see how much I had learned, I would take a survey he gives to Michigan undergraduates. So I did.

he course consists of eight lessons by Nisbett—who comes across on-screen as the authoritative but approachable psych professor we all would like to have had—interspersed with some graphics and quizzes. I recommend it. He explains the availability heuristic this way: “People are surprised that suicides outnumber homicides, and drownings outnumber deaths by fire. People always think crime is increasing” even if it’s not.

When I finished the course, Nisbett sent me the survey he and colleagues administer to Michigan undergrads

It contains a few dozen problems meant to measure the subjects’ resistance to cognitive biases

I got it right. Indeed, when I emailed my completed test, Nisbett replied, “My guess is that very few if any UM seniors did as well as you. I’m sure at least some psych students, at least after 2 years in school, did as well. But note that you came fairly close to a perfect score.”

Nevertheless, I did not feel that reading Mindware and taking the Coursera course had necessarily rid me of my biases

For his part, Nisbett insisted that the results were meaningful. “If you’re doing better in a testing context,” he told me, “you’ll jolly well be doing better in the real world.”

The New York–based NeuroLeadership Institute offers organizations and individuals a variety of training sessions, webinars, and conferences that promise, among other things, to use brain science to teach participants to counter bias. This year’s two-day summit will be held in New York next month; for $2,845, you could learn, for example, “why are our brains so bad at thinking about the future, and how do we do it better?”

Philip E. Tetlock, a professor at the University of Pennsylvania’s Wharton School, and his wife and research partner, Barbara Mellers, have for years been studying what they call “superforecasters”: people who manage to sidestep cognitive biases and predict future events with far more accuracy than the pundits

One of the most important ingredients is what Tetlock calls “the outside view.” The inside view is a product of fundamental attribution error, base-rate neglect, and other biases that are constantly cajoling us into resting our judgments and predictions on good or vivid stories instead of on data and statistics

In 2006, seeking to prevent another mistake of that magnitude, the U.S. government created the Intelligence Advanced Research Projects Activity (iarpa), an agency designed to use cutting-edge research and technology to improve intelligence-gathering and analysis. In 2011, iarpa initiated a program, Sirius, to fund the development of “serious” video games that could combat or mitigate what were deemed to be the six most damaging biases: confirmation bias, fundamental attribution error, the bias blind spot (the feeling that one is less biased than the average person), the anchoring effect, the representativeness heuristic, and projection bias (the assumption that everybody else’s thinking is the same as one’s own).

most promising are a handful of video games. Their genesis was in the Iraq War

Together with collaborators who included staff from Creative Technologies, a company specializing in games and other simulations, and Leidos, a defense, intelligence, and health research company that does a lot of government work, Morewedge devised Missing. Some subjects played the game, which takes about three hours to complete, while others watched a video about cognitive bias. All were tested on bias-mitigation skills before the training, immediately afterward, and then finally after eight to 12 weeks had passed.

“The literature on training suggests books and classes are fine entertainment but largely ineffectual. But the game has very large effects. It surprised everyone.”

he said he saw the results as supporting the research and insights of Richard Nisbett. “Nisbett’s work was largely written off by the field, the assumption being that training can’t reduce bias,

even the positive results reminded me of something Daniel Kahneman had told me. “Pencil-and-paper doesn’t convince me,” he said. “A test can be given even a couple of years later. But the test cues the test-taker. It reminds him what it’s all about.”

Morewedge told me that some tentative real-world scenarios along the lines of Missing have shown “promising results,” but that it’s too soon to talk about them.

In the future, I will monitor my thoughts and reactions as best I can

the illusion was mistakenly referred to as a scientific personality test of right brain/left brain dominance by numerous websites and blogs. In reality, the spinning dancer illusion is related to a bistable perception in which an ambiguous 2-dimensional figure can be seen from two different perspectives.

According to this principle, objects that are grouped together tend to be seen as being part of a whole. We tend to ignore gaps and perceive the contour lines in order to make the image appear as a cohesive whole.

Sartre listened to his problem and said simply, ‘You are free, therefore choose — that is to say, invent.’ No signs are vouchsafed in this world, he said. None of the old authorities can relieve you of the burden of freedom. You can weigh up moral or practical considerations as carefully as you like, but ultimately you must take the plunge and do something, and it’s up to you what that something is.

Even if the situation is unbearable — perhaps you are facing execution, or sitting in a Gestapo prison, or about to fall off a cliff — you are still free to decide what to make of it in mind and deed. Starting from where you are now, you choose. And in choosing, you also choose who you will be.

The war had made people realise that they and their fellow humans were capable of departing entirely from civilised norms; no wonder the idea of a fixed human nature seemed questionable.

If this sounds difficult and unnerving, it’s because it is. Sartre does not deny that the need to keep making decisions brings constant anxiety. He heightens this anxiety by pointing out that what you do really matters. You should make your choices as though you were choosing on behalf of the whole of humanity, taking the entire burden of responsibility for how the human race behaves. If you avoid this responsibility by fooling yourself that you are the victim of circumstance or of someone else’s bad advice, you are failing to meet the demands of human life and choosing a fake existence, cut off from your own ‘authenticity’.

Along with the terrifying side of this comes a great promise: Sartre’s existentialism implies that it is possible to be authentic and free, as long as you keep up the effort.

almost all agreed that it was, as an article in Les nouvelles littéraires phrased it, a ‘sickening mixture of philosophic pretentiousness, equivocal dreams, physiological technicalities, morbid tastes and hesitant eroticism … an introspective embryo that one would take distinct pleasure in crushing’.

he offered a philosophy designed for a species that had just scared the hell out of itself, but that finally felt ready to grow up and take responsibility.

In this rebellious world, just as with the Parisian bohemians and Dadaists in earlier generations, everything that was dangerous and provocative was good, and everything that was nice or bourgeois was bad.

Such interweaving of ideas and life had a long pedigree, although the existentialists gave it a new twist. Stoic and Epicurean thinkers in the classical world had practised philosophy as a means of living well, rather than of seeking knowledge or wisdom for their own sake. By reflecting on life’s vagaries in philosophical ways, they believed they could become more resilient, more able to rise above circumstances, and better equipped to manage grief, fear, anger, disappointment or anxiety.

In the tradition they passed on, philosophy is neither a pure intellectual pursuit nor a collection of cheap self-help tricks, but a discipline for flourishing and living a fully human, responsible life.

For Kierkegaard, Descartes had things back to front. In his own view, human existence comes first: it is the starting point for everything we do, not the result of a logical deduction. My existence is active: I live it and choose it, and this precedes any statement I can make about myself.

Studying our own moral genealogy cannot help us to escape or transcend ourselves. But it can enable us to see our illusions more clearly and lead a more vital, assertive existence.

What was needed, he felt, was not high moral or theological ideals, but a deeply critical form of cultural history or ‘genealogy’ that would uncover the reasons why we humans are as we are, and how we came to be that way. For him, all philosophy could even be redefined as a form of psychology, or history.

For those oppressed on grounds of race or class, or for those fighting against colonialism, existentialism offered a change of perspective — literally, as Sartre proposed that all situations be judged according to how they appeared in the eyes of those most oppressed, or those whose suffering was greatest.

She observed that we need not expect moral philosophers to ‘live by’ their ideas in a simplistic way, as if they were following a set of rules. But we can expect them to show how their ideas are lived in. We should be able to look in through the windows of a philosophy, as it were, and see how people occupy it, how they move about and how they conduct themselves.

the existentialists inhabited their historical and personal world, as they inhabited their ideas. This notion of ‘inhabited philosophy’ is one I’ve borrowed from the English philosopher and novelist Iris Murdoch, who wrote the first full-length book on Sartre and was an early adopter of existentialism

What is existentialism anyway?

An existentialist who is also phenomenological provides no easy rules for dealing with this condition, but instead concentrates on describing lived experience as it presents itself. — By describing experience well, he or she hopes to understand this existence and awaken us to ways of living more authentic lives.

Existentialists concern themselves with individual, concrete human existence. — They consider human existence different from the kind of being other things have. Other entities are what they are, but as a human I am whatever I choose to make of myself at every moment. I am free — — and therefore I’m responsible for everything I do, a dizzying fact which causes — an anxiety inseparable from human existence itself.

On the other hand, I am only free within situations, which can include factors in my own biology and psychology as well as physical, historical and social variables of the world into which I have been thrown. — Despite the limitations, I always want more: I am passionately involved in personal projects of all kinds. — Human existence is thus ambiguous: at once boxed in by borders and yet transcendent and exhilarating. —

The first part of this is straightforward: a phenomenologist’s job is to describe. This is the activity that Husserl kept reminding his students to do. It meant stripping away distractions, habits, clichés of thought, presumptions and received ideas, in order to return our attention to what he called the ‘things themselves’. We must fix our beady gaze on them and capture them exactly as they appear, rather than as we think they are supposed to be.

Husserl therefore says that, to phenomenologically describe a cup of coffee, I should set aside both the abstract suppositions and any intrusive emotional associations. Then I can concentrate on the dark, fragrant, rich phenomenon in front of me now. This ‘setting aside’ or ‘bracketing out’ of speculative add-ons Husserl called epoché — a term borrowed from the ancient Sceptics,

The point about rigour is crucial; it brings us back to the first half of the command to describe phenomena. A phenomenologist cannot get away with listening to a piece of music and saying, ‘How lovely!’ He or she must ask: is it plaintive? is it dignified? is it colossal and sublime? The point is to keep coming back to the ‘things themselves’ — phenomena stripped of their conceptual baggage — so as to bail out weak or extraneous material and get to the heart of the experience.

Husserlian ‘bracketing out’ or epoché allows the phenomenologist to temporarily ignore the question ‘But is it real?’, in order to ask how a person experiences his or her world. Phenomenology gives a formal mode of access to human experience. It lets philosophers talk about life more or less as non-philosophers do, while still being able to tell themselves they are being methodical and rigorous.

Besides claiming to transform the way we think about reality, phenomenologists promised to change how we think about ourselves. They believed that we should not try to find out what the human mind is, as if it were some kind of substance. Instead, we should consider what it does, and how it grasps its experiences.

For Brentano, this reaching towards objects is what our minds do all the time. Our thoughts are invariably of or about something, he wrote: in love, something is loved, in hatred, something is hated, in judgement, something is affirmed or denied. Even when I imagine an object that isn’t there, my mental structure is still one of ‘about-ness’ or ‘of-ness’.

Except in deepest sleep, my mind is always engaged in this aboutness: it has ‘intentionality’. Having taken the germ of this from Brentano, Husserl made it central to his whole philosophy.

Husserl saw in the idea of intentionality a way to sidestep two great unsolved puzzles of philosophical history: the question of what objects ‘really’ are, and the question of what the mind ‘really’ is. By doing the epoché and bracketing out all consideration of reality from both topics, one is freed to concentrate on the relationship in the middle. One can apply one’s descriptive energies to the endless dance of intentionality that takes place in our lives: the whirl of our minds as they seize their intended phenomena one after the other and whisk them around the floor,

Understood in this way, the mind hardly is anything at all: it is its aboutness. This makes the human mind (and possibly some animal minds) different from any other naturally occurring entity. Nothing else can be as thoroughly about or of things as the mind is:

Some Eastern meditation techniques aim to still this scurrying creature, but the extreme difficulty of this shows how unnatural it is to be mentally inert. Left to itself, the mind reaches out in all directions as long as it is awake — and even carries on doing it in the dreaming phase of its sleep.

a mind that is experiencing nothing, imagining nothing, or speculating about nothing can hardly be said to be a mind at all.

Three simple ideas — description, phenomenon, intentionality — provided enough inspiration to keep roomfuls of Husserlian assistants busy in Freiburg for decades. With all of human existence awaiting their attention, how could they ever run out of things to do?

For Sartre, this gives the mind an immense freedom. If we are nothing but what we think about, then no predefined ‘inner nature’ can hold us back. We are protean.

way of this interpretation. Real, not real; inside, outside; what difference did it make? Reflecting on this, Husserl began turning his phenomenology into a branch of ‘idealism’ — the philosophical tradition which denied external reality and defined everything as a kind of private hallucination.

For Sartre, if we try to shut ourselves up inside our own minds, ‘in a nice warm room with the shutters closed’, we cease to exist. We have no cosy home: being out on the dusty road is the very definition of what we are.

One might think that, if Heidegger had anything worth saying, he could have communicated it in ordinary language. The fact is that he does not want to be ordinary, and he may not even want to communicate in the usual sense. He wants to make the familiar obscure, and to vex us. George Steiner thought that Heidegger’s purpose was less to be understood than to be experienced through a ‘felt strangeness’.

He takes Dasein in its most ordinary moments, then talks about it in the most innovative way he can. For Heidegger, Dasein’s everyday Being is right here: it is Being-in-the-world, or In-der-Welt-sein. The main feature of Dasein’s everyday Being-in-the-world right here is that it is usually busy doing something.

Thus, for Heidegger, all Being-in-the-world is also a ‘Being-with’ or Mitsein. We cohabit with others in a ‘with-world’, or Mitwelt. The old philosophical problem of how we prove the existence of other minds has now vanished. Dasein swims in the with-world long before it wonders about other minds.

Sometimes the best-educated people were those least inclined to take the Nazis seriously, dismissing them as too absurd to last. Karl Jaspers was one of those who made this mistake, as he later recalled, and Beauvoir observed similar dismissive attitudes among the French students in Berlin.

In any case, most of those who disagreed with Hitler’s ideology soon learned to keep their view to themselves. If a Nazi parade passed on the street, they would either slip out of view or give the obligatory salute like everyone else, telling themselves that the gesture meant nothing if they did not believe in it. As the psychologist Bruno Bettelheim later wrote of this period, few people will risk their life for such a small thing as raising an arm — yet that is how one’s powers of resistance are eroded away, and eventually one’s responsibility and integrity go with them.

for Arendt, if you do not respond adequately when the times demand it, you show a lack of imagination and attention that is as dangerous as deliberately committing an abuse. It amounts to disobeying the one command she had absorbed from Heidegger in those Marburg days: Think!

‘Everything takes place under a kind of anaesthesia. Objectively dreadful events produce a thin, puny emotional response. Murders are committed like schoolboy pranks. Humiliation and moral decay are accepted like minor incidents.’ Haffner thought modernity itself was partly to blame: people had become yoked to their habits and to mass media, forgetting to stop and think, or to disrupt their routines long enough to question what was going on.

Heidegger’s former lover and student Hannah Arendt would argue, in her 1951 study The Origins of Totalitarianism, that totalitarian movements thrived at least partly because of this fragmentation in modern lives, which made people more vulnerable to being swept away by demagogues. Elsewhere, she coined the phrase ‘the banality of evil’ to describe the most extreme failures of personal moral awareness.

His communicative ideal fed into a whole theory of history: he traced all civilisation to an ‘Axial Period’ in the fifth century BC, during which philosophy and culture exploded simultaneously in Europe, the Middle East and Asia, as though a great bubble of minds had erupted from the earth’s surface. ‘True philosophy needs communion to come into existence,’ he wrote, and added, ‘Uncommunicativeness in a philosopher is virtually a criterion of the untruth of his thinking.’

The idea of being called to authenticity became a major theme in later existentialism, the call being interpreted as saying something like ‘Be yourself!’, as opposed to being phony. For Heidegger, the call is more fundamental than that. It is a call to take up a self that you didn’t know you had: to wake up to your Being. Moreover, it is a call to action. It requires you to do something: to take a decision of some sort.

Being and Time contained at least one big idea that should have been of use in resisting totalitarianism. Dasein, Heidegger wrote there, tends to fall under the sway of something called das Man or ‘the they’ — an impersonal entity that robs us of the freedom to think for ourselves. To live authentically requires resisting or outwitting this influence, but this is not easy because das Man is so nebulous. Man in German does not mean ‘man’ as in English (that’s der Mann), but a neutral abstraction, something like ‘one’ in the English phrase ‘one doesn’t do that’,

for Heidegger, das Man is me. It is everywhere and nowhere; it is nothing definite, but each of us is it. As with Being, it is so ubiquitous that it is difficult to see. If I am not careful, however, das Man takes over the important decisions that should be my own. It drains away my responsibility or ‘answerability’. As Arendt might put it, we slip into banality, failing to think.

Jaspers focused on what he called Grenzsituationen — border situations, or limit situations. These are the moments when one finds oneself constrained or boxed in by what is happening, but at the same time pushed by these events towards the limits or outer edge of normal experience. For example, you might have to make a life-or-death choice, or something might remind you suddenly of your mortality,

Jaspers’ interest in border situations probably had much to do with his own early confrontation with mortality. From childhood, he had suffered from a heart condition so severe that he always expected to die at any moment. He also had emphysema, which forced him to speak slowly, taking long pauses to catch his breath. Both illnesses meant that he had to budget his energies with care in order to get his work done without endangering his life.

If I am to resist das Man, I must become answerable to the call of my ‘voice of conscience’. This call does not come from God, as a traditional Christian definition of the voice of conscience might suppose. It comes from a truly existentialist source: my own authentic self. Alas, this voice is one I do not recognise and may not hear, because it is not the voice of my habitual ‘they-self’. It is an alien or uncanny version of my usual voice. I am familiar with my they-self, but not with my unalienated voice — so, in a weird twist, my real voice is the one that sounds strangest to me.

Marcel developed a strongly theological branch of existentialism. His faith distanced him from both Sartre and Heidegger, but he shared a sense of how history makes demands on individuals. In his essay ‘On the Ontological Mystery’, written in 1932 and published in the fateful year of 1933, Marcel wrote of the human tendency to become stuck in habits, received ideas, and a narrow-minded attachment to possessions and familiar scenes. Instead, he urged his readers to develop a capacity for remaining ‘available’ to situations as they arise. Similar ideas of disponibilité or availability had been explored by other writers,

Marcel made it his central existential imperative. He was aware of how rare and difficult it was. Most people fall into what he calls ‘crispation’: a tensed, encrusted shape in life — ‘as though each one of us secreted a kind of shell which gradually hardened and imprisoned him’.

Bettelheim later observed that, under Nazism, only a few people realised at once that life could not continue unaltered: these were the ones who got away quickly. Bettelheim himself was not among them. Caught in Austria when Hitler annexed it, he was sent first to Dachau and then to Buchenwald, but was then released in a mass amnesty to celebrate Hitler’s birthday in 1939 — an extraordinary reprieve, after which he left at once for America.

we are used to reading philosophy as offering a universal message for all times and places — or at least as aiming to do so. But Heidegger disliked the notion of universal truths or universal humanity, which he considered a fantasy. For him, Dasein is not defined by shared faculties of reason and understanding, as the Enlightenment philosophers thought. Still less is it defined by any kind of transcendent eternal soul, as in religious tradition. We do not exist on a higher, eternal plane at all. Dasein’s Being is local: it has a historical situation, and is constituted in time and place.

For Marcel, learning to stay open to reality in this way is the philosopher’s prime job. Everyone can do it, but the philosopher is the one who is called on above all to stay awake, so as to be the first to sound the alarm if something seems wrong.

Second, it also means understanding that we are historical beings, and grasping the demands our particular historical situation is making on us. In what Heidegger calls ‘anticipatory resoluteness’, Dasein discovers ‘that its uttermost possibility lies in giving itself up’. At that moment, through Being-towards-death and resoluteness in facing up to one’s time, one is freed from the they-self and attains one’s true, authentic self.

If we are temporal beings by our very nature, then authentic existence means accepting, first, that we are finite and mortal. We will die: this all-important realisation is what Heidegger calls authentic ‘Being-towards-Death’, and it is fundamental to his philosophy.

Hannah Arendt, instead, left early on: she had the benefit of a powerful warning. Just after the Nazi takeover, in spring 1933, she had been arrested while researching materials on anti-Semitism for the German Zionist Organisation at Berlin’s Prussian State Library. Her apartment was searched; both she and her mother were locked up briefly, then released. They fled, without stopping to arrange travel documents. They crossed to Czechoslovakia (then still safe) by a method that sounds almost too fabulous to be true: a sympathetic German family on the border had a house with its front door in Germany and its back door in Czechoslovakia. The family would invite people for dinner, then let them leave through the back door at night.

As Sartre argued in his 1943 review of The Stranger, basic phenomenological principles show that experience comes to us already charged with significance. A piano sonata is a melancholy evocation of longing. If I watch a soccer match, I see it as a soccer match, not as a meaningless scene in which a number of people run around taking turns to apply their lower limbs to a spherical object. If the latter is what I’m seeing, then I am not watching some more essential, truer version of soccer; I am failing to watch it properly as soccer at all.

Much as they liked Camus personally, neither Sartre nor Beauvoir accepted his vision of absurdity. For them, life is not absurd, even when viewed on a cosmic scale, and nothing can be gained by saying it is. Life for them is full of real meaning, although that meaning emerges differently for each of us.

For Sartre, we show bad faith whenever we portray ourselves as passive creations of our race, class, job, history, nation, family, heredity, childhood influences, events, or even hidden drives in our subconscious which we claim are out of our control. It is not that such factors are unimportant: class and race, in particular, he acknowledged as powerful forces in people’s lives, and Simone de Beauvoir would soon add gender to that list.

Sartre takes his argument to an extreme point by asserting that even war, imprisonment or the prospect of imminent death cannot take away my existential freedom. They form part of my ‘situation’, and this may be an extreme and intolerable situation, but it still provides only a context for whatever I choose to do next. If I am about to die, I can decide how to face that death. Sartre here resurrects the ancient Stoic idea that I may not choose what happens to me, but I can choose what to make of it, spiritually speaking.

But the Stoics cultivated indifference in the face of terrible events, whereas Sartre thought we should remain passionately, even furiously engaged with what happens to us and with what we can achieve. We should not expect freedom to be anything less than fiendishly difficult.

Freedom does not mean entirely unconstrained movement, and it certainly does not mean acting randomly. We often mistake the very things that enable us to be free — context, meaning, facticity, situation, a general direction in our lives — for things that define us and take away our freedom. It is only with all of these that we can be free in a real sense.

Nor did he mean that privileged groups have the right to pontificate to the poor and downtrodden about the need to ‘take responsibility’ for themselves. That would be a grotesque misreading of Sartre’s point, since his sympathy in any encounter always lay with the more oppressed side. But for each of us — for me — to be in good faith means not making excuses for myself.

Camus’ novel gives us a deliberately understated vision of heroism and decisive action compared to those of Sartre and Beauvoir. One can only do so much. It can look like defeatism, but it shows a more realistic perception of what it takes to actually accomplish difficult tasks like liberating one’s country.

Camus just kept returning to his core principle: no torture, no killing — at least not with state approval. Beauvoir and Sartre believed they were taking a more subtle and more realistic view. If asked why a couple of innocuous philosophers had suddenly become so harsh, they would have said it was because the war had changed them in profound ways. It had shown them that one’s duties to humanity could be more complicated than they seemed. ‘The war really divided my life in two,’ Sartre said later.

Poets and artists ‘let things be’, but they also let things come out and show themselves. They help to ease things into ‘unconcealment’ (Unverborgenheit), which is Heidegger’s rendition of the Greek term alētheia, usually translated as ‘truth’. This is a deeper kind of truth than the mere correspondence of a statement to reality, as when we say ‘The cat is on the mat’ and point to a mat with a cat on it. Long before we can do this, both cat and mat must ‘stand forth out of concealedness’. They must un-hide themselves.

Heidegger does not use the word ‘consciousness’ here because — as with his earlier work — he is trying to make us think in a radically different way about ourselves. We are not to think of the mind as an empty cavern, or as a container filled with representations of things. We are not even supposed to think of it as firing off arrows of intentional ‘aboutness’, as in the earlier phenomenology of Brentano. Instead, Heidegger draws us into the depths of his Schwarzwald, and asks us to imagine a gap with sunlight filtering in. We remain in the forest, but we provide a relatively open spot where other beings can bask for a moment. If we did not do this, everything would remain in the thickets, hidden even to itself.

The astronomer Carl Sagan began his 1980 television series Cosmos by saying that human beings, though made of the same stuff as the stars, are conscious and are therefore ‘a way for the cosmos to know itself’. Merleau-Ponty similarly quoted his favourite painter Cézanne as saying, ‘The landscape thinks itself in me, and I am its consciousness.’ This is something like what Heidegger thinks humanity contributes to the earth. We are not made of spiritual nothingness; we are part of Being, but we also bring something unique with us. It is not much: a little open space, perhaps with a path and a bench like the one the young Heidegger used to sit on to do his homework. But through us, the miracle occurs.

Beauty aside, Heidegger’s late writing can also be troubling, with its increasingly mystical notion of what it is to be human. If one speaks of a human being mainly as an open space or a clearing, or a means of ‘letting beings be’ and dwelling poetically on the earth, then one doesn’t seem to be talking about any recognisable person. The old Dasein has become less human than ever. It is now a forestry feature.

Even today, Jaspers, the dedicated communicator, is far less widely read than Heidegger, who has influenced architects, social theorists, critics, psychologists, artists, film-makers, environmental activists, and innumerable students and enthusiasts — including the later deconstructionist and post-structuralist schools, which took their starting point from his late thinking. Having spent the late 1940s as an outsider and then been rehabilitated, Heidegger became the overwhelming presence in university philosophy all over the European continent from then on.

As Levinas reflected on this experience, it helped to lead him to a philosophy that was essentially ethical, rather than ontological like Heidegger’s. He developed his ideas from the work of Jewish theologian Martin Buber, whose I and Thou in 1923 had distinguished between my relationship with an impersonal ‘it’ or ‘them’, and the direct personal encounter I have with a ‘you’. Levinas took it further: when I encounter you, we normally meet face-to-face, and it is through your face that you, as another person, can make ethical demands on me. This is very different from Heidegger’s Mitsein or Being-with, which suggests a group of people standing alongside one another, shoulder to shoulder as if in solidarity — perhaps as a unified nation or Volk.

For Levinas, we literally face each other, one individual at a time, and that relationship becomes one of communication and moral expectation. We do not merge; we respond to one another. Instead of being co-opted into playing some role in my personal drama of authenticity, you look me in the eyes — and you remain Other. You remain you.

This relationship is more fundamental than the self, more fundamental than consciousness, more fundamental even than Being — and it brings an unavoidable ethical obligation. Ever since Husserl, phenomenologists and existentialists had being trying to stretch the definition of existence to incorporate our social lives and relationships. Levinas did more: he turned philosophy around entirely so that these relationships were the foundation of our existence, not an extension of it.

Her last work, The Need for Roots, argues, among other things, that none of us has rights, but each one of us has a near-infinite degree of duty and obligation to the other. Whatever the underlying cause of her death — and anorexia nervosa seems to have been involved — no one could deny that she lived out her philosophy with total commitment. Of all the lives touched on in this book, hers is surely the most profound and challenging application of Iris Murdoch’s notion that a philosophy can be ‘inhabited’.

Other thinkers took radical ethical turns during the war years. The most extreme was Simone Weil, who actually tried to live by the principle of putting other people’s ethical demands first. Having returned to France after her travels through Germany in 1932, she had worked in a factory so as to experience the degrading nature of such work for herself. When France fell in 1940, her family fled to Marseilles (against her protests), and later to the US and to Britain. Even in exile, Weil made extraordinary sacrifices. If there were people in the world who could not sleep in a bed, she would not do so either, so she slept on the floor.

The mystery tradition had roots in Kierkegaard’s ‘leap of faith’. It owed much to the other great nineteenth-century mystic of the impossible, Dostoevsky, and to older theological notions. But it also grew from the protracted trauma that was the first half of the twentieth century. Since 1914, and especially since 1939, people in Europe and elsewhere had come to the realisation that we cannot fully know or trust ourselves; that we have no excuses or explanations for what we do — and yet that we must ground our existence and relationships on something firm, because otherwise we cannot survive.

One striking link between these radical ethical thinkers, all on the fringes of our main story, is that they had religious faith. They also granted a special role to the notion of ‘mystery’ — that which cannot be known, calculated or understood, especially when it concerns our relationships with each other. Heidegger was different from them, since he rejected the religion he grew up with and had no real interest in ethics — probably as a consequence of his having no real interest in the human.

Meanwhile, the Christian existentialist Gabriel Marcel was also still arguing, as he had since the 1930s, that ethics trumps everything else in philosophy and that our duty to each other is so great as to play the role of a transcendent ‘mystery’. He too had been led to this position partly by a wartime experience: during the First World War he had worked for the Red Cross’ Information Service, with the unenviable job of answering relatives’ inquiries about missing soldiers. Whenever news came, he passed it on, and usually it was not good. As Marcel later said, this task permanently inoculated him against warmongering rhetoric of any kind, and it made him aware of the power of what is unknown in our lives.

As the play’s much-quoted and frequently misunderstood final line has it: ‘Hell is other people.’ Sartre later explained that he did not mean to say that other people were hellish in general. He meant that after death we become frozen in their view, unable any longer to fend off their interpretation. In life, we can still do something to manage the impression we make; in death, this freedom goes and we are left entombed in other’s people’s memories and perceptions.

We have to do two near-impossible things at once: understand ourselves as limited by circumstances, and yet continue to pursue our projects as though we are truly in control. In Beauvoir’s view, existentialism is the philosophy that best enables us to do this, because it concerns itself so deeply with both freedom and contingency. It acknowledges the radical and terrifying scope of our freedom in life, but also the concrete influences that other philosophies tend to ignore: history, the body, social relationships and the environment.

The aspects of our existence that limit us, Merleau-Ponty says, are the very same ones that bind us to the world and give us scope for action and perception. They make us what we are. Sartre acknowledged the need for this trade-off, but he found it more painful to accept. Everything in him longed to be free of bonds, of impediments and limitations

Of course we have to learn this skill of interpreting and anticipating the world, and this happens in early childhood, which is why Merleau-Ponty thought child psychology was essential to philosophy. This is an extraordinary insight. Apart from Rousseau, very few philosophers before him had taken childhood seriously; most wrote as though all human experience were that of a fully conscious, rational, verbal adult who has been dropped into this world from the sky — perhaps by a stork.

For Merleau-Ponty, we cannot understand our experience if we don’t think of ourselves in part as overgrown babies. We fall for optical illusions because we once learned to see the world in terms of shapes, objects and things relevant to our own interests. Our first perceptions came to us in tandem with our first active experiments in observing the world and reaching out to explore it, and are still linked with those experiences.

Another factor in all of this, for Merleau-Ponty, is our social existence: we cannot thrive without others, or not for long, and we need this especially in early life. This makes solipsistic speculation about the reality of others ridiculous; we could never engage in such speculation if we hadn’t already been formed by them.

As Descartes could have said (but didn’t), ‘I think, therefore other people exist.’ We grow up with people playing with us, pointing things out, talking, listening, and getting us used to reading emotions and movements; this is how we become capable, reflective, smoothly integrated beings.

In general, Merleau-Ponty thinks human experience only makes sense if we abandon philosophy’s time-honoured habit of starting with a solitary, capsule-like, immobile adult self, isolated from its body and world, which must then be connected up again — adding each element around it as though adding clothing to a doll. Instead, for him, we slide from the womb to the birth canal to an equally close and total immersion in the world. That immersion continues as long as we live, although we may also cultivate the art of partially withdrawing from time to time when we want to think or daydream.

When he looks for his own metaphor to describe how he sees consciousness, he comes up with a beautiful one: consciousness, he suggests, is like a ‘fold’ in the world, as though someone had crumpled a piece of cloth to make a little nest or hollow. It stays for a while, before eventually being unfolded and smoothed away. There is something seductive, even erotic, in this idea of my conscious self as an improvised pouch in the cloth of the world. I still have my privacy — my withdrawing room. But I am part of the world’s fabric, and I remain formed out of it for as long as I am here.

By the time of these works, Merleau-Ponty is taking his desire to describe experience to the outer limits of what language can convey. Just as with the late Husserl or Heidegger, or Sartre in his Flaubert book, we see a philosopher venturing so far from shore that we can barely follow. Emmanuel Levinas would head out to the fringes too, eventually becoming incomprehensible to all but his most patient initiates.

Sartre once remarked — speaking of a disagreement they had about Husserl in 1941 — that ‘we discovered, astounded, that our conflicts had, at times, stemmed from our childhood, or went back to the elementary differences of our two organisms’. Merleau-Ponty also said in an interview that Sartre’s work seemed strange to him, not because of philosophical differences, but because of a certain ‘register of feeling’, especially in Nausea, that he could not share. Their difference was one of temperament and of the whole way the world presented itself to them.

The two also differed in their purpose. When Sartre writes about the body or other aspects of experience, he generally does it in order to make a different point. He expertly evokes the grace of his café waiter, gliding between the tables, bending at an angle just so, steering the drink-laden tray through the air on the tips of his fingers — but he does it all in order to illustrate his ideas about bad faith. When Merleau-Ponty writes about skilled and graceful movement, the movement itself is his point. This is the thing he wants to understand.

We can never move definitively from ignorance to certainty, for the thread of the inquiry will constantly lead us back to ignorance again. This is the most attractive description of philosophy I’ve ever read, and the best argument for why it is worth doing, even (or especially) when it takes us no distance at all from our starting point.

By prioritising perception, the body, social life and childhood development, Merleau-Ponty gathered up philosophy’s far-flung outsider subjects and brought them in to occupy the centre of his thought.

In his inaugural lecture at the Collège de France on 15 January 1953, published as In Praise of Philosophy, he said that philosophers should concern themselves above all with whatever is ambiguous in our experience. At the same time, they should think clearly about these ambiguities, using reason and science. Thus, he said, ‘The philosopher is marked by the distinguishing trait that he possesses inseparably the taste for evidence and the feeling for ambiguity.’ A constant movement is required between these two

As Sartre wrote in response to Hiroshima, humanity had now gained the power to wipe itself out, and must decide every single day that it wanted to live. Camus also wrote that humanity faced the task of choosing between collective suicide and a more intelligent use of its technology — ‘between hell and reason’. After 1945, there seemed little reason to trust in humanity’s ability to choose well.

Merleau-Ponty observed in a lecture of 1951 that, more than any previous century, the twentieth century had reminded people how ‘contingent’ their lives were — how at the mercy of historical events and other changes that they could not control. This feeling went on long after the war ended. After the A-bombs were dropped on Hiroshima and Nagasaki, many feared that a Third World War would not be long in coming, this time between the Soviet Union and the United States.

Like all animal brains, human brains are not general-purpose universal learning machines, but, instead, are intricately structured suites of instincts optimized for the environments in which they evolved. To harness our brains, we want to let the brain’s brilliant mechanisms run as intended—i.e., not to be twisted. Rather, the strategy is to twist Y into a shape that the brain does know how to process.

there is a very good reason to be optimistic that the next stage of human will come via the form of adaptive harnessing, rather than direct technological enhancement: It has already happened. We have already been transformed via harnessing beyond what we once were. We’re already Human 2.0, not the Human 1.0, or Homo sapiens, that natural selection made us. We Human 2.0’s have, among many powers, three that are central to who we take ourselves to be today: writing, speech, and music (the latter perhaps being the pinnacle of the arts). Yet these three capabilities, despite having all the hallmarks of design, were not a result of natural selection, nor were they the result of genetic engineering or cybernetic enhancement to our brains. Instead, and as I argue in both The Vision Revolution and my forthcoming Harnessed, these are powers we acquired by virtue of harnessing, or neuronal recycling.

Although the step from Human 1.0 to 2.0 was via cultural selection, not via explicit human designers, does the transformation to Human 3.0 need to be entirely due to a process like cultural evolution, or might we have any hope of purposely guiding our transformation? When considering our future, that’s probably the most relevant question we should be asking ourselves.

One of my reasons for optimism is that nature-harnessing technologies (like writing, speech, and music) must mimic fundamental ecological features in nature, and that is a much easier task for scientists to tackle than emulating the exhorbitantly complex mechanisms of the brain

Stimuli are involuntarily being compared and contrasted with previous experiences. For example, when you see when you see stop light change from red to green, your mind perceives this change in colour, not so much as a change in colour, but more as a signal to move forward.

What we perceive depends on what is important and interest in at the time for each person (Cultural Influences on Perception). Our perceptions and conceptions are affected by things such as biases, motivations emotions cultural perspectives interests, expectations and background experiences (existing knowledge)

Optical illusions are very popular with students just starting out in ToK. They are clear evidence that we have weaknesses in terms of how our mind interprets stimuli. Often things are not as they appear. Our previous experiences with similar stimulai impairs our perception.