We assume the information our senses feed us is objective — of course we do, because what else do we have to go on? There is something almost vertiginous, then, about Ed Yong’s new book, An Immense World: How Animal Senses Reveal the Hidden Realms Around Us, which confronts exactly how we perceive what we perceive. “Light is just electromagnetic radiation,” he says. “Sound is just waves of pressure. Smells are just small molecules. It’s not obvious that we should be able to detect any of these,” let alone that they should produce the particular subjective experiences that they do.

Your experience of a beach — the turquoise sea, the warmth of the sun, the screeching gull — isn’t what the beach is. The “real” beach is giving off all sorts of stimuli, only some of which a human brain uses to form a mental representation of its surroundings. There are many, many more stimuli that we cannot sense or even imagine sensing. But other species can.

Take the seabirds on the beach, for instance. Many seabird species are finely attuned to the scent of chemicals that give away the presence of the krill they eat, meaning that far from a flat, featureless expanse, the ocean’s surface has “a secret topography” of “odorous mountains and unscented valleys… invisible to the eye but evident to the nose”. Others are able to sense the Earth’s magnetic field, which guides them during migrations. And almost all birds can discriminate between “millions” of colours that humans are unable to imagine — to them, we are colourblind.

Some of the senses Yong details are delightfully surreal. A dolphin is effectively a “living medical scanner”: echolocation allows them to “perceive your lungs and skeleton… shrapnel in war veterans and foetuses in pregnant women”. Incredibly, beaked whales, which also echolocate, have “a strange assortment of crests, ridges, and bumps” on their skulls, which might be a form of “internal antlers” that could allow them to signal to others while retaining a sleek, hydrodynamic form.

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What these alien senses might feel like, we can only guess. Philosophers have long grappled with this problem of subjectivity. Thomas Nagel, in his 1974 essay What Is It Like to Be A Bat?, argued that it is impossible to capture the experience of one sense by analogy to another: for example, “red is like the sound of a trumpet”. “That should be clear to anyone who has both heard a trumpet and seen red,” he wrote. It may be tempting to talk about dolphins “seeing” the inside of each others’ bodies, but in reality, it’s possible that what they experience via their sonar sense may be so different that trying to imagine it as a kind of “seeing” is as futile as describing the colour red in terms of its musical qualities.

Similarly, images meant to show us how ultraviolet looks to the many animals that can see it often render it as a kind of glowing purple. But to birds and bees, ultraviolet is an entirely different colour, one that no human eye has ever seen. These images are chasing the same impossible dream of children who try to invent a new colour by mixing their felt-tips. The only way for humans to see an entirely new colour, as different to our existing palette as red is from blue, would be to evolve a new colour receptor.

The biological term for these unique perceptual landscapes belonging to different species is Umwelten — German for “environments” — in this case meaning not just an animal’s physical environment but the environment as it appears to that animal. The Earth’s magnetic field is not part of our Umwelt as humans — it’s there, but we don’t sense it. A barnacle might exist on the same beach as us, but is oblivious to the peachy clouds in the sky as the sun sets: it lacks the capacity to perceive them. They are not part of its Umwelt.

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The German zoologist Jakob von Uexküll, Yong tells us, coined this usage of Umwelt in 1909, comparing an animal’s body to a house “with a number of windows… a light window, a sound window, an olfactory window, a taste window, and a great number of tactile windows”. It is totally impossible for a mind inside the house to gain information about the outside world except via its windows; from vantage points in different houses, with windows made from different materials or placed at different angles, the same view would appear totally different.

Except, of course, we cannot switch vantage points. Every conscious being is permanently and inevitably stuck inside its own lonely house, through which all experience of the outside world is filtered; all communication with other minds must pass through the windows of their own houses before it can reach them. Our windows aren’t just limited by our bodies and physical senses, but also by our culture and past experiences. I can guess but I can never know what it would be like to have been born blind instead of sighted, or male instead of female, or in Tokyo instead of in London.

I am moderately high in neuroticism: one of the “big five” personality traits that describes a person’s tendency to worry and ruminate. Speaking to (mostly male) friends who are much lower in neuroticism (women are significantly more neurotic than men, on average), I am struck by how alien both ways of thinking are to each other: to have an inner monologue that points out hundreds of possible but unlikely hazards every day, or to be someone to whom these thoughts would never occur. How many more features of our temperaments and histories must there be that give each individual an inescapably different perspective on the same experience?

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Nowhere is this more apparent than in today’s culture wars, when political opponents seem to inhabit entirely separate realities. Despite living through the same pandemic, those who think face masks in schools are a form of child abuse appear to be living on another planet from those who don’t allow their teenagers to leave the house for fear of long Covid. This is true, in a sense: we are all living in our own private Umwelten, with a slightly different view of the world filtering in through our unique windows. Perhaps the surprising thing, in a way, is that there’s so much agreement.

A century ago, we knew far less about the sensory capabilities of animals. Bat echolocation, dolphin sonar, and bird magnetoreception were all unknown — barely even guessed at — before the 20th century. These discoveries are testament to the awe-inspiring power of science, but they are also a much-needed dose of humility, reminding us of how much is out there beyond our perceptions. We hear a lot about the need to understand and defeat our “cognitive biases” — but in reality, our biases can never be escaped. They are our only window to the Immense World outside our own minds, whose full form remains permanently and tantalisingly out of our grasp.

When I started on this course, I was seldom challenged. I was asked to make a radio programme about the changing face of ethnic minority politics in 2011 and no one then thought to question my right to do so because of my colour.

For better or worse, this would be far less likely to happen today. I have just been appointed to an official body concerned with combating discrimination of many kinds, none of which I will ever experience myself. Some people complained that my background renders me incapable of doing the job properly.

I hope to prove those doubters wrong, but there is a serious point here. Personal experience is, of course, very important in shaping one’s views. To take a topical example, I notice that friends who have had a bad dose of Covid-19 tend to be more supportive of tough lockdown measures than friends who have not had it at all or only lightly.

Personal experience is a kind of knowledge. But it is also highly constrained and even misleading, that’s why accusing someone of being anecdotal is usually an insult in an argument. Your own experience is one part of the truth but usually quite a small one.

When we are talking about big abstract things, like society or the economy we would not get very far just basing things on our own direct experience. We need facts, reliable data, objective things which can give us a handle on the bigger picture. We may then select the data based on our own interests or worldview — indeed it is almost impossible not to — but at least we are making some effort to use the apparatus of objectivity: logic and evidence.

Our knowledge of the world is usually some sort of balance between personal experience and abstract ideas. And it is my contention,  perhaps not a very original one, that in recent years the balance has been tipping away from the realm of the objective towards personal experience.

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To repeat, that is not always a bad thing. One of the reasons we want our institutions to be at least somewhat representative of our society is that we recognise the importance of different experiences of the world: female, gay, ethnic minority and so on. And making it easier for people, especially from previously unheard groups, to speak for themselves rather than be spoken for, is self-evidently a step forward.

I have just written a book called Head, Hand, Heart which argues, among other things, that those with a certain kind of academic/analytical intelligence have been too dominant in our institutions and that we need more space for other aptitudes, intelligences and experiences.

But the focus on the primacy of subjective experience, and the authority that it is thought to bestow, can also go too far. At its most extreme it might call into question much of art and literature. Can, for example, the female writer Taffy Brodesser-Akner write truthfully about the sex life of the male lead character in her novel Fleishman is in Trouble?

That may seem like a silly example, after all, if she couldn’t plausibly get inside a man’s head, no one would have bought her best-seller. Yet quite extreme subjectivism is on the march. Consider America’s current polarisation with pro and anti-Trump forces having not only different opinions but selecting different facts about the world to fit their experiences.

The identity politics Left also often prioritises experience over data. Indeed, identity politics is partly based on the authority of who it is that is saying something, rather than what they are saying. And this is not a fringe phenomenon: the BBC’s new guidelines on racist language ask the reporter to consider who is saying the words.

The other source of this new bias towards individual experience as the source of knowledge and authority is surely social media. The new forms of public communication have dispatched the old gate keepers of the elite media, and given everyone who wants it access to the public square. Now conspiracy theories seem to compete on almost equal terms with well-established facts in an information free for all.

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The personal experience bias of social media has also seeped back into more traditional forms of media. The stiff, but authoritative, news programmes of my youth have given way to news that is much more focused on emotion and human interest, something all too evident at the height of the pandemic.

And our schools are not immune either. I was recently invited to speak about the Black Lives Matter movement to the sixth form of a girls’ private school in north London. I made what I think of as the liberal case for scepticism about two big assumptions associated with BLM, first that little has changed for black people in the last 40 years and second that claiming all white people are privileged by their race is a helpful way to promote race equality.

I cited lots of facts about the advance of black people and other minorities in education and employment, including into elite professional jobs — minority Brits now have higher representation in the top social class than white ones. I pointed to the private school itself — about half-white, half-Asian — as evidence of Britain’s relative openness. This did not go down well.

Afterwards a group of girls came up to me and told me about their experiences of racism in everyday life. It is true that the kind of micro-aggressions they were talking about are hard to capture or quantify in objective data. And for them, their bad experiences swamped my statistics of success and they felt by giving priority to those aggregate facts I was showing insufficient respect to their individual plights.

For someone like me, with privilege and power, to be challenged on these issues is obviously perfectly healthy, and if it makes me feel uncomfortable well that’s my own little First World problem. But too much subjectivism is also contributing to a less mature political conversation. Just as cleaving too exclusively to “the data” can produce a sort of blindness about human emotion (remember the Remain campaign’s focus on a dry cost-benefit analysis?), so, allowing your own personal experience to loom too large leads to a sort of equal and opposite blinkeredness, maybe excusable in 17-year-old students.

By chance I had an appointment with my mixed-race physiotherapist the same day as my sixth form talk. It turns out he is involved with a small group called the Cultural Health Club who are trying to make their profession more diversity-friendly. I asked what the problem was, and he said that physiotherapy was very white and middle class. I replied that this is a majority white middle-class country so that is hardly a surprise. No, he said, but did I realise that only 3% of physios were black? I did not realise that, but did he realise that according to the census only just over 3% of the UK population is black (meaning of black Caribbean or black African heritage). No, he had not realised that.

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He took my point in his stride and asked me to send the relevant statistics. He lives in a majority-minority part of London where it is easy to assume that the black population of the country is much higher than it actually is. I use this example not to challenge or belittle his reality — he told me of a horrible experience of being rejected by a patient because of his race — but to suggest that in democratic argument subjective experience needs to be combined with some knowledge of the bigger picture.

That ought to include knowledge of the basic facts of UK demography and perhaps also of the huge range in minority outcomes and experiences and, indeed, of views. A recent YouGov poll found ethnic minority Brits split down the middle on whether race has had an impact on their ability to succeed.

So, we all see the world somewhat differently but there are also shared perceptions that apply to particular groups, though even they tend not to be homogeneous as we have just seen.

And the subjective individual experience of someone does not necessarily tell us much about the average experience of someone from that group. To take a trivial personal example, I’m unusually tall and that means that I experience the world somewhat differently from a man of average height. But the fact that I’m prone to knock my head on doorways doesn’t mean the country as a whole needs to adjust the height of the typical doorway.

(I do not imply by that example — as some critics suggested when I used it in a BBC Radio Four essay — that we should defund support for better disabled access!)

To try to understand the experiences of others, to walk in others’ shoes, is clearly desirable. And this applies especially to those whose experiences are untypical and a source of pain and suffering.

Some untypical experiences require public policy responses, others do not, obviously. We can leave those doorways that I have to stoop to get through where they are. Yet where does all this leave the wider argument?

Maybe one should not think of the subjective-objective as on a spectrum from personal truth to aggregate truth with the latter a higher form of truth than the former. Rather they exist on different planes, to some extent incommensurate. They both tell us different things about human experience and are both valuable in different contexts.

Meanwhile, the world is still coming to terms with the radical upending of our public information and communication systems. Elites have lost a lot of narrative control, to no one in particular. And the space for the objective stuff has been diminished, partly replaced by personal experience and emotion. That is not all bad but it seems to be making it harder to come to democratic compromises. And if a growing number of us come to believe that individual experience and perception is the primary truth then it just becomes your truth versus mine and we are all, like Fleishman, truly in trouble.

This is an edited version of an essay for BBC Radio 4’s  ‘A Point of View‘