Of Trees Falling in the Forest

On the anthropocentrism of philosophy

"If a tree falls in the forest and no one is around to hear it fall, does it make a sound?" Despite the seeming profundity of this question, and despite its use in philosophical discussions and philosophy textbooks, it is really quite silly and is in fact obsolete as a philosophical issue in the 21st century. What is wrong with the question is that it frames the issue in false terms. It makes it sound as if the tree is conscious (in the sense that humans are conscious) and is able to detect the presence of humans; the tree decides whether to make a sound or not; and it follows the rule: When there is a someone around, make a sound when you fall; when there isn't anyone around, don't make a sound. The question makes the phenomenon of sound into something like the equivalent of an arboreal fart that the tree holds in or lets out at will depending on the social circumstances: Fart when you are alone or with your wife, but don't fart in the presence of company. Expressed in this way, the question can be seen for the nonsense that it really is. To get out of this corner, some "philosophers" resort to the "semantics" expedient and say that it all depends on how we define the term "sound." If we define sound as the effect of certain fluctuations of air pressure on the tympanum of the human ear, which sends signals to the brain where they are interpreted in a certain way, then the answer is "No." However, a little reflection will show that the question is still absurd. If sound in defined in this way, then it is not something that the tree "makes" but something that is created in the brain. It is impossible to talk of a tree making a sound, if by "sound" we are referring to the effect of certain physical phenomena on our sense of hearing. If by definition sound consists in the act of reception, then we make the sound, not the tree. Of course, from a scientific point of view, it is nonsensical to define sound as the act of reception. Science has long know that there are sound frequencies beyond the limits of the human capacity to receive. One might ask: If someone blows a dog whistle and there are no dogs around to hear it, does it make a sound? This, of course, would be a truly nonsensical question in science. Similarly, one might ask whether bats make sounds, since humans do not hear them. Today we understand the "mechanics" of sound fairly well and there is little doubt as to its nature and how it is produced. We know that sound is not something that happens in our ears or our brains: it is merely the perturbation of air. Sometimes these perturbations have no effect on our ears, or if they do, our brain is unable to process the effect in any meaningful way. Thus, the phenomenon is in the air, not in our ears. Let us imagine that there is a large crowd of people gathered in the forest, and that there is a given tree that the people are watching. Let us further imagine that this tree is enclosed in a giant glass dome from which all the air has been sucked out to create a perfect vacuum (and let us also imagine that trees, or this tree in particular, can survive in a vacuum). Now let us imagine that we somehow contrive to make the tree fall. There are plenty of people around to hear the sound of the tree falling. But does it make a sound? Of course not! This "thought experiment" should be sufficient to debunk forever any notion that sound is a human construct and requires the presence of humans (or living creatures). That idea comes from the heady anthropocentric philosophies of the Age of Reason, when man became the measure of all things and everything in the universe was understood from the reference point of the only creature capable of "reason." That intoxicating anthropocentrism was nowhere more eloquently expressed than in the following lines written by the English poet Thomas Gray (1716-1771): Full many a gem of purest ray serene The dark unfathomed caves of ocean bear: Full many a flower is born to blush unseen, And waste its sweetness on the desert air. —"Elegy Written in a Country Churchyard" (1750) The idea here is that if humans are not present to witness and appreciate the beauty of nature, it is wasted. This, of course, is sheer arrogance, since man has been around for a mere fraction of the time that gems and flowers—and trees falling in the forest—have been around. It is time for philosophy to shed the obsolete thought patterns of the past and catch up to science. Philosophy today needs to direct its energies to more fruitful lines of inquiry. One way to start is to frame the issue in more meaningful terms: How does the human perception of sound shape our understanding of the world around us and our place in the universe?

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Hold your breath at Marble Arch!

Air pollution up to five times over the EU limit in Central London hotspots

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  • Dirty air is an invisible killer, but an effective one.
  • A recent study estimates that more than 9,000 people die prematurely in London each year due to air pollution.
  • This map visualises the worst places to breathe in Central London.

The Great Smog of 1952

London used to be famous for its 'pea-soupers': combinations of smoke and fog caused by burning coal for power and heating.

All that changed after the Great Smog of 1952, when weather conditions created a particularly dense and persistent layer of pollution. For a number of days, visibility was reduced to as little as one foot, making traffic impossible. The fog even crept indoors, leading to cancellations of theatre and film showings. The episode wasn't just disruptive and disturbing, but also deadly: according to one estimate, it directly and indirectly killed up to 12,000 Londoners.

Invisible, but still deadly

Image: MONEY SHARMA/AFP/Getty Images

London Mayor Sadiq Khan

After the shock of the Great Smog, the UK cleaned up its act, legislating to replace open coal fires with less polluting alternatives. London Mayor Sadiq Khan is hoping for a repeat of the movement that eradicated London's smog epidemic, but now for its invisible variety.

The air in London is "filthy, toxic", says Khan. In fact, poor air quality in the British capital is a "public health crisis". The city's poor air quality is linked not just to thousands of premature deaths each year, but also to a range of illnesses including asthma, heart disease and dementia. Children growing up in areas with high levels of air pollution may develop stunted lungs, with up to 10% less capacity than normal.

Image: Transport for London

ULEZ phases 1 and 2, and LEZ

Khan has led a very active campaign for better air quality since his election as London Mayor in 2016. Some of the measures recently decided:

  • Transport for London has introduced 2,600 diesel-electric hybrid buses, which is said to reduce emissions by up to 40%.
  • Mr Khan has pledged to spend £800 million on air quality over a five-year period.
  • Uber fares will rise by 15p (20¢) to help drivers buy electric cars.
  • Since the start of 2018, all new single-decker buses are zero-emission and all new taxis must be hybrid or electric.
  • Mr Khan has added a T-charge on the most toxic vehicles entering the city. On 8 April, the T-charge will be replaced by an Ultra-Low Emission Zone (ULEZ), contiguous with the Congestion Charge Zone.
  • The ULEZ is designed to reduce emissions of nitrogen oxide and particulate matter by charging vehicles who don't meet stringent exhaust emission standards.
  • By October 2020, a Low-Emission Zone (LEZ), applicable to heavy commercial vehicles, will cover most of Greater London.
  • By October 2021, the ULEZ will expand to cover a greater part of Central London.

Central London's worst places for breathing

Image: Steven Bernard / Financial Times

Heathrow (bottom left on the overview map) is another pollution hotspot

What worries experts is that despite considerable efforts already made, levels of air pollution stubbornly refuse to recede – and remain alarmingly high in locations where traffic flows converge.

It's not something you'd think of, given our atmosphere's fluctuating nature, but air pollution hotspots can be extremely local – as this map demonstrates.

One important lesson for all Londoners: don't inhale at Marble Arch! Levels of nitrogen dioxide (NO2) are five times the EU norm – the highest in the city. Traffic permitting, quickly cross Cumberland Gate to Speakers' Corner and further into Hyde Park, where levels sink back to a 'permissible' 40 milligrams per cubic meter. Now you can inhale!

Almost as bad: Tower Hill (4.6 times the EU norm) and Marylebone Road (4 times; go to nearby Regent's Park for relief).

Also quite bad: the Strand (3.9), Piccadilly Circus (3.8), and Hyde Park Corner (also 3.8), Victoria (3.7) and Knightsbridge (3.5), the dirty trio just south of Hyde Park.

Elephant & Castle is the only pollution hotspot below the Thames and, perhaps because it's relatively isolated from other black spots, also the one with the lowest multiplication factor (2.8 times the maximum level).

On the larger map, the whole of Central London, including its relatively NO2-free parks, still shows up as more polluted than the outlying areas. Two exceptions flare up red: busy traffic arteries; and Heathrow Airport (in the bottom left corner).

Image: Mike Malone, CC BY SA 4.0

Traffic congestion on London's Great Portland Street

So why is Central London's air pollution problem so persistent? In part, this is because the need for individual transport in cars seems to be inelastic. For example, the Congestion Charge has slashed the number of vehicles entering Central London by 30%, but the number of (CC-exempt) private-hire vehicles entering that zone has quadrupled over the same period.

Cycling has really taken off in London. But despite all pro-cycling measures, a wide range of other transport options and car-dissuading measures, central London is still a very congested place. Average traffic speeds on weekdays has declined to 8 miles (13 km) per hour – fittingly medieval speeds, as the road network was largely designed in medieval times.

Narrow streets between high buildings, filled to capacity with slow-moving traffic are a textbook recipe for semi-permanent high levels air pollution.

The large share of diesel vehicles on London's streets only increases the problem. Diesel vehicles emit lower levels of carbon dioxide (CO2) than petrol cars, which is why their introduction was promoted by European governments.

However, diesels emit higher levels of the highly toxic nitrogen dioxide (NO2) than initial lab tests indicated. Which is why they're being phased out now.

As bad as Delhi, worse than New York

Image: Sanchit Khanna/Hindustan Times via Getty Images

By some measures, London's air quality is almost as bad as New Delhi's.

By some measures, especially NO2, London's air pollution is nearly as bad as big Asian cities such as Beijing or New Delhi, and much worse than other developed cities such as New York and Madrid.

The UK is bound to meet pollution limits as set down in the National Air Quality objectives and by EU directives, for example for particulate matter and nitrogen dioxide.

  • Particulate matter (PM2.5) consists of tiny particles less than 2.5 micrometres in diameter emitted by combustion engines. Exposure to PM2.5 raises the mortality risk of cardiovascular diseases. The target for PM2.5 by 2020 is 25 µg/m3. All of London currently scores higher, with most areas at double that level.
  • Mainly emitted by diesel engines, NO2 irritates the respiratory system and aggravates asthma and other pre-existing conditions. NO2 also reacts with other gases to form acid rain. The limit for NO2 is 40 µg/m3, and NO2 levels must not exceed 200 µg/m3 more than 18 times a year. Last year, London hit that figure before January was over.

Google joins fight against air pollution

Image: laszlo-photo, CC BY SA 2.0

Elephant & Castle, London.

Studies predict London's air pollution will remain above legal limits until 2025. Sadiq Khan – himself an asthma sufferer – is working to make London's air cleaner by measures great and small. Earlier this week, he announced that two of Google's Street View cars will be carrying air quality sensors when mapping the streets of London

Over the course of a year, the two cars will take air quality readings every 30 metres in order to identify areas of London with dangerous levels of air pollution that might be missed by the network of fixed sensors. An additional 100 of those fixed sensors will be installed near sensitive locations and known pollution hotspots, doubling the network's density.

It's all part of Breathe London, a scheme to map the British capital's air pollution in real time. Breathe London will be the world's largest air quality monitoring network, said Mr Khan, launching the scheme at Charlotte Sharman Primary School in the London borough of Southwark.

Up to 30% of the school's pupils are said to be asthma sufferers. Charlotte Sharman is close to Elephant & Castle, as the above map shows, one of Central London's air pollution hotspots.

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The most culturally chauvinist people in Europe? Greeks, new research suggests

Meanwhile, Spaniards are the least likely to say their culture is superior to others.

Image: Pew Research Center
Strange Maps
  • Survey by Pew Research Center shows great variation in chauvinism across Europe.
  • Eight most chauvinist countries are in the east, and include Russia.
  • British much more likely than French (and slightly more likely than Germans) to say their culture is "superior" to others.
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A 'vampire' fungus has killed millions of bats since 2006. Here's why it matters.

White-nose syndrome is nearly as lethal to bats as the Black Plague was for humans.

Photo by Igam Ogam on Unsplash
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  • White-nose syndrome has killed at least 6.7 million bats, though this estimate was made in 2012, and the current figure is almost certainly much higher.
  • Bats serve a crucial role in our ecosystem and economy, and white-nose syndrome is already pushing many species to the brink of extinction.
  • Researchers and scientists are working hard to develop novel methods to cure white-nose syndrome; a few methods have shown promise, but none have yet been deployed in the field.
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