Dear Ken and all,
Here is a sample of Terry, Ian and Jack's description of human centred
perspective from Science of the Discworld IV pp 24-34.
Happy reading,
Terry

snip==>

Interpretations matter, because 'the facts' seldom explain how the universe
relates to us. 'The facts' tell us that the Sun's heat comes from nuclear
reactions, mainly hydrogen fusing to helium. But we want more. We want to
know why. Did the Sun come into existence in order to provide us with heat?
Or is it the other way round: are we on this planet because the Sun's heat
provided an environment in which creatures like us could evolve? The facts
are the same either way, but their implications depend on how we interpret
them. 

Our default interpretation is to view the world in human terms. This is no
great surprise. If a cat has a point of view, it surely views the world in
feline terms. But humanity's natural mode of operation has had a profound
effect on how we think about our world, and on what kinds of explanation we
find convincing. It also has a profound effect on what world we think about.
Our brains perceive the world on a human scale, and interpret those
perceptions in terms of what is - or sometimes was - important to us. 

Our focus on the human scale may seem entirely reasonable. How else would we
view our world? But rhetorical questions deserve rhetorical answers, and for
us, unlike the rest of the animal kingdom, there are alternatives. The human
brain can consciously modify its own thought-patterns. We can teach
ourselves to think on other scales, both smaller and larger. We can train
ourselves to avoid psychological traps, such as believing what we want to
because we want to. We can think in even more alien ways: mathematicians
routinely contemplate spaces with more than three dimensions, shapes so
complicated that they have no meaningful volume, surfaces with only one
side, and different sizes of infinity. 

Humans can think inhuman thoughts. 

That kind of thinking is said to be analytic. It may not come naturally, and
its outcomes may not always be terribly comforting, but it's possible. It
has been the main path to today's world, in which analytic thinking has
become increasingly necessary for our survival. If you spend your time
comfortably telling yourself that the world is what you want it to be, you
will get some nasty surprises, and it may be too late to do anything about
them. 

Unfortunately, the need to think analytically places a huge barrier between
science and many human desires and beliefs that re-emerge in every
generation. Battles scientists fondly imagined were won in the nineteenth
century must continually be refought; rationality and evidence alone may not
be enough to prevail. 

There is a reason for our natural thought-patterns. They evolved, along with
us, because they had survival value. A million years ago, human ancestors
roamed the African savannahs, and their lives depended - day in, day out -
on finding enough food to keep them alive, and avoiding becoming food
themselves. The most important things in their lives were their fellow human
beings, the animals and plants that they ate, and the animals that wanted to
eat them. 

Their world also included many things that were not alive: rocks; rivers,
lakes and seas; the weather; fires (perhaps started by lightning); the Sun,
Moon and stars. But even these often seemed to share some of the features of
life. Many of them moved; some changed without any apparent pattern, as if
acting on their own impulses; and many could kill. So it is not surprising
that as human culture developed, we came to view our world as the outcome of
conscious actions by living entities. The Sun, Moon and stars were gods,
visible evidence for the existence of supernatural beings that lived in the
heavens. A rumble of thunder, a flash of lightning - these were signs of the
gods' displeasure. The evidence was all around us on a daily basis, which
put it beyond dispute. 

In particular animals and plants were central to the lives of early humans.
You only have to browse through a book of Egyptian hieroglyphs to notice
just how many of them are animals, birds, fish, or bits of animals, birds,
fish and plants. Egyptian gods were depicted with the heads of animals; in
one extreme case, the god Khepri, the head was an entire dung beetle, neatly
placed on top of an otherwise headless human body. Khepri was one aspect of
the Sun-god, and the dung beetle (or scarab) got in on the act because dung
beetles roll balls of dung around and dig them into the ground. Therefore
the Sun, a giant ball, is pushed around by a giant dung beetle; as proof,
the Sun also disappears into the ground (the underworld) every evening at
sunset. 

The physicist and science fiction author Gregory Benford has written many
essays with a common theme: broadly speaking, human styles of thought tend
to fall into two categories. One is to see humanity as the context for the
universe; the other is to see the universe as the context for humanity. The
same person can think both ways of course, but most of us tend to default to
one of them. Most ways to separate people into two kinds are nonsense: as
the old joke goes, there are two kinds of people: those who think there are
two kinds of people, and those who don't. But Benford's distinction is an
illuminating one, and it holds more than a grain of truth. 

We can paraphrase it like this. Manv people see the surrounding world  as a
resource for humans to exploit; they also see it as a reflection of
themselves. What matters most, in this view, is always 'What can this do for
me?' (or 'for us?) is the main, and often the only, question worth asking.
From such a viewpoint, to understand something is to express it in terms of
human agency. What matters is its purpose, and that is whatever we use it
for. In this worldview, rain exists in order to make crops grow and to
provide fresh water for us to drink. The Sun is there because it warms our
bodies. The universe was designed with us in mind, constructed so that we
could live in it, and it would have no meaning if we were not present. 

It is a short and natural step to see human beings as the pinnacle of
creation, rulers of the planet, masters of the universe. Moreover, you can
do all of that without any conscious recognition of how narrowly
human-centred your worldview is, and maintain that you are acting out of
humility, not arrogance, because of course we are subservient to the
universe's creator. Which is basically a superhuman version of us - a king,
an emperor, a pharaoh, a lord - whose powers are expanded to the limits of
our imagination. 

The alternative view is that human beings are just one tiny feature of a
vast cosmos, most of which does not function on a human scale or take any
notice of what we want. Crops grow because rain exists, but rain exists for
reasons that have virtually nothing to do with crops. Rain has been in
existence for billions of years, crops for about ten thousand. In the cosmic
scheme of things, human beings are just one tiny incidental detail on an
insignificant ball of rock, most of whose history happened before we turned
up to wonder what was going on. We may be the most important thing in the
universe as far as we are concerned, but nothing that happens outside our
tiny planet depends on our existence, with a few obvious exceptions like
various small but complicated bits of metal and plastic now littering the
surface of the Moon and Mars, in orbit around Mercury, Jupiter and Saturn,
or wandering through the outer edges of our solar system. We might say that
the universe is indifferent to us, but even that statement is too
self-conscious; it endows the universe with the human attribute of
indifference. There is no 'it' to be indifferent. The system of the world
does not function in human terms. 

We'll refer to these ways of thinking as 'human-centred' and
'universe-centred'. Many controversies that grab the headlines stem, to a
greater or lesser extent, from the deep differences between them. Instead of
assuming that one must be superior to the other, and ; then arguing
vehemently about which one it is, we should first learn to recognise the
difference. Both have advantages, in their proper spheres of influence. What
causes trouble is when they tread on each other's toes. 

Before the early twentieth century, scientists used to think that phenomena
like light could either be particles or waves, but not both. They argued -
often nastily - about which was correct. When quantum theory was invented,
it turned out that matter had both aspects, inseparably intertwined. At
about the time that all reputable scientists knew that light was a wave,
photons turned up, and those were particles of light. Electrons, which were
obviously particles when they were discovered, turned out to have wavelike
features as well. So quantum physicists got used to the idea that things
that seemed to be particles were actually tiny clumps of waves. 

Then quantum field theory came along, and the waves stopped being clumped.
They could spread out. So now particle physicists have to know about quantum
fields, and our best explanation of why 'particles' have mass is the
existence of an all-pervading Higgs field. On the other hand, the current
evidence only supports the existence of the particle-like aspect of this
field: the Higgs boson. The field itself has not been observed. It might not
exist, and that would be interesting, because it would overturn the way
physicists currently think about particles and fields. It would also be
somewhat annoying. 

In everyday life, we encounter solid, compact objects, such as rocks, and
they make it easy for us to think about tiny particles. We encounter sloshy
but well-defined structures that move around on water, and we feel
comfortable with waves. In a human-centred view, there are no sloshy rocks,
which makes us assume - almost without questioning it - that nothing can be
both particle and wave at the same time. But universe-centred thinking has
shown that this assumption can be wrong outside the human domain. 

The human-centred view is as old as humanity itself. It seems to be the
default pattern of thinking for most of us, and that makes sound
evolutionary sense. The universe-centred view appeared more recently. In the
sense that we're thinking of - science and the scientific method -
universe-centred thinking has become widespread only in the last three or
four hundred years. It is still a minority view, but a very influential one.
To see why, we must understand two things: how science goes about its
business, and what constitutes scientific evidence. 


For those of us who are willing to pay attention, the universe-centred view
has revealed just how big, how ancient, and how awe-inspiring the universe
is. Even on a human scale, it's a very impressive place, but our parochial
perceptions pale into insignificance when confronted by the mind-numbing
reality. 

When early humans roamed the plains of Africa, the world must have seemed
huge, but it was actually extremely small. A big distance was what you could
walk in a month. An individual's experience of the world was limited to the
immediate region in which he or she lived. For most purposes, a
human-centred view works very well for such a small world. The important
plants and animals - the ones useful to specific groups of humans - were
relatively few in number, and located in their immediate vicinity. One
person could encompass them all, learn their names, know how to milk a goat
or to make a roof from palm fronds. The deeper message of the Egyptian
hieroglyphs is not how diverse that culture's flora and fauna were, but how
narrowly its symbolism was tailored to the organisms that were important to
everyday Egyptian life. 

As we came to understand our world more deeply, and asked new questions,
comfortable answers in terms that we could intuitively understand began to
make less and less sense. Conceivably the Sun might, metaphorically, be
pushed around by an invisible giant dung-beetle, but the Sun is a vast ball
of very hot gas and no ordinary beetle could survive the heat. You either
fix things up by attributing supernatural powers to your beetle, or you
accept that a beetle can't hack it. You then have to accept that the motion
of the Sun occurs for reasons that differ significantly from the purposeful
shoving of a beetle storing up food for its larvae, raising the interesting
question 'why or how does it move??. Similarly, although the setting Sun
looks as if it is disappearing underground, you can come to understand that
it is being obscured by the rotating bulk of the Earth. Instead of telling a
story that offers little real insight, you've learned something new about
the world. 

It took time for humanity to realise all this, because our planet is far
larger than a village. If you walked 40 kilometres every day it would take
you three years to travel all the way round the world, ignoring ocean
crossings and other obstacles. The Moon is nearly ten times as far away; the
Sun is 390 times as far away as the Moon. To get to the nearest star, you
must multiply that figure by a further 270,000. The diameter of our home
galaxy is 25,000 times as great again. The nearest galaxy of comparable
size, the Andromeda galaxy, is 25 times as far away. The distance from Earth
to the edge of the observable visible universe is more than 18,000 times as
great as that. In round figures, 400,000,000,000,000,000,000,000 kilometres.


Four hundred sextillion. That's some village. 

We have no intuitive feel for anything that large. In fact, we have little
intuitive feel for distances of more than a few thousand miles, and those
only because many of us now travel such distances by air - which shrinks the
world to a size we can comprehend. From London, New York is just a meal
away. 


We know that the universe is that big, and that old, because we have
developed a technique that consciously and deliberately sets aside the
human-centred view of the world. It does so by searching not just for
evidence to confirm our ideas, which human beings have done since the dawn
of time, but for evidence that could disprove them, a new and rather
disturbing thought. This technique is called science. It replaces blind
faith by carefully targeted doubt. It has existed in its current form for no
more than a few centuries, although precursors go back a few thousand years.
There is a sense in which 'know' is too strong a word, for scientists
consider all knowledge to be provisional. But what we 'know' through science
rests on much more secure foundations than anything else that we claim to
know, because those foundations have survived being tested to destruction. 

Through science, we know how big and how old the Earth is. We how big and
how old our solar system is. We know how big and how old the observable part
of the universe is. We know that the temperature at the centre of the Sun is
about 15 million degrees Celsius. We know that the Earth has a roughly
spherical core of molten iron. We know that the Earth is roughly, though not
exactly, spherical, and that (with suitable caveats about moving frames of
reference) our planet goes round the Sun rather than being fixed in space
while the Sun goes round it. We know that many features of an animal's form
are determined, to a significant degree, by a long, complicated molecule
that lives inside the nucleus of its cells. We know that bacteria and
viruses cause most of the world's diseases. We know that everything is made
from seventeen fundamental particles. 

'Know' is one of those simple yet difficult words. How can we know, to take
a typical example, what the temperature is at the Sun's centre? Has anyone
been there to find out? 

Well, hardly. If scientists are right about the temperature at the centre of
the Sun, nobody who was suddenly transported there would survive for a
nanosecond. In fact, they'd burn up long before they even reached the Sun.
We haven't sent measuring instruments to the centre of the Sun, for the same
reason. So how can we possibly know how hot it is at the centre, when no
person or instrument can be sent there to find out? 

We know such things because science is not limited to just observing the
world. If it were, it would be firmly back in the human-centred realm. Its
power derives from the possibility of thinking about the world, as well as
experiencing it. The main tool of science is logical inference: deducing
features of the world from a combination of observation, experiment and
theory. Mathematics has long played a key role here, being the best tool we
currently have for making quantitative inferences. 

Most of us understand in broad terms what an observation is: you take a look
at things, you measure some numbers. Theories are trickier. Confusingly, the
word 'theory' has two distinct meanings. One is 'an idea about the world
that has been proposed, but has not yet been tested sufficiently for us to
have much confidence that it is valid'. A lot of science consists of
proposing theories in this sense, and then testing them over and over again
in as many ways as possible. The other meaning is 'an extensive,
interconnected body of ideas that have survived countless independent
attempts at disproof'. These are the theories that inform the scientific
worldview. Anyone who tries to convince you that evolution is 'only a
theory' is confusing the second use with the first, either through intention
to mislead, or ignorance. 

There is a fancy word for the first meaning: 'hypothesis'. Few people
actually use this because it always sounds pedantic, although 'hypothetical'
is familiar enough. The closest ordinary word to the second meaning is
'fact', but this has an air of finality that is at odds with how science
works. In science, facts are always provisional. However, well-established
facts - well-developed and well-supported theories - are not very
provisional. It takes a lot of evidence to change them, and often a change
is only a slight modification. 

Occasionally, however, there may be a genuine revolution, such as relativity
or quantum theory. Even then, the previous theories often survive in a
suitable domain, where they remain accurate and effective. NASA mostly uses
Newton's dynamics and his theory of gravity to compute the trajectories of
spacecraft, not Einstein's. An exception is the GPS system of navigational
satellites, which has to take relativistic dynamics into account to compute
accurate positions. 

Science is almost unique among human ways of thinking in not only permitting
this kind of revisionism, but actively encouraging it. Science is
consciously and deliberately universe-centred. That is what the 'scientific
method' is about. It is like that because the pioneers of science understood
the tricks that the human mind uses to convince itself that what it wants to
be true is true - and took steps to combat them, rather than promoting them
or exploiting them. 

There is a common misconception of the scientific method, in which it is
argued that there is no such thing because specific scientists stuck to
their guns despite apparent contrary evidence. So science is just another
belief system, right? 

Not entirely. The mistake is to focus on the conservatism and arrogance of
individuals, who often fail to conform to the scientific ideal. When they
turn out to have been right all along, we hail them as maverick geniuses;
when they don't, we forget their views and move on. And that's how the real
scientific method works. All the other scientists keep the individuals in
check. 

The beauty of this set-up is that it would work even if no individual
operated according to the ideal model of dispassionate science. Each
scientist could have personal biases - indeed, it seems likely that they do
- and the scientific process would still follow a universe-centred
trajectory. When a scientist proposes a new theory, a new idea, other
scientists seldom rush to congratulate him or her for such a wonderful
thought. Instead, they try very hard to shoot it down. Usually, the
scientist proposing the idea has already done the same thing. It's much
better to catch the flaw yourself, before publication, than to risk public
humiliation when someone else notices it. 

In short, you can be objective about what everyone else is doing, even if
you are subjective about your own work. So it is not the actions of
particular individuals that produce something close to the textbook
scientific method. It is the overall activity of the whole community of
scientists, where the emphasis is on spotting mistakes and trying to find
something better. It takes only one bright scientist to notice a mistaken
assumption. A PhD student can prove a Nobel prize-winner wrong. 

If at some future date new observations conflict with what we think we know
today, scientists will - after considerable soul-searching, some stubborn
conservatism, and a lot of heated argument - revise their theories to
resolve the difficulties. This does not imply that they are merely making
everything up as they go along: each successive refinement has to fit more
and more observations. The absence of complete certainty may seem a
weakness, but it is why science has been so successful. The truth of a
statement about the universe does not depend on how strongly you believe it.

==Endsnip<<


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