快猫短视频

DOES science tell us the truth? How do we tell the difference between science
and non-science? If one group of scientists says that genetically modified foods
are harmless and another says they are dangerous, who should we believe? To
answer these questions we must think about the way scientists reach their
conclusions.

Science鈥檚 goal is to discover the laws of nature, which we assume exist
independently of humans. We find these laws by collecting facts and assembling
new theories to explain them. Good science is conducted publicly. 快猫短视频s
release their results in a way that allows others to scrutinise them and try to
duplicate them or show that they are wrong. Few people seriously doubt that
science works. It has been hugely successful in giving us explanations of the
world around us. It has the power ultimately to explain all natural phenomena,
even if in practice some problems are proving very difficult. Science has also
allowed us to create technologies such as drugs to treat cancer or the laser in
your CD or MiniDisc player.

WHAT IS SCIENCE?

Testing ideas

No one has yet defined what science is in a way that satisfies everyone.
Science, for example, cannot give absolute proofs of the laws of nature because,
although we can test an idea repeatedly, we can never be sure that an exception
does not exist. Some religious fundamentalists and TV psychics exploit this
difficulty, and claim that science is just another set of beliefs, with no more
validity than any other. But while science may not give us absolute truth, this
doesn鈥檛 mean we must give equal time to magicians and the like. Far from it.

To see why, we need to examine the philosophy of science. Like other
branches of philosophy this involves thinking about thinking (the word
originally meant 鈥渓ove of wisdom鈥�). The philosophy of science uses similar
methods to a mathematical proof: a step-by-step examination of
assumptions, data and conclusions.

A classic philosophical question is: 鈥淒o I exist? How do I know that I am not
just a program in some immense supercomputer that is feeding me false sensations
about a simulated world?鈥� The French mathematician and philosopher Ren茅
Descartes (1596-1650) answered this question with a proof involving the famous
statement, 鈥淚 think, therefore I am.鈥� In other words, the act of doubting that
we exist proves we exist; there must be something that thinks about the problem
of proving existence.

The philosophy of science examines scientific method and asks what it
can tell us. Science deals with empirical knowledge. This is knowledge about the
Universe that we acquire by examining how it appears to our
senses鈥攅nhanced, if necessary, by instruments such as microscopes or
particle accelerators鈥攔ather than by sitting and thinking. Empiricism
sounds like common sense, but as a way of learning about the world it is
comparatively recent. It triumphed in the scientific revolution of the 16th and
17th centuries, when Galileo Galilei, Robert Boyle, Isaac Newton and others
showed that facts gained from empirical observations could revolutionise our
picture of the world.

This was where science parted company with magic. Although there was some
overlap at the time鈥擭ewton was an enthusiastic alchemist, and mystical
texts may have inspired him to think of gravity鈥攖here is a basic
difference between science and magic. Science involves repeatable observations
and open publication. There are no hidden or 鈥渙ccult鈥� texts, and when an
experiment does not work we do not blame the heavens, the experimenter鈥檚 lack of
spiritual purity or鈥攁 favourite of today鈥檚 TV magicians鈥斺�漛ad vibes鈥�
from critical observers.

Empiricism creates its own philosophical problems, however. How do facts lead
to theories and laws of nature? Imagine an experiment involving observations of
apples. After watching apples fall from trees, and verifying that apples will
also fall if dropped from the hand, or from the top of a tall building or other
tall structures, we reason that a fundamental law is responsible. We call it
gravity, and we predict that when we release an apple or any similar object in
midair, it will fall to the ground.

When we make a prediction based on past experience, we are moving from
statements based on our observations, such as 鈥渢he apple fell to the ground鈥�, to
universal statements such as 鈥渁ll apples in the future will fall to the ground鈥�.
This leap from the singular to the universal is called inductive
reasoning.

Inductive reasoning appeals to common sense, but is logically flawed. The
empiricist philosopher David Hume (1711-76) pointed out that there can be no
logical connection across time. Just because something has happened many times
in the past does not prove that it will happen in the future. Karl Popper
(1902-94) pointed out that scientific verification doesn鈥檛 actually prove
anything. No matter how many times we record in our notebooks the fact of
observing a white swan, we get no closer to proving the universal statement that
all swans are white. Popper decided that science finds facts not by verifying
statements but by falsifying them. We may never be able to prove that all
swans are white, but the first time we see a black swan we can firmly disprove
it.

To reason in this way runs counter to intuition
(see Figure 1). Logically,
however, it is very powerful, and scientists make good use of this power. Popper
said that science progresses by testing hypotheses. One scientist holds up a
hypothesis for examination鈥� for example, that gravity bends light waves.
Colleagues or rivals then subject this hypothesis to experimental tests that
could show it to be false. If the hypothesis survives repeated tests, it becomes
accepted as scientific truth.

笔辞辫辫别谤鈥檚 ideas provide a link between theory and experiment. They tell us
that no matter how many tests a hypothesis survives, we will never have a
philosophical proof that it is true. Popper wrote: 鈥淭here can be no ultimate
statements in science . . . and therefore none which cannot in principle be
refuted.鈥� This makes a willingness to accept falsification central to science.
快猫短视频s must behave rationally and gracefully, by stating in advance what
experimental observations would disprove their hypothesis, and if such findings
do emerge, accepting that their hypothesis was wrong.

This was important to Popper, who was born in Austria and whose life was
dominated by struggles against ideologies such as those of Nazi Germany, which
tolerated no doubts. Popper also contrasted Albert Einstein鈥檚 theories of
relativity with Karl Marx鈥檚 theories of history. While Einstein offered his
followers tests, such as solar eclipses, which might have disproved his
theories, Marxists were undeterred when history did not unfold according to
prediction. Popper also attacked Freudian psychology and Darwinian evolution for
what he saw as their unfalsifiability.

Most working scientists today would go along with the idea of falsification.
But 笔辞辫辫别谤鈥檚 ideas leave us with several problems:

鈥� Falsification alone cannot distinguish science from non-science. The
hypothesis that reindeer can fly is falsifiable by any scientist with access to
a herd of reindeer, a high cliff and an unusually compliant ethics committee. No
one, however, would describe the hypothesis as scientific.

鈥� Where do hypotheses come from? One answer might be that they are merely the
application of general principles. For example, they might be inspired by the
principle鈥攏amed after the medieval philosopher William of
Occam鈥攌nown as Occam鈥檚 razor: the simplest explanations are the
best鈥攐r that the Universe everywhere obeys the same laws of physics. But
this brings us back to the problem of induction.

鈥� Science doesn鈥檛 progress through falsification. In a strictly Popperian
system, we would have to abandon the laws of chemistry every time a school
student got the wrong result in a chemistry practical. Clearly, we do not do
this. We blame the student鈥檚 error, or if confronted with a run of anomalous
findings, contaminated samples or faulty instruments. Sometimes this is wrong.
快猫短视频s rejected early evidence of a hole in the ozone layer over Antarctica
because, rather than accepting such unexpected results, they assumed that the
satellite collecting the data was faulty. This leads us to the next problem.

鈥� How to explain scientific revolutions, discoveries which transform
understanding? Leaps of genius like the theory of evolution by natural
selection, or the theory of relativity, appear to be neither new bricks in the
wall of knowledge nor the consequence of falsifying previous theories.

WAYS OF SEEING

Paradigm shifts

The last question was tackled by Thomas Kuhn (1922-96). In his book The
Structure of Scientific Revolutions, published in 1962, Kuhn said that
scientific revolutions need creative thinking of a kind that cannot grow out of
the old order. He dismissed 笔辞辫辫别谤鈥檚 picture. 鈥淣o process yet disclosed by the
historical study of scientific development at all resembles the methodological
stereotype of falsification by direct comparison with nature,鈥� he said.

Kuhn suggested that science does not develop by the orderly accumulation of
facts and theories, but by dramatic revolutions which he called paradigm
shifts. The worlds before and after a paradigm shift are utterly
different鈥擪uhn鈥檚 term was 鈥渋ncommensurable鈥濃�� and experiments done
under the old order may be worthless under the new.

The switch between before and after is as dramatic as that which occurs when
looking at a trick gestalt-switch picture
(Figure 2). You cannot reject
one view without replacing it with the other. Such switches are rare. Kuhn鈥檚
examples include the Copernican revolution, which adopted the idea that the
Earth orbited the Sun and not the other way round, the discovery of oxygen, and
Einstein鈥檚 theories of relativity. By contrast, most 鈥渘ormal鈥� research takes
place within paradigms. 快猫短视频s accumulate data and solve problems in what
Kuhn called 鈥渕opping-up operations鈥�.

Inevitably, some research throws up findings that do not fit the
paradigm鈥攑erhaps an unexpected wobble in a planet鈥檚 orbit around the Sun.
In 笔辞辫辫别谤鈥檚 model these would immediately falsify the paradigm鈥檚 central
theory. But according to Kuhn, scientists prefer to cling to old paradigms until
a new one is ready. The anomaly is either discarded or, preferably, worked into
the existing paradigm. In this way the elegant model of an Earth-centred
Universe developed in the second century BC by the Greek astronomer Ptolemy
accumulated more and more subsidiary orbits to account for astronomers鈥�
subsequent observations.

After a while, however, the anomalies build up into a crisis of confidence,
and science stalls. Eventually a genius comes up with a new paradigm. Copernicus
realised that the observed orbits of planets made sense when he placed the Sun,
rather than the Earth, in the centre of the Solar System. Kuhn said that such
leaps happen only in times of crisis.

In times of paradigm shift, hard scientific facts can become meaningless, or
change their meaning entirely. For years, scientists made measurements on a
substance called phlogiston, which they thought was given off when objects
burnt. The discovery of oxygen rendered phlogiston meaningless. But chemists
could not discover oxygen until they decided to treat it as a distinct gas. In
other words, oxygen had to be invented as well as discovered
(Figure 3).

Individual scientists are loath to make such leaps, Kuhn says. The revolution
occurs only when practitioners under the old paradigm either die or retire. It
takes a new generation to carry the torch of the new paradigm.

Many people have criticised Kuhn. They say his use of the word 鈥減aradigm鈥� is
imprecise. He chooses his examples overwhelmingly from physics, and they say
other sciences may change in different ways. And scientists do not seem as
reluctant to make paradigm shifts as Kuhn implies. The discovery of DNA鈥檚
double-helix structure utterly changed the way we think about biology, yet
biologists accepted it with enthusiasm, replacing a model based on metabolism
with one based on information. Did this make it less than a paradigm shift?

Likewise the discovery in the late 1980s of new materials that become
superconductors at relatively high temperatures was eagerly pursued by
scientists. Such breakthroughs must throw into doubt Kuhn鈥檚 distinction between
鈥渘ormal鈥� science鈥攖he mopping-up of facts鈥攁nd revolutionary
science.

Finally, Kuhn does not tell us where revolutionary ideas come from. We enjoy
the folklore of scientific breakthroughs happening by accident, as with
Alexander Fleming and penicillin, or through the work of outsiders such as
Einstein. Sadly for Hollywood, such stories are often myths. Although Einstein
was working as a patent office clerk when he came up with his theories of
relativity, he had steeped himself in contemporary work on physics. Fleming
spotted penicillin鈥檚 effects because he was an expert in bacteriology, working
in a laboratory. In science, chance favours the prepared mind.

Most worrying, if Kuhn is right, science is just a matter of fashions and a
kind of crowd psychology, with nothing to distinguish it from pseudoscience.
This problem concerned the Hungarian Imre Lakatos (1922-74), who refined some of
Popper and Kuhn鈥檚 ideas in a way that makes such a demarcation clear. Instead of
鈥渘ormal鈥� and 鈥渞evolutionary鈥� science, Lakatos drew a distinction between
progressive and degenerative research programmes. A progressive
research programme is one that leads to the discovery of facts that were
previously unknown. An example is Newton鈥檚 theory of gravity, which allowed
Halley to predict the return of the comet that now bears his name. A
degenerating research programme allows no such predictions; rather, it must
itself be modified to cope with inconvenient facts. Lakatos cites Marxism, which
although it describes itself as a science has a poor record of predicting a
crucial phenomenon鈥攑olitical revolutions.

In progressive research programmes the appearance of awkward facts, such as
unaccountable wobbles in a planet鈥檚 orbit, is not necessarily fatal to the core
hypothesis. 快猫短视频s can ignore them if the central hypothesis is still coming
up with 鈥渦nexpected, stunning, predictions鈥�, Lakatos says. Revolutions happen
gradually as progressive research programmes replace degenerating ones. But even
in progressive research, facts come after theories.

Theories are clearly made up by humans: they are socially constructed
in modern jargon. Does this mean that scientific facts are too? The idea that
science is a social construct intrigues many people, especially those thinkers
described as 鈥減ostmodernists鈥�. If, according to Popper, scientific laws are
impossible to verify logically and, according to Kuhn, the same findings can
mean different things before and after a scientific revolution, how can science
claim to be any more objective than any other cultural pursuit?

No one would deny that culture, values and beliefs shape our choice of what
science to do. Drugs companies began researching AIDS when it affected people
who could afford to buy medicines rather than rural Africans. Military spending
on research and development is responsible for similar biases. 快猫短视频s
believe, however, that the basic facts of the Universe are there to be
discovered, whatever the motivation for doing so. We spent billions of pounds
developing nuclear weapons, and in the process learned a lot about some strange
metal alloys. But we would have found the same facts in a race to build the
ultimate ploughshare.

The 鈥渟cience wars鈥� being fought out between academics, especially in North
America, question whether this assumption is generally true. Philosophers such
as Bruno Latour in Paris study science as a social phenomenon, and suggest its
results are little more than social rituals.

Some scientists are horrified by the spectre of relativism, which
holds that ideas are not universal or absolute but differ from culture to
culture, individual to individual. A relativist would assert that science is
only one way of discovering the nature of the physical world. The anarchist
philosopher Paul Feyerabend (1924-94), perhaps mischievously, took the
relativist argument to its logical conclusion: 鈥淭here is no idea, however
ancient and absurd, that is not capable of improving our knowledge.鈥� In
Against Method (1975) he defended the Church鈥檚 indictment of Galileo. It
was rational, he said, because there was at the time no reason to suppose that
Galileo鈥檚 crude telescopes could show the mountains on the Moon that he claimed
to have seen. The Church believed that the Moon was a perfect smooth sphere
quite unlike Earth.

TRUST AND TRUTH

Science and non-science

One vigorous defender of science鈥檚 special place is the biologist and author
Richard Dawkins. He notes that when relativist philosophers fly to an
international conference on postmodernism, they generally put their trust in a
high-technology airliner rather than a magic carpet. And, of course, absolute
relativism contains its own contradiction. 鈥淭hose who tell you there is no
absolute truth are asking you not to believe them,鈥� says the contemporary
philosopher Roger Scruton. 鈥淪o don鈥檛.鈥�

One battle in the 鈥渟cience wars鈥� is over Darwin鈥檚 theory of evolution
(see 鈥淓volution under attack鈥�).
Some assaults on evolution come from a particularly stormy debate over
evolutionary psychology or, as it is sometimes called, sociobiology. This
attempts to explain people鈥檚 patterns of behaviour鈥攚hether it be fear of
snakes, or why we enjoy particular kinds of landscape gardening鈥攕olely in
terms of evolutionary advantage.

Evolutionary psychology is controversial because it can be used to justify
types of behaviour, such as violence, which are generally considered
unacceptable. It is possible to challenge the science of evolutionary psychology
without challenging evolution itself.

The phenomenon of consciousness is another problem area. Philosophers
and scientists both stake a claim to holding the key to understanding
consciousness. The fact that some computer scientists believe they can create
artificial consciousness gives the debate extra spice. But any such project will
first have to define what constitutes consciousness, which is probably a job for
philosophy. Science and technology can then take over.

Finally, there is the question of exactly what science is. As we have seen,
笔辞辫辫别谤鈥檚 falsification criterion alone is not enough to distinguish
science from non-science. In fact, if we look at the whole array of science,
from particle physics to cell biology to ecology to engineering, it is hard to
find any single practice that they all have in common. Even openness is not
always there: much research is kept secret for military or commercial
reasons.

A way out is to use a concept developed by one of the most important
20th-century philosophers, Ludwig Wittgenstein (1889-1951), that of family
resemblance. There are many groups of human activities that are impossible
to define exactly. For example, it鈥檚 hard to say what a game is, but when we see
a new game we have no trouble deciding that that鈥檚 what it is, because of the
things it shares with other members of the games family. Likewise with science:
all we can say about good science is it has most of the qualities of
other activities we call good science, including empiricism, peer review
and openness to refutation.

Those who work in this family believe that truth is out there. Perhaps not
always in the strictest philosophical sense, but enough for practical purposes
and definitely enough to distinguish science from propaganda and muddled
thinking. 快猫短视频s do not need to be shy of admitting that its laws are always
provisional. That is not a weakness, but science鈥檚 greatest strength.

THE philosophy of science figures in heated modern debates, such as the
relationship of science and religion. The idea that science must conflict with
Christian religion is recent. Newton was a devout if unorthodox Christian who
saw science as revealing the wonders of creation, not challenging them. Indeed
what is known as the argument from design鈥攖hat the world is too
intricately created to have arisen by chance鈥� was cited as a scientific
proof that God existed. Darwin鈥檚 work smashed that consensus. Evolution by
natural selection demonstrated that we do not need a divine creator to explain
where human beings came from.

Today Darwinism itself is under fire, although the attacks are rarely overtly
religious. The target is generally the philosophy of Darwinian evolution. Some
critics cite Popper, who said that the theory of evolution by natural selection
is unscientific because it is unfalsifiable. In one sense, this is correct: we
cannot rerun the tape of the past 5 billion years. But thousands of biologists
every day test evolution鈥檚 crucial components and processes. Fame and a large
fortune in the biotechnology business await any scientist who can find a short
cut to the slow grind of Darwinian evolution. No one has.

Of course, Darwinism is 鈥渙nly a theory鈥�, but this does not mean that all
other theories deserve equal respect.