Proof, whether in
science, philosophy, the criminal
courts or daily life, is an elastic
concept, interestingly beset with
all kinds of human weakness, as
well as ingenuity. When jealous
Othello demands proof that his
young wife is deceiving him, (when
of course, she is pure) it is not
difficult for Iago to give his
master exactly what he masochistically
craves. For centuries, brilliant
Christian scholars demonstrated
by rational argument the existence
of a sky-god, even while they knew
they could permit themselves no
other conclusion. The mother wrongly
jailed for the murder of her children,
on the expert evidence of a paediatrician,
reasonably questions the faith
of the courts in scientific proof
concerning sudden infant death
syndrome. When Penelope is uncertain
whether the shaggy stranger who
turns up in Ithaca really is her
husband Ulysses, she devises a
proof invoking the construction
of their nuptial bed which would
satisfy most of us, but not many
logicians. The precocious 10-year-old
mathematician who exults in the
proof that the angles of a triangle
always add up to 180° will
discover before his first shave
that in other mathematical schemes
this is not always so. Very few
of us know how to demonstrate that
two plus two equals four in all
circumstances. But we hold it to
be true, unless we are unlucky
enough to live under a political
dispensation that requires us to
believe the impossible; George
Orwell in fiction, as well as Stalin,
Mao, Pol Pot and various others
in fact, have shown us how the
answer can be five.
It has been surprisingly
difficult to establish definitively
what the truth is about any matter,
however simple. It is always hard
to get a grasp of one's own innate
assumptions, and it was once perilous
to challenge the wisdom of the
elders, or the traditions that
have survived the centuries, and
dangerous to incur the anger of
the gods, or at least, of their
earthly representatives. Perhaps
it was the greatest invention of
all, greater than that of the wheel
or agriculture, this slow elaboration
of a thought system, science, that
has disproof at its heart
and self-correction as its essential
procedure. Only recently, over
this past half-millennium, has
some significant part of humankind
begun to dispense with the kinds
of insights supposedly revealed
by supernatural entities, and to
support instead a vast and disparate
mental enterprise that works by
accretion, dispute, refinement
and occasional radical challenges.
There are no sacred texts—in
fact, a form of blasphemy has turned
out to be useful. Empirical observation
and proof are, of course, vitally
important, but some science is
little more than accurate description
and classification; some ideas
take hold, not because they are
proved, but because they are consonant
with what is known already across
different fields of study, or because
they turn out to predict or retrodict
phenomena efficiently, or because
persuasive persons with powers
of patronage hold them—naturally,
human frailty is well represented
in science. But the ambition of
juniors and an adversarial method,
as well as mortality itself are
mighty forces. As one commentator
has noted, science proceeds by
funerals.
And again, some science
appears true because it is elegant—it
is economically formulated, while
seeming to explain a great deal.
Despite fulmination against it
from the pulpit, Darwin's theory
of natural selection gained rapid
acceptance, at least by the standards
of Victorian
intellectual life. His proof
was really an overwhelming set
of examples, laid out with exacting
care. A relatively simple idea
made sense across a huge variety
of cases and circumstances, a fact
not lost on an army of Anglican
vicars in country livings, who
devoted their copious free time
to natural history. Einstein's
novel description, in his theory
of general relativity, of gravitation
as a consequence, not of the attraction
between bodies according to their
mass, but of the curvature of space-time
generated by matter and energy,
was enshrined in textbooks within
a few years of its formulation.
Steven Weinberg describes how,
from 1919 onwards, various expeditions
by astronomers set out to test
the theory by measuring the deflection
of starlight by the sun during
an eclipse. Not until the availability
of radio telescopy in the early
50s were the measurements accurate
enough to provide verification.
For 40 years, despite a paucity
of evidence, the theory was generally
accepted because, in Weinberg's
phrase, it was "compellingly
beautiful."
Much has been written
about the imagination in science,
of wild hunches born out, of sudden
intuitive connections, and benign
promptings from mundane events
(let no one forget the structure
of benzene and of Kekule's dream
of a snake eating its tail) and
of the occasional triumph of beauty
over truth. In James Watson's account,
when Rosalind Franklin stood before
the final model of the DNA molecule,
she "accepted the fact that
the structure was too pretty not
to be true." Nevertheless,
the idea still holds firm among
us laypeople that scientists do
not believe what they cannot prove.
At the very least, we demand of
them higher standards of evidence
than we expect from literary critics,
journalists or priests. It is for
this reason that the 2005 Edge
question—what do you believe
that you cannot prove?—has
generated so much public interest,
for there appears to be a paradox
here: those who stake their intellectual
credibility on rigorous proof are
lining up to declare their various
unfalsifiable beliefs. Should not
skepticism be the kissing cousin
of science? Those very men and
women who castigated us for our
insistence on some cloudy notion
that was not subject to the holy
Trinity of blind, controlled and
randomised testing, are at last
bending the knee to declare their
faith.
The paradox, however,
is false. As the Nobel laureate
Leon Lederman writes in his reply:
"to believe something while
knowing it cannot be proved (yet)
is the essence of physics."
This collection, mostly written
by working scientists, does not
represent the antithesis of science.
These are not simply the unbuttoned
musings of professionals on their
day off. The contributions, ranging
across many disparate fields, expressed
the spirit of a scientific consciousness
at its best—informed guesswork
that is open-minded, free ranging,
intellectually playful. Many replies
offer versions of the future in
various fields of study. Those
readers educated in the humanities,
accustomed to the pessimism that
is generally supposed to be the
mark of a true intellectual, will
be struck by the optimistic tone
of these pages. Some, like the
psychologist Martin Seligman, believe
we are not rotten to the core.
Others even seem to think that
the human lot could improve. Generally
evident in these pages is an unadorned
pleasure in curiosity. Is there
life, or intelligent life, beyond
the earth? Does time really exist?
Is language a precondition of consciousness?
Are cockroaches conscious? Is there
a theory beyond quantum mechanics?
Or indeed, do we gain a selective
advantage from believing things
we cannot prove? The reader will
find here a collective expression
of wonder at the living and inanimate
world which does not have an obvious
equivalent in, say, cultural studies.
In the arts, perhaps lyric poetry
would be a kind of happy parallel.
Another interesting
feature is the prevalence here
of what E. O. Wilson calls "consilience."
The boundaries between different
specialised subjects begin to break
down when scientists find they
need to draw on insights or procedures
in fields of study adjacent or
useful to their own. The old Enlightenment
dream of a unified body of knowledge
comes a little closer when biologists
and economists draw on each other's
concepts; neuroscientists need
mathematicians, molecular biologists
strayed into the poorly defended
territories of chemists and physicists.
Even cosmologists have drawn on
evolutionary theory. And everyone,
of course, needs sophisticated
computing. To address each other
across their disciplines, scientists
have had to abandon their specialised
vocabularies and adopt a lingua
franca—common English.
The accidental beneficiary, of
course, has been the common reader,
who needs no acquaintance with
arcane jargon to follow the exchanges.
One consequence—and perhaps
symbol—of this emerging synthesis
has been the Edge
website and its peculiarly heady
intellectual culture. These pages
represent only a small part of
an ongoing and thrilling colloquium
that is open to all.
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