In 1837, Charles Darwin presented a paper to
the British Geological Society arguing that coral atolls were formed not on
submerged volcanic craters, as argued by pioneering geologist Charles Lyell,
but on the subsidence of mountain chains. The problem, as Darwin saw it, was
that corals can not live more than about 30 feet below the surface and
therefore they could not have formed of themselves from the ocean floor. They
needed a raised platform to build upon.
However, the volcanic crater hypothesis
didn’t satisfy Darwin; he thought the atoll shape was too regular to have been
the craters of old volcanos. There were no atoll formations on land, Darwin
reasoned; why would there be such in the ocean? Therefore, Darwin proposed that
corals were building upon eroded mountains, an hypothesis that, he wrote
happily, “solves
every difficulty.” Darwin also argued, in 1839, that curious geological
formations—what appeared to be parallel tracks—in the Glen Roy valley of
Scotland were the result of an uplifted sea bed.
Darwin didn’t have any actual physical
evidence to support these two hypotheses: he arrived at them deductively,
through the principle of exclusion. A deductive conclusion is reached through
theory—if X, then logically Y must be so—as opposed to induction, which builds
a theory out of empirical data. The principle of exclusion works from the
premise that “there
is no other way of accounting for the phenomenon.”[1]
As it turned out, Darwin was wrong on both hypotheses.
Later physical evidence showed that Lyell’s volcano theory was closer to the
mark, and the Glen Roy tracks were caused by glaciers, which were still a
mystery in Darwin’s time.
Darwin later wrote of his Glen Roy
hypothesis: “Because
no other explanation was possible under our then state of knowledge, I argued
in favour of sea-action; and my error has been a good lesson to me never to
trust in science to the principle of exclusion.”[2]
While Darwin rejected the principle of
exclusion, at least as a primary scientific tool, alarmist climate science has
not. Instead, the principle of exclusion is one of the most-cited arguments to
support the anthropogenic global warming (AGW) hypothesis.
For example, in a 2010 interview with the BBC
on the Climategate scandal, Climate Research Unit (CRU) head Phil Jones was
asked:
“What
factors convince you that recent warming has been largely man-made?” Jones’s
reply: “The
fact that we can’t explain the warming from the 1950s by solar and volcanic
forcing.”
In other words, Jones is using the principle of exclusion:
while he and his colleagues can’t prove that human activities are causing
warming, they can’t find any other explanation.
Canada’s Andrew Weaver also relies on the
principle of exclusion when he writes, in his 2008 book Keeping Our Cool:
“There is no known
natural climate mechanism to explain the warming over the 20th century. And
that is one of the many pieces suggesting that a substantial portion of the
warming of the 20th century is associated with greenhouse gases.”[3]
Similarly, the IPCC’s 2007 report notes:
“Most of the
observed increase in globally averaged temperatures since the mid-20th century
is very likely due to the observed increase in anthropogenic greenhouse gas
concentrations.”
The IPCC has no empirical proof that human carbon
emissions are the main cause of planetary warming; the “proof” is that the
scientists can’t find another explanation, i.e., the principle of exclusion.
It’s not unreasonable to claim that human
activities are the main cause of global warming. If carbon emissions and
temperatures increase at the same time, it’s possible they are connected
although, of course, correlation does not equal causation. And many scientific
theories are based on the principle of exclusion, including much of Darwin’s
theory of evolution itself.
Where alarmists like Jones, Weaver and the
IPCC betray the accepted principles of science is in claiming that a possible
causal connection between human carbon emissions and temperatures is settled,
certain, and, as Weaver puts it in his book, beyond debate (he writes: “there
is no such debate [about the certainty of the AGW hypothesis] in the
atmospheric or climate scientific community” (p. 22)).
Even worse, these scientists call anyone who
dares to challenge their hypothesis a “denier,” deluded, a fraud, bought-off by
the oil industry, or worse. One cannot imagine Darwin, a modest scientist,
making similar claims of certainty for his two hypotheses, or throwing slurs at
anyone who didn’t accept them.
Yet there may well be other explanations for
a warming earth that we still don’t know about or enough about—the cosmic ray
theory seems like a good contender, as do fluctuations in solar intensity and
cyclical ocean temperatures: given the complexity of climate, there are many
possible causes for a temperature rise (or fall).
But, then,
the deductive rather than empirical (inductive) nature of alarmist climate
science was stated clearly by climatologist Chris Folland two decades ago:
“The data don’t
matter… We’re not basing our recommendations on the data. We’re basing them on
the climate models.”[4]
And so, alarmist climate scientists find
themselves under siege by skeptics and increasingly distrusted by the public
because they blindly accept the principle of exclusion, in the face of
considerable empirical facts that don’t fit the AGW hypothesis. For example,
for more than a decade, the earth has not warmed as the AGW hypothesis
predicts. Nor are the oceans warming as the hypothesis predicts. Yet, when
skeptics point out the problems, alarmists cannot admit they have made a
mistake because then the whole alarmist edifice (and the juicy research grants
that go with it) would collapse.
Darwin himself battled the principle of
exclusion in proposing the theory of natural selection. Up to Darwin’s time, no
one could think of any other way to explain the creation of species than by an
all-powerful god. This led scientists and clerics into all sorts of logical
absurdities, such as claims that the earth was mere thousands of years old or
that God had put fossils into the earth to test scientists’ faith. However, in
the mid-1800s, there was no better explanation to hand.
Darwin (and Alfred Russell Wallace) supplied
a better, more scientific explanation: nature itself, acting over eons of time,
was the creator of species, an hypothesis so simple and so logical that Thomas
Huxley, Darwin’s main promoter, declared: “How extremely stupid not to have thought of
that.”
The AGW hypothesis may well prove to be
correct. However, the simplest and most logical explanation for climate change,
in the past, now, and in the future, is natural variation. If so, then the AGW
hypothesis, based on the treacherous principle of exclusion, will go the way of
Darwin’s two hypotheses on the Glen Roy tracks and the creation of coral
atolls.
And so, while alarmist climate scientists are
quite within their rights to propose the AGW hypothesis, they should also be
cautious: AGW is an hypothesis. It has not reached the status of a scientific
theory (it has not passed enough scientific tests for that), nor is it a
scientific fact, as the public is told. Instead, alarmist climate scientists
have thrown the proper scientific caution to the winds to make claims that
aren’t supported by the evidence, and to smear those who point out the possible
errors in their hypothesis.
To repeat Darwin’s words:
“My error has been
a good lesson to me never to trust in science to the principle
of exclusion"
This
caution is especially true when climate-science errors could lead to
anti-carbon policies that will cost billions of dollars and destroy millions of
livelihoods, while having no effect upon the climate because humans are only a
small part of a much larger picture.
Darwin gave good advice: beware the principle
of exclusion. It’s a pity that today’s alarmist climate scientists are
unwilling to heed that advice.
[1] Darwin’s
thought process is described in Gertrude Himmelfarb, Darwin and the Darwinian
Revolution. New York: W.W. Norton, 1962 (1959), pp. 99-106.
[2] Charles Darwin, Life and Letters, I, London, 1887, p. 69. Quoted in
Himmelfarb, p. 106.
[3] Andrew Weaver, Keeping Our Cool: Canada in a Warming World. Toronto:
Viking, 2008, p. 59.
[4] Quoted in Patrick J. Michaels, Sound and Fury: The Science and Politics of
Global Warming. Washington: Cato Institute, 1992, p. 83.
Paul MacRae is the
author of False Alarm: Global Warming—Facts Versus Fears, and publishes the
blog False Alarm at paulmacrae.com
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