The History and the Pseudo-History of Science
by Gene Callahan

Recently, after looking in an introductory biology textbook for a
description of meiosis, I browsed through its introduction. There, I
came upon the following passage:

"For 2,000 years prior to [the Renaissance], scholars had accepted the
writings of Aristotle and other ancient philosophers, as well as
certain Church doctrines, to be unfaltering truths about the natural
world. It took some of the greatest minds in history, including
Copernicus, Galileo, and Newton, to shake this dominion of dogma and to
replace it with theories and laws based on direct observation of
nature. Nicholaus Copernicus, and later Galileo, made calculations that
the Earth and other planets circle the sun..." (Wessells and Hopson,
1988, p. 11).

Many science textbooks contain similar one-or-two-paragraph histories
of how modern science miraculously emerged from the dark swamp of
ignorance we call the Middle Ages. The main problem with such stories
is that they are almost entirely false. Let's compare the picture
painted above with the current understanding of scholars studying the
history of the Scientific Revolution.

The first assertion, quite a commonplace one, is that from the time of
the ancient Greeks until the Renaissance, the European mind was in the
thrall of a dogmatic worldview, based only on authority, and made no
progress toward a better understanding of the natural world. It is
certainly true that scientific ideas developed much less rapidly during
most of the period in question than they have in recent centuries.
(Even admitting that much, the figure of "2000 years" in the quote
above still seems to overshoot the mark, since it includes the time of
pioneers like Archimedes and Ptolemy within its scope.) During the
"Dark Ages," in the centuries immediately after the fall of Rome,
Western Europe did not challenge the received wisdom in science
primarily because it did not do much science at all. People were
struggling to survive, and intellectual life fell into abeyance. In
fact, contrary to the view expressed in the biology textbook, for most
of that period, Aristotle's writings were lost to the West, so that
they could hardly have been accepted as "unfaltering truths"!

But as Western European intellectual life revived, scholars began
reconsidering the ideas of the ancients. As Bede's Library has it:

"When Aristotle was rediscovered in the West, it was soon established
that when there were clear conflicts between his philosophy and the
Christian faith, the latter should always prevail. This was not much of
a handicap, as on the subject of physical science, faith did not really
have a lot to say. The bible could be read non-literally where
necessary, as Augustine himself allowed, so William of Conches could
even call the creation account in Genesis figurative. Nearly everyone
agreed that the earth was a sphere even though the Bible implied a flat
earth. But where Aristotle and faith were in clear conflict, such as
his claim that the world was uncreated and eternal, it weakened his
authority and allowed his ideas to be challenged. This opened the door
to the idea of a developing body of knowledge, which is often assumed
to have been absent from the medieval outlook."

For example, in the fourteenth century, a group of philosophers, most
of them at the University of Paris, developed the impetus theory of
motion. It was both a break with one of the central ideas of
Aristotle's physics, and a step toward the modern theory of inertia.
They also disputed the prevailing belief that the movement of each
planet was guided by a conscious being:

"Although the theory of celestial intelligences became a central
doctrine in Hellenic, Arabic and scholastic cosmology, it was attacked
during the fourteenth century by several scholars, and most incisively
in the work of Jean Buridan (died c. 1358) and his pupil Nicole Oresme
(1320-1382)."

Nevertheless, Aristotelian physics did remain the primary means of
explaining most physical phenomena well into the Scientific Revolution.
There is a very good reason for that, which brings us to our next
point. The textbook cited above claims that scientists such as
Copernicus, Galileo, and Newton were able "to shake this dominion of
[Aristotelian] dogma" with "theories and laws based on direct
observation of nature." Once again, the authors are repeating a
commonplace view, one that appears in a multitude of popular accounts
of the rise of science. The scholastic philosophers who dominated the
medieval universities, enraptured with their elaborate metaphysical
speculations, ignored the plain facts of the physical world, which were
accessible to them if they had simply looked around. The great figures
of the Scientific Revolution relied instead on observation, which led
them to develop the theories that replaced Aristotelian physics.

But this story, inspiring though it is, runs afoul of the fact that
Aristotle was a masterful observer, one whose physical theories are
closely based on the world as it appears to the unaided senses.
Knowledge, he held, begins with our observations of the world around
us. Similarly, Ptolemy constructed his Earth-centered model of the
cosmos to accurately reflect the best astronomical observations
available to him.

In fact, it was the pioneers of the Scientific Revolution who had to
overcome the commonsense view of the world revealed by direct
observation in order for their theories to gain acceptance. The most
obvious discrepancy between the reports of our senses and the new ideas
is that the Earth seems quite plainly to be standing still, while the
heavenly bodies clearly appear to be rotating around it. Renaissance
man had no experience of, for instance, traveling in an airplane at 600
miles per hour yet feeling as though he wasn't moving. When he moved
rapidly, such as on horseback, he could feel that he was moving. And to
account for the apparent motions of the heavenly bodies, the Earth
would have to rotate at what, for him, was a truly astonishing rate.
(At the equator, the actual speed is over 1000 miles per hour.)

What's more, if the Earth was spinning around that rapidly, it seemed
that we ought to be able to detect that motion in many ways. For
example, if you dropped a rock from a tower, it should fall some
distance from the tower's base, in the direction opposite to the
Earth's rotation, since the ground would have moved under it as it was
falling. The Earth's atmosphere would also be left behind, so that
there would be a continuous wind sweeping from east to west at hundreds
of miles per hour.

On a more technical level, a major reason that Copernicus's
heliocentric (sun-centered) theory was rejected by many leading
astronomers of the sixteenth century was the absence of any observed
parallax in the "fixed stars." Parallax is the astronomical term for
the fact that objects will appear to change their location when
observed from different places. If the Earth revolves around the sun,
the stars should appear to move slightly during the course of the year,
but astronomers observed no such phenomena. (The explanation for that
failure is that the stars are much farther away from the Earth than
anyone at that time suspected, so that the parallax was too minute for
their instruments to detect.)

Copernicus handled the difficulty that presented for his theory with an
ad hoc hypothesis, declaring that the sphere of the stars was ten times
farther from the Earth than had previously been believed. Not only was
the hypothesis ad hoc, it was also, as a Popperian would put it,
unfalsifiable: there were no instruments available at the time to
measure a parallax as small as the new distance implied. And if a
geocentric astronomer had developed a device capable of measuring such
a slight change in observed position, Copernicus could (and undoubtedly
would) have simply moved the stellar sphere ten times farther away
still.

Copernicus also "was puzzled by the variations he had observed in the
brightness of the planet Mars. [But] Copernicus's own system was so
far from answering to the phenomena in the case of Mars that Galileo in
his main work on this subject praises him for clinging to his new
theory though it contradicted observation..." (Butterfield, 1949, p.
23).

What's more, as we noted above, Copernicanism violated many of the
principles of the Aristotelian physics of his time. Copernicus could
not explain why objects didn't fly off the rotating Earth, why the
Earth didn't spin itself apart, why dropped objects fell straight to
the ground, or what kept celestial objects going in their orbits if not
the motion transmitted from sphere to sphere in the
Ptolemaic/Aristotelian model. Aristotelian physics explained all of
those phenomena in ways that made sense of the observational experience
then available. As Butterfield writes:

"In fact, you had to throw over the very frameboard of existing
science, and it was here that Copernicus clearly failed to provide an
alternative. He provided a neater geometry of the heavens, but it was
one which made nonsense of the reasons and explanations that had
previously been given to account for the movements in the sky" (1949,
p. 27).

Of course, Aristotelian physics had difficulties of its own, but
Copernicanism introduced a whole host of new problems, while only
eliminating a few: "Most of the essential elements by which we know the
Copernican Revolution - easy and accurate computations of planetary
position, the abolition of epicycles and eccentrics, the dissolution of
the spheres, the sun a star, the infinite expansion of the universe -
these and many others are not to be found anywhere in Copernicus's
work" (Kuhn, 1957, p. 135).

Nor does the frequent assertion that Copernicus's theory was
significantly simpler than Ptolemy's stand up to scrutiny. As Lakatos
notes:

"The superior simplicity of the Copernican theory was just as much of a
myth as its superior accuracy. The myth of superior simplicity was
dispelled by the careful and professional work of modern historians.
They reminded us that while Copernican theory solves certain problems
in a simpler way than does the Ptolemaic one, the price of the
simplification is unexpected complications in the solution of other
problems. The Copernican system is certainly simpler since it dispenses
with equants and some eccentrics; but each equant and eccentric removed
has to be replaced by new epicycles and epicyclets.... he also has to
put the centre of the universe not at the Sun, as he originally
intended, but at an empty point fairly near to it."

The suggestion that Galileo had all of the evidence on his side in his
battle against the Aristotelians and the Church is also erroneous. In
his book Two Systems one of the major pieces of evidence he advanced
for the Copernican model was the existence of tides. Galileo explained
them as arising from the motion of the Earth rocking the oceans back
and forth, much as a swinging a bucket containing water will slosh the
water up one side of the bucket and then the other.

Of course, this is quite different from our current understanding of
tides as arising from the gravitational influence of the moon. But what
is really surprising about Galileo's hypothesis, given his common
portrayal as a staunch empiricist, is that he had not even investigated
the actual period of the tides before forwarding this argument! His
theory required a 24-hour tidal cycle, while in fact it is 12 hours.
When he learned that sailors in the Mediterranean reported high and low
tides occurring every 12 hours, he explained this glaring discrepancy
as resulting from local variations in the ocean bottom. (See Shea and
Artigas, 2003.)

Galileo also failed to be a "good empiricist" when he ignored his ally
Kepler's theory that the planets orbit the sun in elliptical, rather
than circular, paths. Kepler's model fit the data much better than
Galileo's, yet Kepler's letters to Galileo suggesting elliptical orbits
never even solicited a response.

When one looks at the real history of the Scientific Revolution, it
becomes apparent that observation was rarely the prime impetus for the
development of the most important new theories. Instead, leading
scientists drew their main inspiration from their beliefs about the
kind of world they envisioned that God would create. Copernicus and
Kepler were Neo-Platonists, and it seemed to them that the Sun, the
most brilliant light in our world, was a more fitting center for God's
creation than the Earth. Copernicus was also dissatisfied with the
Ptolemaic model of the heavens because it centered the orbits of
heavenly bodies not on the Earth, the supposed center of the cosmos,
but on a point called the equant, which was an empty spot in space near
to the Earth. Newton was a deeply religious man, who believed that
God's work would naturally exhibit the sort of mathematical perfection
he hoped to reflect in his own theories.

I came across another very common idea about the Scientific Revolution
in browsing a recent issue of National Geographic. Speculating on the
impact of the possible future discovery of other, earth-like planets,
the article's author writes: "It's hard to overstate the excitement
scientists feel at the prospect of seeing that faint blue dot. If it
told of a watery, temperate place, humanity would face a 21st-century
version of Copernicus's realization nearly 500 years ago that the Earth
is not the center of the solar system. The discovery would show 'that
were not in a special place, that we might be part of a continuum of
life in the cosmos, and that life might be very common,' says Michael
Meyer, an astronomer at the University of Arizona."

As a corollary of the above, it's often suggested that many people in
the sixteenth and seventeenth centuries rejected the idea of a
sun-centered solar system because it displaced the Earth from its
unique location at the center of the universe, and therefore seemed to
make humanity less important in the scheme of creation. However,
Professor John Milton, with whom I am studying the history of science
at King's College in London, notes that historians have discovered no
evidence of any of the contemporaries of Copernicus or Galileo voicing
such a concern. And that is not too surprising, when we consider that,
in the prevailing cosmology of the time, the center of the cosmos was
not a very prestigious place to be. Aristotle regarded it as the region
to which gross and corrupt matter gravitated, distinctly inferior to
the unchanging perfection exhibited by the heavens. And in Dante's
Divine Comedy, the occupant of the Earth's center, and therefore at the
precise center of the universe, was none other than Satan himself. To
place the Earth in the heavens was to grant it a promotion.

None of what I have presented above is meant to claim that the
conservatism typical of entrenched interests, for instance, of the
Aristotelians who dominated the universities of the 16th and 17th
centuries, did not present an extra-scientific hurdle that new
conceptions of the physical world had to surmount, or that the Catholic
Church never resisted the progress of science for dogmatic reasons.

But the common, popular version of the history of science, in which
unselfish, heroic scientists do battle with the backward forces of
religion, is a fairy tale, spun mostly by Voltaire and his followers,
in order to discredit the religious belief that they despised. The real
history of the Scientific Revolution is much more complex and nuanced
than the simplistic morality play they made it out to be. If we are
truly interested in understanding the roles that religion and science
have played in creating our civilization, we should put aside the myth
and attend to the reality.

References

Appenzeller, T. (2004) "Search for Other Earths," National Geographic,
Dec. 2004, pp. 68-95.
Butterfield, H. (1949) The Origins of Modern Science: 1300-1800,
London: G. Bell and Sons Ltd.
Kuhn, T.S. (1957) The Copernican Revolution: Planetary Astronomy in the
Development of Western Thought, Cambridge, Massachusetts and London:
Harvard University Press.
Lakatos, I. (1978) The Methodology of Scientific Research Programmes:
Philosophical Papers Volume 1, Cambridge, England: Cambridge University
Press.
Shea, W.R. and M. Artigas (2003) Galileo in Rome: The Rise and Fall of
a Troublesome Genius, Oxford, England: Oxford University Press.
Wessells, N.K and J.L. Hopson (1988) Biology, New York: Random House.
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BM