Was Galileo Guilty?

GLEN COVE, NY — Was the Inquisition court that condemned the
Italian physicist and astronomer Galileo wrong? The answer is complex
rather than a simple “yes” or “no.”

The key issue in Galileo’s trial was where the center of the
universe is located. The court believed, as did the 2nd-century Greek
scientist Ptolemy, that the Earth is the center of the universe. Copernicus
and Galileo believed that the Sun was the center of the universe. All
of them believed the universe to be a perfect sphere. Later, Newton
taught that the universe was infinite and hence had no center. Pope
Urban VIII, who enforced the condemnation of Galileo, believed that
we did not know with certainty where the center of the universe is.
This view is supported by Einstein’s discoveries.

A related issue was whether the Earth circles the Sun as Galileo and
Copernicus believed, or whether the Sun circles the Earth as the members
of the court, Ptolemy, and Aristotle believed. Today we know that this
is not a real question. Scientists today understand the motion of one
body only in relation to another body or “fixed” point.
It makes practical sense to describe the motion of the Earth with respect
to the Sun, but one can also describe the motion of the Sun with respect
to the Earth. Before he was elected Pope Benedict XVI gave a talk in
which he said there were four different answers to this question.

In 1543, the year of his death, Copernicus published in book form
his theory that the Sun was the center of the universe and that the
Earth rotated daily and orbited the Sun annually. Although some critics
believed the widely read book was heretical, it was circulated in the
Catholic world for 63 years. In 1616, as a result of Inquisition proceedings
against Galileo, the Church condemned nine sentences in Copernicus’ book,
including 10 lines of the preface, and required the publication of
an expurgated version.

Galileo was a proponent of Copernicus’ system. In 1613, Galileo
wrote to Father Benedetto Castello, a monk and mathematician, defending
Copernicus. In his letter, among other objectionable statements, he
said that Scripture contained many false propositions in the “naked
sense” of its words. Father Tomasso Caccini, a Florentine Dominican,
preached against this statement, and Galileo lined up support for himself,
especially among Jesuits. Another Florentine Dominican, Father Nicolo
Lorini, sent a copy of the offending letter to the Roman Inquisition.

These first proceedings before the Roman Inquisition resulted in
a compromise. Galileo was not found guilty of anything, but he was
officially forbidden by Cardinal Bellarmine to teach the Copernican
theory in any way. The Congregation of the Index required that Copernicus’ book
and that of his disciple de Zuniga be corrected before they could again
be sold. A more theologically offensive book defending Copernicus by
a Carmelite priest, Father Paolo Antonio Foscarini, was condemned and
prohibited.

Shortly thereafter, Galileo got in a dispute with some Jesuits concerning
the nature of comets and lost the support of many Jesuits, who had
been his strongest supporters. The new Pope Urban VIII sided with Galileo
in this controversy. Urban VIII apparently hoped that Galileo would
write a book that would present the arguments for both the Copernican
system and the Ptolemaic system in a fair and balanced way, providing
a basis for future scholarship.

Galileo did write a book on that subject in 1632, but it was his
downfall. Although it was in the form of a dialogue between a Copernican
and a Ptolemaist, it was written in such a way as to make all the Copernican
arguments seem sensible and the contrary arguments seem absurd. Moreover,
it ridiculed the Pope’s view that man did not yet know which
system was the true one. This alienated the Pope, until then a supporter.
Furthermore, Galileo argued that the tides proved the theory of Copernicus,
an argument already disproven by Kepler. Galileo’s argument that
the Earth’s magnetism proved the Copernican theory was another
desperate stretch.

Although Galileo negotiated permission to publish the book from both
the Roman and Florentine censors, its publication resulted in new Inquisition
proceedings against him. His defense was a disaster. He argued that
his book only defended the Copernican system as a hypothesis. After
that argument failed, he maintained that he had forgotten that he was
ordered not to teach the Copernican system in any manner, because a
certain certificate given him by Cardinal Bellarmine to help him counter
slanders against him did not mention this prohibition.

The Inquisition had abundant expert evidence that his book violated
the prior order to him. Some of this expert evidence distinguished
Copernicus’ mathematical hypothesis to explain the heavenly bodies
from Galileo’s more concrete arguments, holding Galileo’s
opinions heretical. The Inquisition judged as heretical the opinion
that the Sun was the center of the universe and immobile; it also judged
as absurd the opinion that the Earth was not the center of the universe
and mobile. The Inquisition sentence was a compromise. He was judged
to be vehemently suspect of heresy, placed under indefinite arrest,
required to pray the seven penitential psalms every week for three
years, and required to abjure his teachings about the Sun and Earth.
He was not found guilty of maliciously violating the prior order or
of formal heresy.

After a long trip home, with a stop in Siena, where the Archbishop
was friendly, Galileo spent the rest of his life in the village of
Arcetri. This is usually referred to as “house arrest,” but
he was free to walk around the village and visit his daughters who
were nuns in a convent there. He was limited in the scholars he was
allowed to entertain, but his condition was more like internal exile
than house arrest. The requirement that he abjure his prior opinions
was something of a public disgrace.

One of the ironies of the Galileo case is that if either Galileo
or the Inquisition had applied his discoveries concerning the motion
of bodies to the heavenly bodies, as Newton and Descartes later did,
they might have found common ground.

Galileo has been gradually but completely rehabilitated. It would
be a mistake, however, to put no blame at all on him for his condemnation.

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