Galileo Galilei
The XVII Century
The Scientific Treatise
• Objective of the treatise:
a) to demonstrate a thesis
b) to refute an opposing one
c) to propose a model
• Topologies of the Treatise
a) the debate on the concept of literature and poetics
b) the methodological approaches of the new science
c) the political debate (Machiavelli’s thought)
d) the moral and religious treatise (Counter
e) general treatises on architecture, hydraulics,
military art
• Can the scientific treatise be studied as a literary form?
• What is literature? Expression and formalization of the
imaginary and of subjectivity . In this system
a) the expressive level prevails over the referential
b) connotation (subjective “violence” on language) prevails
over the simple denotation (description of event, object,
• Enrico Falqui Anthology of the Italian Scientific Prose of the
• Latest concepts of scientific treatises:
a) aesthetic value is not the determining factor
b) the inclusion of the scientific perspective opens up
literature to a variety of codes and forms
c) scientific texts play an important role as they associate the
history of culture to that of scientific thought in its
epistemological and sociological implications
d) science creates a multiplicity of languages that enrich
• 1564 Born in Pisa
• 1580 studies medicine and mathematics at the
University of Pisa
• 1585 abandons the university and dedicates himself
to independent studies. Invents the Hydrostatic scale.
Completes studies on the weight of solid matter
• 1589-92 starts to teach mathematics at Pisa
• 1592-1610 teaches mathematics at Padua. Meets
scholars like Paolo Sarpi and Giovan Francesco
Sagredo. Has three children with Marina Gamba:
Virginia, Livia and Vincenzo
• Perfects the telescope and directs his research to the
• Discovers the rough geology of the moon, the nature
of the stellar matter, four of Jupiter’s satellites. The
discovery of the mutability and corruptibility of the
sky is a confutation of Aristotelian cosmology.
• 1610 publishes Sidereus nuncius. Acclaim and
criticism follow. Receives tenure at Pisa
• 1611 travels to Rome to meet the Jesuit astronomer
Clavio (Cristoforo Klan)
• 1612-13 his discoveries appear contrary to the
doctrines of the church
• 1615 his theories appear to be heretical to the
Dominicans who denounce him to the Inquisition
• 1616 the Inquisition condemns Galileo and the
Copernican system. He can no longer teach them
• 1623 publishes Il Saggiatore. It is a polemic answer
to some of Orazio Grassi’s essays about the genesis
and nature of three comets that had appeared in 1618
• The election of Urban VIII (Maffeo Barberini) gives
Galileo new hopes
• 1624 Urban VIII welcomes him in Rome. Starts to
write the Dialogue on the Two Chief Astronomical
• 1632 the Dialogue is published amid polemics and
enthusiasms. In the same year Galileo is in front of
the Holy Office (Inquisition)
• 1634 he must abjure his theories but continues to
• 1638 completes his masterpiece, New Sciences
• 1642 dies in his house of Arcetri
• Il saggiatore ( a special scale)Rebuttal of Grassi’s theories
on the apparition of the three comets (Libra astronomica ac
• It is in Italian rather than in Latin. The title is a metaphor
(not a libra we need but a very precise instrument, a
• The work establishes for the first time the need for a
methodological approach in the observation of
astronomical events
• It refutes the possibility of arriving to the truth by
accepting the wisdom of the ancient philosophers
• The mathematical method will help to understand “il
grandissimo libro dell’universo” that is written in “lingua
matematica” and whose characters are “triangles, circles,
and other geometrical figures without which it is like
wandering in an obscure labyrinth
• The methodological and mathematical approach brings
Galileo to a further discovery: bodies have two different
• Primary (objective) and secondary (subjective) qualities
• The primary qualities are calculable as far as the extension,
the geometrical figure, the movement
• The secondary ones are secondary and subjective, they regard
all the sensorial qualities (color, taste, odor etc.)
• The secondary qualities are the result of the encounter
between these bodies and the human being, they are not
inherent qualities of the bodies. The are real as far as they are
perceived by man
• In this way he refutes the Aristotelian method, based for the
most part on these sensorial qualities (warm and cold etc.).
These are confused notions in his mind, they do not lead to a
scientific knowledge
• In order to understand phenomena in a more objective and
quantitative way, instituting the idea of “measure” which he
utilizes in the observation and calculation of phenomena
• It is following this method that he was able to invent the water
thermometer and reduce the sensations of warm and cold to an
objective and mathematical control
• Important!!!
• Galileo adopts the “vulgar” Italian (antagonistic)
• His terminology reflects a process of simplification
(antagonistic to the difficult and obscure language of traditional
treatises) The word has to reflect the object
• The choice of the dialogue instead of the solid and systematic
model: proof of how the scientific method has transformed the
literary form. The Galilean method is based on research,
hypothesis, verification and therefore it requires discussion,
confrontation, the clashing of opposing views.
• The treatise becomes the dialogue (dialectic)
Galileo’s Trial
Two objectives of Galileo’s Dialogue
Reception of the Dialogue
Reasons for Urban VIII’s change of heart
Galileo’s Reactions to the order of the Holy
Why was Galileo afflicted after his talk with
Where lay the main difficulty of the accusation
Galileo’s confession
The sentence on June 22nd, 1633
The Return to Pure Science
• 1633 -10 months in Siena, as guest at the palace of
Archbishop Piccolomini
• 1633 Return to Arcetri, solitude, loss of Celeste
• 1634-38 Ignorance root of all ills. Science as path
to the truth
• Galileo’s works travel beyond the Alps
• 1638 N. S. appears in Leyden (Elzevirs) He is blind
• The Two New Sciences reworking and expansion
of his Paduan studies (dialogue - testament)
• The treatise on motion (continuously reworked)
• Interlocutors in the dialogue: Salviati, Sagredo,
• First two days: fragmentary investigations, unboroken
succession of debates, on different subjects, digressions,
acute observations
• The next two days: new literary device Salviati reads
aloud a Latin treatise on motion (by Galileo). The
reading is only occasionally interrupted for
clarifications by the interlocutors
• The Beginning of Fifth Day was published in 1674
• The Sixth Day(fragment) published in 1718
• Theme of the first two days: the mechanical resistance
(strength) of materials
• Polemic against Aristotelian mechanics: for Galileo
motion is possible in a vacuum
• Speed of fall of weights: “if the resistance of the medium is
removed, all bodies will fall with equal speed.”
• The vibrations of the pendulum and related acoustic
phenomena are studied
• The Second Day is dedicated to statics (resistance)
• The third and Fourth days are dedicated to dynamics
(totally new science as to the results and the methods
• Fifth and Sixth days are incomplete (the fifth is concerned
with the Euclidean theory of proportion - the sixth with the
problem of the force of percussion)
• Mathematics (as a means and not an end in itself) is linked
with technology, design, the study of natural phenomena
• The Two New Sciences is a Copernican work; in it Galileo
perfects his theory of motion, using the laws of inertia
and acceleration to prove his beliefs
• It is not a Copernican manifesto, rather a work
developed entirely in accordance with the new
Copernican direction of modern science, deepening its
principles and broadening its development (more import
is given to mathematics than in earlier works experience and logic had prevailed there)
• Sagredo affirms that to understand mathematically the
cause of an event “far outweighs the mere data obtained
from the testimony of others, or even from repeated
experiments.” Does experience play a subsidiary role in
Galilean method?
• Although Galileo’s method rests upon the experience, it has
as its primary goal the resolution of observational data into
general relations of a conceptual rather than an empirical
nature. (Ernst Cassirer)
• In Galileo’s research processes the more important task
falls to reason. By determining the mathematical relations
between one experience and another, reason teaches us to
“transform the empirical accident into a necessity governed
by laws.
• Galileo never confused mathematical deduction with
physical demonstration. He understood the difference
between hypothetical truth and factual truth
• Throughout his works he oscillates between recourse to the
purest deductive method and energetic appeal to empirical
• Galileo intuitively senses the complexity of the problem of
method and thus refrains from any dogmatic position,
rationalist or empiricist

Galileo Galilei - TCNJ | The College of New Jersey