The aspiration to understanding the world
and being able to explain and predict world
phenomena is connatural to human beings.
Starting from Greek philosophers –like Plato
and Aristotle—philosophers for centuries
reflected on how humans understand the world.
We defined science as a systematically organized
body of knowledge.
But how is such body of knowledge built?
What method do scientists follow?
For centuries what mankind called science
mostly referred to beliefs that had no scientific
justification, but rather came from religion,
superstition or unsupported statements.
They were later found by science to be wrong.
A well known example of a wrong belief is
the Aristotelian and Ptolemaic view, which
placed the earth at the center of the universe.
The notion of scientific method, as we know
it today, was born in the 17th century, with
the work of Francis Bacon, Galileo Galilei
and Isaac Newton.
They developed what we know today as the scientific
method.
The scientific method requires that research
results should be supported by evidence-based
argumentations which must rely on careful
observations of the phenomenon under study.
We now briefly describe their main contributions
to the development of modern science.
Francis Bacon wrote the book “Novum Organum”
(or “New Method”) in 1620, in which he
argues that humans cannot just passively observe
the nature to understand it, they cannot rely
on luck of observations, but need to be proactive
and perform experiments.
Experiments are actions, leading to observations,
performed with the explicit goal of confirming
or refuting a hypothesis that explains a given
natural phenomenon.
Bacon’s ideas fully matured, both in theory
and in practice,
in the fundamental work of Galileo Galilei.
Galileo Galilei was a physicist, an astronomer
and philosopher and is considered as the father
of the scientific method (the father of modern
science, according to Albert Einstein).
He brought Bacon’s thought to maturity and
developed a systematic approach which is based
on observing, collecting, and carefully analyzing
data about the phenomenon under study.
The data are then used to derive whatever
conclusions can be deduced from those data.
He used experiments to disprove or confirm
existing theories.
For example, in his famous Pisa leaning tower
experiment, he dropped two spheres of different
masses from the top of the tower to disprove
what people believed at the time: that heavy
objects fall faster than lighter ones, in
direct proportion to their weight.
A fundamental contribution by Galileo is also
the equal importance
of theory and application in research.
He used tools and built his own tools to support
his research, like his famous telescope used
to observe the geography of the Moon, the
phases of Venus, and the moons of Jupiter.
In building his telescope, he was among the
first to use the refracting principle
to observe the stars.
He also devised and improved a geometric and
military compass suitable for use by gunners
and surveyors, developed a new and safer way
of elevating cannons accurately, and a way
of quickly computing the charge of gunpowder
for cannonballs of different sizes and materials.
Finally, he devised engineering schemes to
alleviate river flooding.
In modern jargon, Galileo was both a “scientist”
and an “engineer.
Galileo taught to us that a scientist does
not try to use the data with the goal of getting
evidence that would confirm previous knowledge,
or would conform to dominant orthodoxy or ideology.
Rational argumentations must be used to arrive
at whatever conclusions a careful analysis
of evidence would suggest.
Galileo was a man of high integrity.
He did not hesitate to contradict the doctrine
of the Catholic Church, which followed the
Ptolemaic view that the earth was at the center
of the solar system.
Galileo had to appear before the Roman Inquisition
in 1615 and then again in 1633
he was accused of heresy.
He was forced to recant his views, and was
sentenced to house arrest
for the rest of his life.
Galileo engaged also in what today we can
call reach-out activities.
He did not just speak to his peer scientists,
but brought his revolutionary theories to society.
He realized that scientists must disseminate
the results of research to the general public,
especially if they have a profound impact
on society.
And this must be done using a rigorous but
understandable language.
In a book titled “Dialog Concerning the
Two Chief World Systems” he presents a discussion
involving three men.
One (named Salviati) advocates the scientific
method,
and presents Galileo’s astronomical views.
Another (named Sagredo) takes a neutral position.
A third (named Simplicio) holds firm on the
geocentric, Ptolemaic view of the cosmos.
Although Galileo did not explicitly conclude
that Salviati is right (and Simplicio is wrong),
all the arguments that refute geocentrism
clearly emerge from his book.
We now briefly introduce Isaac Newton's key
contributions to the scientific method.
Isaac Newton was born the year Galileo died.
He brought the scientific revolution to its
full glory.
Some people consider his book “The Mathematical
Principles of Natural Philosophy”, written
in 1687, as the most important book in modern
history.
It also paved the road for the extensive use
of mathematics in research: through mathematics,
observations can be connected and abstracted into comprehensive theories.
For example, Newton describes his theory,
which explains and predicts the movement of
all bodies in the universe, into the three
well-known laws of mechanics.
Building on the foundations laid by Francis
Bacon, Galileo Galilei, and Isaac Newton,
philosophers and scientists continued to investigate
the nature of science and how science progresses.
We jump two centuries beyond Bacon, to briefly
mention the contributions of an important
philosopher, Karl Popper.
In his famous book “The Logic of Scientific
Discovery”, he argues that scientific theories
are universal propositions that are conjectural
and hypothetical in nature and can only be
validated indirectly by reference to their
consequences.
Popper starts from the observation that no
number of positive outcomes at the level of
experimental testing can confirm a scientific
theory,
but a single counterexample is logically decisive.
This demonstrates the superior role of falsification
as opposed to positive verification.
Popper goes on and defines falsifiability
of a proposition “T” as follows: if “T”
is false, then (in principle), “T” could
be shown to be false,
by observation or by experiment.
He then elected falsifiability as the criterion
of demarcation between what is, and is not,
genuinely scientific: a theory should be considered
scientific if, and only if, it is falsifiable.
History of the scientific thought is a fascinating
subject.
Unfortunately it goes beyond the scope of
this course and we need to limit ourselves
to the essentials and stop here.
