The history of scientific method considers
changes in the methodology of scientific inquiry,
as distinct from the history of science itself.
The development of rules for scientific reasoning
has not been straightforward; scientific method
has been the subject of intense and recurring
debate throughout the history of science,
and eminent natural philosophers and scientists
have argued for the primacy of one or another
approach to establishing scientific knowledge.
Despite the disagreements about approaches,
scientific method has advanced in definite
steps. Rationalist explanations of nature,
including atomism, appeared both in ancient
Greece in the thought of Leucippus and Democritus,
and in ancient India, in the Nyaya, Vaisesika
and Buddhist schools, while Charvaka materialism
rejected inference as a source of knowledge
in favour of an empiricism that was always
subject to doubt. Aristotle pioneered scientific
method in ancient Greece alongside his empirical
biology and his work on logic, rejecting a
purely deductive framework in favour of generalisations
made from observations of nature.
Some of the most important debates in the
history of scientific method center on: rationalism,
especially as advocated by René Descartes;
inductivism, which rose to particular prominence
with Isaac Newton and his followers; and hypothetico-deductivism,
which came to the fore in the early 19th century.
In the late 19th and early 20th centuries,
a debate over realism vs. antirealism was
central to discussions of scientific method
as powerful scientific theories extended beyond
the realm of the observable, while in the
mid-20th century some prominent philosophers
argued against any universal rules of science
at all.
== Early methodology ==
There are few explicit discussions of scientific
methodologies in surviving records from early
cultures. The most that can be inferred about
the approaches to undertaking science in this
period stems from descriptions of early investigations
into nature, in the surviving records. An
Egyptian medical textbook, the Edwin Smith
papyrus, (c. 1600 BCE), applies the following
components: examination, diagnosis, treatment
and prognosis, to the treatment of disease,
which display strong parallels to the basic
empirical method of science and according
to G. E. R. Lloyd played a significant role
in the development of this methodology. The
Ebers papyrus (c. 1550 BCE) also contains
evidence of traditional empiricism.
By the middle of the 1st millennium BCE in
Mesopotamia, Babylonian astronomy had evolved
into the earliest example of a scientific
astronomy, as it was "the first and highly
successful attempt at giving a refined mathematical
description of astronomical phenomena." According
to the historian Asger Aaboe, "all subsequent
varieties of scientific astronomy, in the
Hellenistic world, in India, in the Islamic
world, and in the West – if not indeed all
subsequent endeavour in the exact sciences
– depend upon Babylonian astronomy in decisive
and fundamental ways."The early Babylonians
and Egyptians developed much technical knowledge,
crafts, and mathematics used in practical
tasks of divination, as well as a knowledge
of medicine, and made lists of various kinds.
While the Babylonians in particular had engaged
in the earliest forms of an empirical mathematical
science, with their early attempts at mathematically
describing natural phenomena, they generally
lacked underlying rational theories of nature.
It was the ancient Greeks who engaged in the
earliest forms of what is today recognized
as a rational theoretical science, with the
move towards a more rational understanding
of nature which began at least since the Archaic
Period (650 – 480 BCE) with the Presocratic
school. Thales was the first to use natural
explanations, proclaiming that every event
had a natural cause, even though he is known
for saying "all things are full of gods" and
sacrificed an ox when he discovered his theorem.
Leucippus, went on to develop the theory of
atomism – the idea that everything is composed
entirely of various imperishable, indivisible
elements called atoms. This was elaborated
in great detail by Democritus.
Similar atomist ideas emerged independently
among ancient Indian philosophers of the Nyaya,
Vaisesika and Buddhist schools. In particular,
like the Nyaya, Vaisesika, and Buddhist schools,
the Cārvāka epistemology was materialist,
and skeptical enough to admit perception as
the basis for unconditionally true knowledge,
while cautioning that if one could only infer
a truth, then one must also harbor a doubt
about that truth; an inferred truth could
not be unconditional.Towards the middle of
the 5th century BCE, some of the components
of a scientific tradition were already heavily
established, even before Plato, who was an
important contributor to this emerging tradition,
thanks to the development of deductive reasoning,
as propounded by his student, Aristotle. In
Protagoras (318d-f), Plato mentioned the teaching
of arithmetic, astronomy and geometry in schools.
The philosophical ideas of this time were
mostly freed from the constraints of everyday
phenomena and common sense. This denial of
reality as we experience it reached an extreme
in Parmenides who argued that the world is
one and that change and subdivision do not
exist.
In the 3rd and 4th centuries BCE, the Greek
physicians Herophilos (335–280 BCE) and
Erasistratus of Chios employed experiments
to further their medical research; Erasistratus
at one time repeatedly weighing a caged bird,
and noting its weight loss between feeding
times.
=== Aristotle ===
Aristotle's inductive-deductive method used
inductions from observations to infer general
principles, deductions from those principles
to check against further observations, and
more cycles of induction and deduction to
continue the advance of knowledge.The Organon
(Greek: Ὄργανον, meaning "instrument,
tool, organ") is the standard collection of
Aristotle's six works on logic. The name Organon
was given by Aristotle's followers, the Peripatetics.
The order of the works is not chronological
(the chronology is now difficult to determine)
but was deliberately chosen by Theophrastus
to constitute a well-structured system. Indeed,
parts of them seem to be a scheme of a lecture
on logic. The arrangement of the works was
made by Andronicus of Rhodes around 40 BCE.The
Organon comprises the following six works:
The Categories (Greek: Κατηγορίαι,
Latin: Categoriae) introduces Aristotle's
10-fold classification of that which exists:
substance, quantity, quality, relation, place,
time, situation, condition, action, and passion.
On Interpretation (Greek: Περὶ Ἑρμηνείας,
Latin: De Interpretatione) introduces Aristotle's
conception of proposition and judgment, and
the various relations between affirmative,
negative, universal, and particular propositions.
Aristotle discusses the square of opposition
or square of Apuleius in Chapter 7 and its
appendix Chapter 8. Chapter 9 deals with the
problem of future contingents.
The Prior Analytics (Greek: Ἀναλυτικὰ
Πρότερα, Latin: Analytica Priora) introduces
Aristotle's syllogistic method (see term logic),
argues for its correctness, and discusses
inductive inference.
The Posterior Analytics (Greek: Ἀναλυτικὰ
Ὕστερα, Latin: Analytica Posteriora)
deals with demonstration, definition, and
scientific knowledge.
The Topics (Greek: Τοπικά, Latin: Topica)
treats of issues in constructing valid arguments,
and of inference that is probable, rather
than certain. It is in this treatise that
Aristotle mentions the predicables, later
discussed by Porphyry and by the scholastic
logicians.
The Sophistical Refutations (Greek: Περὶ
Σοφιστικῶν Ἐλέγχων, Latin:
De Sophisticis Elenchis) gives a treatment
of logical fallacies, and provides a key link
to Aristotle's work on rhetoric.Aristotle's
Metaphysics has some points of overlap with
the works making up the Organon but is not
traditionally considered part of it; additionally
there are works on logic attributed, with
varying degrees of plausibility, to Aristotle
that were not known to the Peripatetics.
Aristotle introduced what may be called a
scientific method. His demonstration method
is found in Posterior Analytics. He provided
another of the ingredients of scientific tradition:
empiricism. For Aristotle, universal truths
can be known from particular things via induction.
To some extent then, Aristotle reconciles
abstract thought with observation, although
it would be a mistake to imply that Aristotelian
science is empirical in form. Indeed, Aristotle
did not accept that knowledge acquired by
induction could rightly be counted as scientific
knowledge. Nevertheless, induction was for
him a necessary preliminary to the main business
of scientific enquiry, providing the primary
premises required for scientific demonstrations.
Aristotle largely ignored inductive reasoning
in his treatment of scientific enquiry. To
make it clear why this is so, consider this
statement in the Posterior Analytics:
We suppose ourselves to possess unqualified
scientific knowledge of a thing, as opposed
to knowing it in the accidental way in which
the sophist knows, when we think that we know
the cause on which the fact depends, as the
cause of that fact and of no other, and, further,
that the fact could not be other than it is.
It was therefore the work of the philosopher
to demonstrate universal truths and to discover
their causes. While induction was sufficient
for discovering universals by generalization,
it did not succeed in identifying causes.
For this task Aristotle used the tool of deductive
reasoning in the form of syllogisms. Using
the syllogism, scientists could infer new
universal truths from those already established.
Aristotle developed a complete normative approach
to scientific inquiry involving the syllogism,
which he discusses at length in his Posterior
Analytics. A difficulty with this scheme lay
in showing that derived truths have solid
primary premises. Aristotle would not allow
that demonstrations could be circular (supporting
the conclusion by the premises, and the premises
by the conclusion). Nor would he allow an
infinite number of middle terms between the
primary premises and the conclusion. This
leads to the question of how the primary premises
are found or developed, and as mentioned above,
Aristotle allowed that induction would be
required for this task.
Towards the end of the Posterior Analytics,
Aristotle discusses knowledge imparted by
induction.
Thus it is clear that we must get to know
the primary premises by induction; for the
method by which even sense-perception implants
the universal is inductive. [...] it follows
that there will be no scientific knowledge
of the primary premises, and since except
intuition nothing can be truer than scientific
knowledge, it will be intuition that apprehends
the primary premises. [...] If, therefore,
it is the only other kind of true thinking
except scientific knowing, intuition will
be the originative source of scientific knowledge.
The account leaves room for doubt regarding
the nature and extent of Aristotle's empiricism.
In particular, it seems that Aristotle considers
sense-perception only as a vehicle for knowledge
through intuition. He restricted his investigations
in natural history to their natural settings,
such as at the Pyrrha lagoon, now called Kalloni,
at Lesbos. Aristotle and Theophrastus together
formulated the new science of biology, inductively,
case by case, for two years before Aristotle
was called to tutor Alexander. Aristotle performed
no modern-style experiments in the form in
which they appear in today's physics and chemistry
laboratories.
Induction is not afforded the status of scientific
reasoning, and so it is left to intuition
to provide a solid foundation for Aristotle's
science. With that said, Aristotle brings
us somewhat closer an empirical science than
his predecessors.
=== Epicurus ===
In his work Kαvώv ('canon', a straight edge
or ruler, thus any type of measure or standard,
referred to as 'canonic'), Epicurus laid out
his first rule for inquiry in physics: 'that
the first concepts be seen, and that they
not require demonstration '.His second rule
for inquiry was that prior to an investigation,
we are to have self-evident concepts, so that
we might infer [ἔχωμεν οἷς σημειωσόμεθα]
both what is expected [τò προσμένον],
and also what is non-apparent [τò ἄδηλον].Epicurus
applies his method of inference (the use of
observations as signs, Asmis' summary, p.
333: the method of using the phenomena as
signs (σημεῖα) of what is unobserved)
immediately to the atomic theory of Democritus.
In Aristotle's Prior Analytics, Aristotle
himself employs the use of signs. But Epicurus
presented his 'canonic' as rival to Aristotle's
logic. See: Lucretius (c. 99 BCE – c. 55
BCE) De rerum natura (On the nature of things)
a didactic poem explaining Epicurus' philosophy
and physics.
== Emergence of inductive experimental method
==
During the Middle Ages issues of what is now
termed science began to be addressed. There
was greater emphasis on combining theory with
practice in the Islamic world than there had
been in Classical times, and it was common
for those studying the sciences to be artisans
as well, something that had been "considered
an aberration in the ancient world." Islamic
experts in the sciences were often expert
instrument makers who enhanced their powers
of observation and calculation with them.
Muslim scientists used experiment and quantification
to distinguish between competing scientific
theories, set within a generically empirical
orientation, as can be seen in the works of
Jābir ibn Hayyān (721–815) and Alkindus
(801–873) as early examples. Several scientific
methods thus emerged from the medieval Muslim
world by the early 11th century, all of which
emphasized experimentation as well as quantification
to varying degrees.
=== Ibn al-Haytham ===
The Arab physicist Ibn al-Haytham (Alhazen)
used experimentation to obtain the results
in his Book of Optics (1021). He combined
observations, experiments and rational arguments
to support his intromission theory of vision,
in which rays of light are emitted from objects
rather than from the eyes. He used similar
arguments to show that the ancient emission
theory of vision supported by Ptolemy and
Euclid (in which the eyes emit the rays of
light used for seeing), and the ancient intromission
theory supported by Aristotle (where objects
emit physical particles to the eyes), were
both wrong.Experimental evidence supported
most of the propositions in his Book of Optics
and grounded his theories of vision, light
and colour, as well as his research in catoptrics
and dioptrics. His legacy was elaborated through
the 'reforming' of his Optics by Kamal al-Din
al-Farisi (d. c. 1320) in the latter's Kitab
Tanqih al-Manazir (The Revision of [Ibn al-Haytham's]
Optics).Alhazen viewed his scientific studies
as a search for truth: "Truth is sought for
its own sake. And those who are engaged upon
the quest for anything for its own sake are
not interested in other things. Finding the
truth is difficult, and the road to it is
rough. ...Alhazen's work included the conjecture
that "Light travels through transparent bodies
in straight lines only", which he was able
to corroborate only after years of effort.
He stated, "[This] is clearly observed in
the lights which enter into dark rooms through
holes. ... the entering light will be clearly
observable in the dust which fills the air."
He also demonstrated the conjecture by placing
a straight stick or a taut thread next to
the light beam.Ibn al-Haytham also employed
scientific skepticism and emphasized the role
of empiricism. He also explained the role
of induction in syllogism, and criticized
Aristotle for his lack of contribution to
the method of induction, which Ibn al-Haytham
regarded as superior to syllogism, and he
considered induction to be the basic requirement
for true scientific research.Something like
Occam's razor is also present in the Book
of Optics. For example, after demonstrating
that light is generated by luminous objects
and emitted or reflected into the eyes, he
states that therefore "the extramission of
[visual] rays is superfluous and useless."
He may also have been the first scientist
to adopt a form of positivism in his approach.
He wrote that "we do not go beyond experience,
and we cannot be content to use pure concepts
in investigating natural phenomena", and that
the understanding of these cannot be acquired
without mathematics. After assuming that light
is a material substance, he does not further
discuss its nature but confines his investigations
to the diffusion and propagation of light.
The only properties of light he takes into
account are those treatable by geometry and
verifiable by experiment.
=== Al-Biruni ===
The Persian scientist Abū Rayhān al-Bīrūnī
introduced early scientific methods for several
different fields of inquiry during the 1020s
and 1030s. For example, in his treatise on
mineralogy, Kitab al-Jawahir (Book of Precious
Stones), al-Biruni is "the most exact of experimental
scientists", while in the introduction to
his study of India, he declares that "to execute
our project, it has not been possible to follow
the geometric method" and thus became one
of the pioneers of comparative sociology in
insisting on field experience and information.
He also developed an early experimental method
for mechanics.Al-Biruni's methods resembled
the modern scientific method, particularly
in his emphasis on repeated experimentation.
Biruni was concerned with how to conceptualize
and prevent both systematic errors and observational
biases, such as "errors caused by the use
of small instruments and errors made by human
observers." He argued that if instruments
produce errors because of their imperfections
or idiosyncratic qualities, then multiple
observations must be taken, analyzed qualitatively,
and on this basis, arrive at a "common-sense
single value for the constant sought", whether
an arithmetic mean or a "reliable estimate."
In his scientific method, "universals came
out of practical, experimental work" and "theories
are formulated after discoveries", as with
inductivism.
=== Ibn Sina (Avicenna) ===
In the On Demonstration section of The Book
of Healing (1027), the Persian philosopher
and scientist Avicenna (Ibn Sina) discussed
philosophy of science and described an early
scientific method of inquiry. He discussed
Aristotle's Posterior Analytics and significantly
diverged from it on several points. Avicenna
discussed the issue of a proper procedure
for scientific inquiry and the question of
"How does one acquire the first principles
of a science?" He asked how a scientist might
find "the initial axioms or hypotheses of
a deductive science without inferring them
from some more basic premises?" He explained
that the ideal situation is when one grasps
that a "relation holds between the terms,
which would allow for absolute, universal
certainty." Avicenna added two further methods
for finding a first principle: the ancient
Aristotelian method of induction (istiqra),
and the more recent method of examination
and experimentation (tajriba). Avicenna criticized
Aristotelian induction, arguing that "it does
not lead to the absolute, universal, and certain
premises that it purports to provide." In
its place, he advocated "a method of experimentation
as a means for scientific inquiry."Earlier,
in The Canon of Medicine (1025), Avicenna
was also the first to describe what is essentially
methods of agreement, difference and concomitant
variation which are critical to inductive
logic and the scientific method. However,
unlike his contemporary al-Biruni's scientific
method, in which "universals came out of practical,
experimental work" and "theories are formulated
after discoveries", Avicenna developed a scientific
procedure in which "general and universal
questions came first and led to experimental
work." Due to the differences between their
methods, al-Biruni referred to himself as
a mathematical scientist and to Avicenna as
a philosopher, during a debate between the
two scholars.
=== Robert Grosseteste ===
During the European Renaissance of the 12th
century, ideas on scientific methodology,
including Aristotle's empiricism and the experimental
approaches of Alhazen and Avicenna, were introduced
to medieval Europe via Latin translations
of Arabic and Greek texts and commentaries.
Robert Grosseteste's commentary on the Posterior
Analytics places Grosseteste among the first
scholastic thinkers in Europe to understand
Aristotle's vision of the dual nature of scientific
reasoning. Concluding from particular observations
into a universal law, and then back again,
from universal laws to prediction of particulars.
Grosseteste called this "resolution and composition".
Further, Grosseteste said that both paths
should be verified through experimentation
to verify the principles.
=== Roger Bacon ===
Roger Bacon was inspired by the writings of
Grosseteste. In his account of a method, Bacon
described a repeating cycle of observation,
hypothesis, experimentation, and the need
for independent verification. He recorded
the way he had conducted his experiments in
precise detail, perhaps with the idea that
others could reproduce and independently test
his results.
About 1256 he joined the Franciscan Order
and became subject to the Franciscan statute
forbidding Friars from publishing books or
pamphlets without specific approval. After
the accession of Pope Clement IV in 1265,
the Pope granted Bacon a special commission
to write to him on scientific matters. In
eighteen months he completed three large treatises,
the Opus Majus, Opus Minus, and Opus Tertium
which he sent to the Pope. William Whewell
has called Opus Majus at once the Encyclopaedia
and Organon of the 13th century.
Part I (pp. 1–22) treats of the four causes
of error: authority, custom, the opinion of
the unskilled many, and the concealment of
real ignorance by a pretense of knowledge.
Part VI (pp. 445–477) treats of experimental
science, domina omnium scientiarum. There
are two methods of knowledge: the one by argument,
the other by experience. Mere argument is
never sufficient; it may decide a question,
but gives no satisfaction or certainty to
the mind, which can only be convinced by immediate
inspection or intuition, which is what experience
gives.
Experimental science, which in the Opus Tertium
(p. 46) is distinguished from the speculative
sciences and the operative arts, is said to
have three great prerogatives over all sciences:
It verifies their conclusions by direct experiment;
It discovers truths which they could never
reach;
It investigates the secrets of nature, and
opens to us a knowledge of past and future.
Roger Bacon illustrated his method by an investigation
into the nature and cause of the rainbow,
as a specimen of inductive research.
=== Renaissance humanism and medicine ===
Aristotle’s ideas became a framework for
critical debate beginning with absorption
of the Aristotelian texts into the university
curriculum in the first half of the 13th century.
Contributing to this was the success of medieval
theologians in reconciling Aristotelian philosophy
with Christian theology. Within the sciences,
medieval philosophers were not afraid of disagreeing
with Aristotle on many specific issues, although
their disagreements were stated within the
language of Aristotelian philosophy. All medieval
natural philosophers were Aristotelians, but
"Aristotelianism" had become a somewhat broad
and flexible concept. With the end of Middle
Ages, the Renaissance rejection of medieval
traditions coupled with an extreme reverence
for classical sources led to a recovery of
other ancient philosophical traditions, especially
the teachings of Plato. By the 17th century,
those who clung dogmatically to Aristotle's
teachings were faced with several competing
approaches to nature.
The discovery of the Americas at the close
of the 15th century showed the scholars of
Europe that new discoveries could be found
outside of the authoritative works of Aristotle,
Pliny, Galen, and other ancient writers.
Galen of Pergamon (129 – c. 200 AD) had
studied with four schools in antiquity — Platonists,
Aristotelians, Stoics, and Epicureans, and
at Alexandria, the center of medicine at the
time. In his Methodus Medendi, Galen had synthesized
the empirical and dogmatic schools of medicine
into his own method, which was preserved by
Arab scholars. After the translations from
Arabic were critically scrutinized, a backlash
occurred and demand arose in Europe for translations
of Galen's medical text from the original
Greek. Galen's method became very popular
in Europe. Thomas Linacre, the teacher of
Erasmus, thereupon translated Methodus Medendi
from Greek into Latin for a larger audience
in 1519. Limbrick 1988 notes that 630 editions,
translations, and commentaries on Galen were
produced in Europe in the 16th century, eventually
eclipsing Arabic medicine there, and peaking
in 1560, at the time of the scientific revolution.By
the late 15th century, the physician-scholar
Niccolò Leoniceno was finding errors in Pliny's
Natural History. As a physician, Leoniceno
was concerned about these botanical errors
propagating to the materia medica on which
medicines were based. To counter this, a botanical
garden was established at Orto botanico di
Padova, University of Padua (in use for teaching
by 1546), in order that medical students might
have empirical access to the plants of a pharmacopia.
Other Renaissance teaching gardens were established,
notably by the physician Leonhart Fuchs, one
of the founders of botany.The first published
work devoted to the concept of method is Jodocus
Willichius, De methodo omnium artium et disciplinarum
informanda opusculum (1550).
=== Skepticism as a basis for understanding
===
In 1562 "Outlines of Pyrrhonism" by Sextus
Empiricus (c. 160-210 AD) appeared in print
and in Latin, quickly placing the arguments
of classical skepticism in the European mainstream.
Skepticism either denies or strongly doubts
(depending on the school) the possibility
of certain knowledge. Descartes' famous "Cogito"
argument is an attempt to overcome skepticism
and reestablish a foundation for certainty
but other thinkers responded by revising what
the search for knowledge, particularly physical
knowledge, might be.
The first of these, philosopher and physician
Francisco Sanches, was led by his medical
training at Rome, 1571–73, to search for
a true method of knowing (modus sciendi),
as nothing clear can be known by the methods
of Aristotle and his followers — for example,
1) syllogism fails upon circular reasoning;
2) Aristotle's modal logic was not stated
clearly enough for use in medieval times,
and remains a research problem to this day.
Following the physician Galen's method of
medicine, Sanches lists the methods of judgement
and experience, which are faulty in the wrong
hands, and we are left with the bleak statement
That Nothing is Known (1581, in Latin Quod
Nihil Scitur). This challenge was taken up
by René Descartes in the next generation
(1637), but at the least, Sanches warns us
that we ought to refrain from the methods,
summaries, and commentaries on Aristotle,
if we seek scientific knowledge. In this,
he is echoed by Francis Bacon who was influenced
by another prominent exponent of skepticism,
Montaigne; Sanches cites the humanist Juan
Luis Vives who sought a better educational
system, as well as a statement of human rights
as a pathway for improvement of the lot of
the poor.
"Sanches develops his scepticism by means
of an intellectual critique of Aristotelianism,
rather than by an appeal to the history of
human stupidity and the variety and contrariety
of previous theories." —Popkin 1979, p.
37, as cited by Sanches, Limbrick & Thomson
1988, pp. 24–5
"To work, then; and if you know something,
then teach me; I shall be extremely grateful
to you. In the meantime, as I prepare to examine
Things, I shall raise the question anything
is known, and if so, how, in the introductory
passages of another book, a book in which
I will expound, as far as human frailty allows,
the method of knowing. Farewell.
WHAT IS TAUGHT HAS NO MORE STRENGTH THAN IT
DERIVES FROM HIM WHO IS TAUGHT.
WHAT?" —Francisco Sanches (1581) Quod Nihil
Scitur p. 100
=== Francis Bacon's eliminative induction
===
"If a man will begin with certainties, he
shall end in doubts; but if he will be content
to begin with doubts, he shall end in certainties."
—Francis Bacon (1605) The Advancement of
Learning, Book 1, v, 8
Francis Bacon (1561–1626) entered Trinity
College, Cambridge in April 1573, where he
applied himself diligently to the several
sciences as then taught, and came to the conclusion
that the methods employed and the results
attained were alike erroneous; he learned
to despise the current Aristotelian philosophy.
He believed philosophy must be taught its
true purpose, and for this purpose a new method
must be devised. With this conception in his
mind, Bacon left the university.Bacon attempted
to describe a rational procedure for establishing
causation between phenomena based on induction.
Bacon's induction was, however, radically
different than that employed by the Aristotelians.
As Bacon put it,
[A]nother form of induction must be devised
than has hitherto been employed, and it must
be used for proving and discovering not first
principles (as they are called) only, but
also the lesser axioms, and the middle, and
indeed all. For the induction which proceeds
by simple enumeration is childish. —Novum
Organum section CV
Bacon's method relied on experimental histories
to eliminate alternative theories. Bacon explains
how his method is applied in his Novum Organum
(published 1620). In an example he gives on
the examination of the nature of heat, Bacon
creates two tables, the first of which he
names "Table of Essence and Presence", enumerating
the many various circumstances under which
we find heat. In the other table, labelled
"Table of Deviation, or of Absence in Proximity",
he lists circumstances which bear resemblance
to those of the first table except for the
absence of heat. From an analysis of what
he calls the natures (light emitting, heavy,
colored, etc.) of the items in these lists
we are brought to conclusions about the form
nature, or cause, of heat. Those natures which
are always present in the first table, but
never in the second are deemed to be the cause
of heat.
The role experimentation played in this process
was twofold. The most laborious job of the
scientist would be to gather the facts, or
'histories', required to create the tables
of presence and absence. Such histories would
document a mixture of common knowledge and
experimental results. Secondly, experiments
of light, or, as we might say, crucial experiments
would be needed to resolve any remaining ambiguities
over causes.
Bacon showed an uncompromising commitment
to experimentation. Despite this, he did not
make any great scientific discoveries during
his lifetime. This may be because he was not
the most able experimenter. It may also be
because hypothesising plays only a small role
in Bacon's method compared to modern science.
Hypotheses, in Bacon's method, are supposed
to emerge during the process of investigation,
with the help of mathematics and logic. Bacon
gave a substantial but secondary role to mathematics
"which ought only to give definiteness to
natural philosophy, not to generate or give
it birth" (Novum Organum XCVI). An over-emphasis
on axiomatic reasoning had rendered previous
non-empirical philosophy impotent, in Bacon's
view, which was expressed in his Novum Organum:
XIX. There are and can be only two ways of
searching into and discovering truth. The
one flies from the senses and particulars
to the most general axioms, and from these
principles, the truth of which it takes for
settled and immoveable, proceeds to judgment
and to the discovery of middle axioms. And
this way is now in fashion. The other derives
axioms from the senses and particulars, rising
by a gradual and unbroken ascent, so that
it arrives at the most general axioms last
of all. This is the true way, but as yet untried.
In Bacon's utopian novel, The New Atlantis,
the ultimate role is given for inductive reasoning:
Lastly, we have three that raise the former
discoveries by experiments into greater observations,
axioms, and aphorisms. These we call interpreters
of nature.
=== Descartes ===
In 1619, René Descartes began writing his
first major treatise on proper scientific
and philosophical thinking, the unfinished
Rules for the Direction of the Mind. His aim
was to create a complete science that he hoped
would overthrow the Aristotelian system and
establish himself as the sole architect of
a new system of guiding principles for scientific
research.
This work was continued and clarified in his
1637 treatise, Discourse on Method, and in
his 1641 Meditations. Descartes describes
the intriguing and disciplined thought experiments
he used to arrive at the idea we instantly
associate with him: I think therefore I am.
From this foundational thought, Descartes
finds proof of the existence of a God who,
possessing all possible perfections, will
not deceive him provided he resolves "[...] never
to accept anything for true which I did not
clearly know to be such; that is to say, carefully
to avoid precipitancy and prejudice, and to
comprise nothing more in my judgment than
what was presented to my mind so clearly and
distinctly as to exclude all ground of methodic
doubt."This rule allowed Descartes to progress
beyond his own thoughts and judge that there
exist extended bodies outside of his own thoughts.
Descartes published seven sets of objections
to the Meditations from various sources along
with his replies to them. Despite his apparent
departure from the Aristotelian system, a
number of his critics felt that Descartes
had done little more than replace the primary
premises of Aristotle with those of his own.
Descartes says as much himself in a letter
written in 1647 to the translator of Principles
of Philosophy,
a perfect knowledge [...] must necessarily
be deduced from first causes [...] we must
try to deduce from these principles knowledge
of the things which depend on them, that there
be nothing in the whole chain of deductions
deriving from them that is not perfectly manifest.
And again, some years earlier, speaking of
Galileo's physics in a letter to his friend
and critic Mersenne from 1638,
without having considered the first causes
of nature, [Galileo] has merely looked for
the explanations of a few particular effects,
and he has thereby built without foundations.
Whereas Aristotle purported to arrive at his
first principles by induction, Descartes believed
he could obtain them using reason only. In
this sense, he was a Platonist, as he believed
in the innate ideas, as opposed to Aristotle's
blank slate (tabula rasa), and stated that
the seeds of science are inside us.Unlike
Bacon, Descartes successfully applied his
own ideas in practice. He made significant
contributions to science, in particular in
aberration-corrected optics. His work in analytic
geometry was a necessary precedent to differential
calculus and instrumental in bringing mathematical
analysis to bear on scientific matters.
=== Galileo Galilei ===
During the period of religious conservatism
brought about by the Reformation and Counter-Reformation,
Galileo Galilei unveiled his new science of
motion. Neither the contents of Galileo’s
science, nor the methods of study he selected
were in keeping with Aristotelian teachings.
Whereas Aristotle thought that a science should
be demonstrated from first principles, Galileo
had used experiments as a research tool. Galileo
nevertheless presented his treatise in the
form of mathematical demonstrations without
reference to experimental results. It is important
to understand that this in itself was a bold
and innovative step in terms of scientific
method. The usefulness of mathematics in obtaining
scientific results was far from obvious. This
is because mathematics did not lend itself
to the primary pursuit of Aristotelian science:
the discovery of causes.
Whether it is because Galileo was realistic
about the acceptability of presenting experimental
results as evidence or because he himself
had doubts about the epistemological status
of experimental findings is not known. Nevertheless,
it is not in his Latin treatise on motion
that we find reference to experiments, but
in his supplementary dialogues written in
the Italian vernacular. In these dialogues
experimental results are given, although Galileo
may have found them inadequate for persuading
his audience. Thought experiments showing
logical contradictions in Aristotelian thinking,
presented in the skilled rhetoric of Galileo's
dialogue were further enticements for the
reader.
As an example, in the dramatic dialogue titled
Third Day from his Two New Sciences, Galileo
has the characters of the dialogue discuss
an experiment involving two free falling objects
of differing weight. An outline of the Aristotelian
view is offered by the character Simplicio.
For this experiment he expects that "a body
which is ten times as heavy as another will
move ten times as rapidly as the other". The
character Salviati, representing Galileo's
persona in the dialogue, replies by voicing
his doubt that Aristotle ever attempted the
experiment. Salviati then asks the two other
characters of the dialogue to consider a thought
experiment whereby two stones of differing
weights are tied together before being released.
Following Aristotle, Salviati reasons that
"the more rapid one will be partly retarded
by the slower, and the slower will be somewhat
hastened by the swifter". But this leads to
a contradiction, since the two stones together
make a heavier object than either stone apart,
the heavier object should in fact fall with
a speed greater than that of either stone.
From this contradiction, Salviati concludes
that Aristotle must, in fact, be wrong and
the objects will fall at the same speed regardless
of their weight, a conclusion that is borne
out by experiment.
In his 1991 survey of developments in the
modern accumulation of knowledge such as this
Charles Van Doren considers that the Copernican
Revolution really is the Galilean Cartesian
(René Descartes) or simply the Galilean revolution
on account of the courage and depth of change
brought about by the work of Galileo.
=== Isaac Newton ===
Both Bacon and Descartes wanted to provide
a firm foundation for scientific thought that
avoided the deceptions of the mind and senses.
Bacon envisaged that foundation as essentially
empirical, whereas Descartes provides a metaphysical
foundation for knowledge. If there were any
doubts about the direction in which scientific
method would develop, they were set to rest
by the success of Isaac Newton. Implicitly
rejecting Descartes' emphasis on rationalism
in favor of Bacon's empirical approach, he
outlines his four "rules of reasoning" in
the Principia,
We are to admit no more causes of natural
things than such as are both true and sufficient
to explain their appearances.
Therefore to the same natural effects we must,
as far as possible, assign the same causes.
The qualities of bodies, which admit neither
intension nor remission of degrees, and which
are found to belong to all bodies within the
reach of our experiments, are to be esteemed
the universal qualities of all bodies whatsoever.
In experimental philosophy we are to look
upon propositions collected by general induction
from phænomena as accurately or very nearly
true, notwithstanding any contrary hypotheses
that may be imagined, until such time as other
phænomena occur, by which they may either
be made more accurate, or liable to exceptions.
But Newton also left an admonition about a
theory of everything:
To explain all nature is too difficult a task
for any one man or even for any one age. 'Tis
much better to do a little with certainty,
and leave the rest for others that come after
you, than to explain all things.
Newton's work became a model that other sciences
sought to emulate, and his inductive approach
formed the basis for much of natural philosophy
through the 18th and early 19th centuries.
Some methods of reasoning were later systematized
by Mill's Methods (or Mill's canon), which
are five explicit statements of what can be
discarded and what can be kept while building
a hypothesis. George Boole and William Stanley
Jevons also wrote on the principles of reasoning.
== Integrating deductive and inductive method
==
Attempts to systematize a scientific method
were confronted in the mid-18th century by
the problem of induction, a positivist logic
formulation which, in short, asserts that
nothing can be known with certainty except
what is actually observed. David Hume took
empiricism to the skeptical extreme; among
his positions was that there is no logical
necessity that the future should resemble
the past, thus we are unable to justify inductive
reasoning itself by appealing to its past
success. Hume's arguments, of course, came
on the heels of many, many centuries of excessive
speculation upon excessive speculation not
grounded in empirical observation and testing.
Many of Hume's radically skeptical arguments
were argued against, but not resolutely refuted,
by Immanuel Kant's Critique of Pure Reason
in the late 18th century. Hume's arguments
continue to hold a strong lingering influence
and certainly on the consciousness of the
educated classes for the better part of the
19th century when the argument at the time
became the focus on whether or not the inductive
method was valid.
Hans Christian Ørsted, (Ørsted is the Danish
spelling; Oersted in other languages) (1777–1851)
was heavily influenced by Kant, in particular,
Kant's Metaphysische Anfangsgründe der Naturwissenschaft
(Metaphysical Foundations of Natural Science).
The following sections on Ørsted encapsulate
our current, common view of scientific method.
His work appeared in Danish, most accessibly
in public lectures, which he translated into
German, French, English, and occasionally
Latin. But some of his views go beyond Kant:
"In order to achieve completeness in our knowledge
of nature, we must start from two extremes,
from experience and from the intellect itself.
... The former method must conclude with natural
laws, which it has abstracted from experience,
while the latter must begin with principles,
and gradually, as it develops more and more,
it becomes ever more detailed. Of course,
I speak here about the method as manifested
in the process of the human intellect itself,
not as found in textbooks, where the laws
of nature which have been abstracted from
the consequent experiences are placed first
because they are required to explain the experiences.
When the empiricist in his regression towards
general laws of nature meets the metaphysician
in his progression, science will reach its
perfection."Ørsted's "First Introduction
to General Physics" (1811) exemplified the
steps of observation, hypothesis, deduction
and experiment. In 1805, based on his researches
on electromagnetism Ørsted came to believe
that electricity is propagated by undulatory
action (i.e., fluctuation). By 1820, he felt
confident enough in his beliefs that he resolved
to demonstrate them in a public lecture, and
in fact observed a small magnetic effect from
a galvanic circuit (i.e., voltaic circuit),
without rehearsal;In 1831 John Herschel (1792–1871)
published A Preliminary Discourse on the study
of Natural Philosophy, setting out the principles
of science. Measuring and comparing observations
was to be used to find generalisations in
"empirical laws", which described regularities
in phenomena, then natural philosophers were
to work towards the higher aim of finding
a universal "law of nature" which explained
the causes and effects producing such regularities.
An explanatory hypothesis was to be found
by evaluating true causes (Newton's "vera
causae") derived from experience, for example
evidence of past climate change could be due
to changes in the shape of continents, or
to changes in Earth's orbit. Possible causes
could be inferred by analogy to known causes
of similar phenomena. It was essential to
evaluate the importance of a hypothesis; "our
next step in the verification of an induction
must, therefore, consist in extending its
application to cases not originally contemplated;
in studiously varying the circumstances under
which our causes act, with a view to ascertain
whether their effect is general; and in pushing
the application of our laws to extreme cases."William
Whewell (1794–1866) regarded his History
of the Inductive Sciences, from the Earliest
to the Present Time (1837) to be an introduction
to the Philosophy of the Inductive Sciences
(1840) which analyzes the method exemplified
in the formation of ideas. Whewell attempts
to follow Bacon's plan for discovery of an
effectual art of discovery. He named the hypothetico-deductive
method (which Encyclopædia Britannica credits
to Newton); Whewell also coined the term scientist.
Whewell examines ideas and attempts to construct
science by uniting ideas to facts. He analyses
induction into three steps:
the selection of the fundamental idea, such
as space, number, cause, or likeness
a more special modification of those ideas,
such as a circle, a uniform force, etc.
the determination of magnitudesUpon these
follow special techniques applicable for quantity,
such as the method of least squares, curves,
means, and special methods depending on resemblance
(such as pattern matching, the method of gradation,
and the method of natural classification (such
as cladistics).
But no art of discovery, such as Bacon anticipated,
follows, for "invention, sagacity, genius"
are needed at every step. Whewell's sophisticated
concept of science had similarities to that
shown by Herschel, and he considered that
a good hypothesis should connect fields that
had previously been thought unrelated, a process
he called consilience. However, where Herschel
held that the origin of new biological species
would be found in a natural rather than a
miraculous process, Whewell opposed this and
considered that no natural cause had been
shown for adaptation so an unknown divine
cause was appropriate.John Stuart Mill (1806–1873)
was stimulated to publish A System of Logic
(1843) upon reading Whewell's History of the
Inductive Sciences. Mill may be regarded as
the final exponent of the empirical school
of philosophy begun by John Locke, whose fundamental
characteristic is the duty incumbent upon
all thinkers to investigate for themselves
rather than to accept the authority of others.
Knowledge must be based on experience.In the
mid-19th century Claude Bernard was also influential,
especially in bringing the scientific method
to medicine. In his discourse on scientific
method, An Introduction to the Study of Experimental
Medicine (1865), he described what makes a
scientific theory good and what makes a scientist
a true discoverer. Unlike many scientific
writers of his time, Bernard wrote about his
own experiments and thoughts, and used the
first person.William Stanley Jevons' The Principles
of Science: a treatise on logic and scientific
method (1873, 1877) Chapter XII "The Inductive
or Inverse Method", Summary of the Theory
of Inductive Inference, states "Thus there
are but three steps in the process of induction
:-
Framing some hypothesis as to the character
of the general law.
Deducing some consequences of that law.
Observing whether the consequences agree with
the particular tasks under consideration."Jevons
then frames those steps in terms of probability,
which he then applied to economic laws. Ernest
Nagel notes that Jevons and Whewell were not
the first writers to argue for the centrality
of the hypothetico-deductive method in the
logic of science.
=== Charles Sanders Peirce ===
In the late 19th century, Charles Sanders
Peirce proposed a schema that would turn out
to have considerable influence in the further
development of scientific method generally.
Peirce's work quickly accelerated the progress
on several fronts. Firstly, speaking in broader
context in "How to Make Our Ideas Clear" (1878),
Peirce outlined an objectively verifiable
method to test the truth of putative knowledge
on a way that goes beyond mere foundational
alternatives, focusing upon both Deduction
and Induction. He thus placed induction and
deduction in a complementary rather than competitive
context (the latter of which had been the
primary trend at least since David Hume a
century before). Secondly, and of more direct
importance to scientific method, Peirce put
forth the basic schema for hypothesis-testing
that continues to prevail today. Extracting
the theory of inquiry from its raw materials
in classical logic, he refined it in parallel
with the early development of symbolic logic
to address the then-current problems in scientific
reasoning. Peirce examined and articulated
the three fundamental modes of reasoning that
play a role in scientific inquiry today, the
processes that are currently known as abductive,
deductive, and inductive inference. Thirdly,
he played a major role in the progress of
symbolic logic itself – indeed this was
his primary specialty.
Charles S. Peirce was also a pioneer in statistics.
Peirce held that science achieves statistical
probabilities, not certainties, and that chance,
a veering from law, is very real. He assigned
probability to an argument’s conclusion
rather than to a proposition, event, etc.,
as such. Most of his statistical writings
promote the frequency interpretation of probability
(objective ratios of cases), and many of his
writings express skepticism about (and criticize
the use of) probability when such models are
not based on objective randomization. Though
Peirce was largely a frequentist, his possible
world semantics introduced the "propensity"
theory of probability. Peirce (sometimes with
Jastrow) investigated the probability judgments
of experimental subjects, pioneering decision
analysis.
Peirce was one of the founders of statistics.
He formulated modern statistics in "Illustrations
of the Logic of Science" (1877–1878) and
"A Theory of Probable Inference" (1883). With
a repeated measures design, he introduced
blinded, controlled randomized experiments
(before Fisher). He invented an optimal design
for experiments on gravity, in which he "corrected
the means". He used logistic regression, correlation,
and smoothing, and improved the treatment
of outliers. He introduced terms "confidence"
and "likelihood" (before Neyman and Fisher).
(See the historical books of Stephen Stigler.)
Many of Peirce's ideas were later popularized
and developed by Ronald A. Fisher, Jerzy Neyman,
Frank P. Ramsey, Bruno de Finetti, and Karl
Popper.
=== Popper and Kuhn ===
Karl Popper (1902–1994) is generally credited
with providing major improvements in the understanding
of the scientific method in the mid-to-late
20th century. In 1934 Popper published The
Logic of Scientific Discovery, which repudiated
the by then traditional observationalist-inductivist
account of the scientific method. He advocated
empirical falsifiability as the criterion
for distinguishing scientific work from non-science.
According to Popper, scientific theory should
make predictions (preferably predictions not
made by a competing theory) which can be tested
and the theory rejected if these predictions
are shown not to be correct. Following Peirce
and others, he argued that science would best
progress using deductive reasoning as its
primary emphasis, known as critical rationalism.
His astute formulations of logical procedure
helped to rein in the excessive use of inductive
speculation upon inductive speculation, and
also helped to strengthen the conceptual foundations
for today's peer review procedures.Critics
of Popper, chiefly Thomas Kuhn, Paul Feyerabend
and Imre Lakatos, rejected the idea that there
exists a single method that applies to all
science and could account for its progress.
In 1962 Kuhn published the influential book
The Structure of Scientific Revolutions which
suggested that scientists worked within a
series of paradigms, and argued there was
little evidence of scientists actually following
a falsificationist methodology. Kuhn quoted
Max Planck who had said in his autobiography,
"a new scientific truth does not triumph by
convincing its opponents and making them see
the light, but rather because its opponents
eventually die, and a new generation grows
up that is familiar with it."These debates
clearly show that there is no universal agreement
as to what constitutes the "scientific method".
There remain, nonetheless, certain core principles
that are the foundation of scientific inquiry
today.
== Mention of the topic ==
In Quod Nihil Scitur (1581), Francisco Sanches
refers to another book title, De modo sciendi
(on the method of knowing). This work appeared
in Spanish as Método universal de las ciencias.In
1833 Robert and William Chambers published
their 'Chambers's information for the people'.
Under the rubric 'Logic' we find a description
of investigation that is familiar as scientific
method,
Investigation, or the art of inquiring into
the nature of causes and their operation,
is a leading characteristic of reason [...] Investigation
implies three things – Observation, Hypothesis,
and Experiment [...] The first step in the
process, it will be perceived, is to observe...
In 1885, the words "Scientific method" appear
together with a description of the method
in Francis Ellingwood Abbot's 'Scientific
Theism',
Now all the established truths which are formulated
in the multifarious propositions of science
have been won by the use of Scientific Method.
This method consists in essentially three
distinct steps (1) observation and experiment,
(2) hypothesis, (3) verification by fresh
observation and experiment.
The Eleventh Edition of Encyclopædia Britannica
did not include an article on scientific method;
the Thirteenth Edition listed scientific management,
but not method. By the Fifteenth Edition,
a 1-inch article in the Micropædia of Britannica
was part of the 1975 printing, while a fuller
treatment (extending across multiple articles,
and accessible mostly via the index volumes
of Britannica) was available in later printings.
== Current issues ==
In the past few centuries, some statistical
methods have been developed, for reasoning
in the face of uncertainty, as an outgrowth
of methods for eliminating error. This was
an echo of the program of Francis Bacon's
Novum Organum of 1620. Bayesian inference
acknowledges one's ability to alter one's
beliefs in the face of evidence. This has
been called belief revision, or defeasible
reasoning: the models in play during the phases
of scientific method can be reviewed, revisited
and revised, in the light of further evidence.
This arose from the work of Frank P. Ramsey
(1903–1930), of John Maynard Keynes
(1883–1946), and earlier, of William Stanley
Jevons (1835–1882) in economics.
== Science and pseudoscience ==
The question of how science operates and therefore
how to distinguish genuine science from pseudoscience
has importance well beyond scientific circles
or the academic community. In the judicial
system and in public policy controversies,
for example, a study's deviation from accepted
scientific practice is grounds for rejecting
it as junk science or pseudoscience. However,
the high public perception of science means
that pseudoscience is widespread. An advertisement
in which an actor wears a white coat and product
ingredients are given Greek or Latin sounding
names is intended to give the impression of
scientific endorsement. Richard Feynman has
likened pseudoscience to cargo cults in which
many of the external forms are followed, but
the underlying basis is missing: that is,
fringe or alternative theories often present
themselves with a pseudoscientific appearance
to gain acceptance.
== See also ==
Timeline of the history of scientific method
== 
Notes and references ==
== 
Sources ==
Asmis, Elizabeth (January 1984), Epicurus'
Scientific method, 42, Cornell University
Press, p. 386, ISBN 978-0-8014-6682-3, JSTOR
10.7591/j.cttq45z9
Debus, Allen G. (1978), Man and Nature in
the Renaissance, Cambridge: Cambridge University
Press, ISBN 0-521-29328-6
Popkin, Richard H. (1979), The History of
Scepticism from Erasmus to Spinoza, University
of California Press, ISBN 0-520-03876-2
Popkin, Richard H. (2003), The History of
Scepticism from Savonarola to Bayle, Oxford
University Press, ISBN 0-19-510768-3. Third
enlarged edition.
Sanches, Francisco (1636), Opera medica. His
iuncti sunt tratus quidam philosophici non
insubtiles, Toulosae tectosagum as cited by
Sanches, Limbrick & Thomson 1988
Sanches, Francisco (1649), Tractatus philosophici.
Quod Nihil Scitur. De divinatione per somnum,
ad Aristotlem. In lib. Aristoteles Physionomicon
commentarius. De longitudine et brevitate
vitae., Roterodami: ex officina Arnoldi Leers
as cited by Sanches, Limbrick & Thomson 1988
Sanches, Francisco; Limbrick, Elaine. Introduction,
Notes, and Bibliography; Thomson, Douglas
F.S. Latin text established, annotated, and
translated. (1988), That Nothing is Known,
Cambridge: Cambridge University Press, ISBN
0-521-35077-8 Critical edition of Sanches'
Quod Nihil Scitur Latin:(1581, 1618, 1649,
1665), Portuguese:( 1948, 1955, 1957), Spanish:(1944,
1972), French:(1976, 1984), German:(2007)
Vives, Ioannes Lodovicus (1531), De 
Disciplinis libri XX, Antwerpiae: exudebat
M. Hillenius English translation: On Discipline.
Part 1: De causis corruptarum artium,
Part 2: De tradendis disciplinis
Part 3: De artibus
