Lecture Two: Bacons Inductivism and the Scientific Revolution

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Lecture TwoBacons Inductivism and the
Scientific Revolution

• Dr Emma Tobin
• Philosophy
• Bristol

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Course webpage

• http//eis.bris.ac.uk/plemt/
• Powerpoint presentations
• will be uploaded after each lecture!

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Science vs Pseudo-ScienceDemarcation Criteria

• (1) Truth
• (2) Induction from facts
• (3) Assign Probabilities
• (4) Explanatory Power
• (5) Testability
• (6) Falsifiability
• (7) Puzzle-Solving
• Traditionally, scientific theories were
  considered to be true theories.
• So (1) was the chief demarcation criteria.

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Aristotle Cosmology (384-322 BC)

• The Earth is placed at the centre of the cosmos.
• From observing that both the moon and the sun
  appeared to revolve around the earth, Aristotle
  deduced that the earth was at the centre of the
  universe.
• The universe is arranged hierarchically.
• A complete distinction between Earth and the
  Heavens.

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• The Earth (the terrestrial region) was changing,
  subject to decay and composed of concentric
  spheres of the elements earth, air, fire and
  water.
• All bodies moved in straight lines until they
  reached the sphere appropriate to their elemental
  composition.
• The heavens (the celestial region) were eternal
  unchanging and composed of a fifth essence
  (aether) which was moved naturally with circular
  motion by the Prime Mover.

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Scholasticism

• Aristotelian cosmology combined with scholastic
  thought to make science compatible with Christian
  thought.
• Absolute distinction between heaven and earth.
• Making Reason compatible with faith.
• The Aristolelian worldview was compatible with
  the Genesis account of the fall of Adam Eve,
  the distinction between Heaven Earth etc.

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Geocentrism

• The Earth is at the center of the universe and
  the Sun and other celestial objects revolve
  around it.
• The geocentric model was combined with a
  spherical Earth by ancient Greek and medieval
  philosophers.
• Not the same as the older flat Earth model in
  mythology.
• Ptolemy (150 AD) deduced the circuits of the
  planets mathematically. In order to make theory
  and observation concur, he claimed that the
  orbits of the planets had to themselves be in
  circuits that revolved around the earth.

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Ptolemys Geocentrism
In Ptolemy's system the Earth sits
somewhere off the true center of each planets
circular orbit (deferent). Ptolemy attempted to
make the observations of the planets consistent
with a geocentric worldview.
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Heliocentrism The Copernican Revolution

• The Sun is at the center of the universe and the
  Earth and other celestial objects revolve around
  it.
• Copernicus (1473 - 1543) retained Ptolemys
  circular motions, but placed the sun at the
  centre rather than the earth.

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Keplers Model

• Kepler retained the Copernican view of the sun at
  the centre, with the planets rotating around it.
  
• But, made the sun slightly off centre to cohere
  with the orbits of the planets.
• He proposed that planets move in ellipses.
• He postulated his 3 laws of planetary motion.

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The Scientific Revolution

• The heliocentric worldview contradicted Catholic
  doctrine.
• In 1616, the teachings of Copernicus were banned
  by the Vatican.
• The new view of the universe did not cohere as
  comprehensibly with Catholic dogma. (e.g. the
  fall of Adam Eve, the relationship between
  Heaven Earth etc.)

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Common-Sense Objections

• The heliocentric worldview contradicted
  common-sense.
• If the earth turns about its own axis. Then,
  intuitively if we were to drop a stone from a
  high tower, the earth should move beneath it
  while it fell, causing the stone to land away
  from the tower's bottom.
• But, this is contrary to observation.
• The centripetal force exerted by a spinning
  body--especially one that would have to rotate as
  quickly as the Earth would fling objects from its
  surface.
• Newton (1642-1727) would introduce the theory of
  universal gravitation which would explain away
  these anomalies.

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Bacon (1561-1626)
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Bacon The New Method

• Bacon was a great propagandist for the scientific
  revolution.
• In 1620, his book Novum Organun (the new tool)
  proposed a new method for science. see course
  booklet
• Bacon explicitly rejects the deductive method in
  Aristotles Organum.
• He is ambitious about the New Science and the
  possibilities for knowledge about new things.

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The Aristotelian Method

• The tool Deductive logic
• Aristotelian account of knowledge deduction
  from first principles.
• The truth of the conclusion is guaranteed by the
  truth of the premises in a valid argument
• All planets move in ellipses
• Mars is a planet
• ? Mars moves in ellipses
• No expansion of knowledge from the premises to
  the conclusion because knowledge of the
  conclusion is contained in the premises.

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• For Aristotelianism/Scholasticism, only what is
  necessary and could not be otherwise is knowable.
• Humans have access to truths which capture the
  worlds necessity (a priori).
• The role of reason is given primacy over sensory
  experience.
• Metaphysical reasoning reveals scientific truths.
• Knowledge about some fact about the world e.g.
  earth
• All things seek their natural place
• The natural place of the element fire is at the
  top of the
• terrestrial sphere.
• ?Therefore, flames near the surface of the earth
  rise.
• Science is the study of teleology (purposive
  behaviour).
• Science Metaphysics go hand in hand.

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Problems with the Deductive Arguments

• Science aims to generate novel predictions/theorie
  s.
• But, in deductive arguments, we never move beyond
  the premises from the conclusion.
• The role of sensory experience and
  experimentation is marginal.
• Difficult to test the major premise in a
  deductive argument. How do we test P1?
• (P1) All things seek their natural place
• (P2) The natural place of the element fire is at
  the top of the
• terrestrial sphere.
• ?Therefore, flames near the surface of the earth
  rise.

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The Scientific Revolution the birth of
Inductivism

• The Scientific Revolution revealed that the
  truths of science that were revealed by
  deductive reasoning since were false.
• Moreover, a new kind of Science led by
  observation experimentation was generating
  novel predictions of scientific phenomena.

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The Advancement of Science

• The change from a Geocentric to a heliocentric
  view of the world was not the only major
  achievement of the new science.
• Galileo (1564-1642) improved the telescope and
  made important observations in astronomy (e.g.
  the phases of Venus and the moons of Jupiter
  (1610). He developed the laws for falling bodies.
• Harvey (1578-1657) demonstrated that blood
  circulates in experimental dissections.
• Van Leeuwenhoek (1632-1723) engineered the single
  lens microscopes leading to an advancement in
  biology from macrobiology to microbiology.
• Newton (1642-1727) developed calculus and
  proposed the application of the methods of
  mathematics to science. He proposed his theory of
  universal gravitation.

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Bacons Naïve Inductivism

• Bacon proposed induction as a preferable method
  (to Aristotelian deduction) to guarantee progress
  in science.
• Naïve inductivism requires two factors
• Observation (unprejudiced)
• Induction.

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Observation Induction

• Observation must be undertaken free of prejudice
  and background theory.
• The data of observations must be collated in
  observation statements.
• A host of observation sentences collated together
  will result in the formulation (by induction) of
  scientific laws and theories.

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Unprejudiced Observation

• Unprejudiced Observations avoids
• Idols of the Tribe
• Idols of the Cave
• Idols of the Marketplace
• Idols of the Theatre

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Idols of the Tribe

• These are deceptive beliefs innate in the mind of
  man, and therefore belonging to the whole of the
  human race.
• It is the tendency of mankind to exaggerate and
  distort the reality of what they see.
• All human beings perceive more order and
  regularity in nature than there is.

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Idols of the Cave

• These arise within the mind of each individual.
• Imagine that the mind is a cave. When the
  thoughts of each individual enter the cave they
  are corrupted by personality traits, habits and
  tendencies and also by education, and
  environment.

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Idols of the Marketplace

• These arise out of the significance we give to
  the meaning of our words in received language and
  terminology.
• Words and their purported meanings can mislead
  us.
• Words can betray the thoughts that they are used
  to express.

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Idols of the Theatre

• These arise out of a prior commitment to a
  philosophical, scientific or religious belief
  system.
• These belief systems have been handed down from
  authorities and so they are often accepted
  without question.

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Simple Enumerative Induction

• Moves from the observation that instances of some
  phenomena have some characteristic, to the
  conclusion that all instances of that phenomena
  have that characteristic.
• Commonsense examples
• I have observed that (in the past) the sun rose
  in the east and set in the west everyday .
• ?The sun will always rise in the east and set in
  the west.
• In the past, every piece of sugar that I have put
  in tea dissolved.
• ?All sugar dissolves in tea.

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Induction from Observations to Laws

• Keplers 3 laws of planetary motion.
• Inductions from Tycho Brahes naked-eye
  observations of planetary motion.
• Galileos law of free fall (All bodies fall with
  a uniform acceleration).
• Legend has it that Galileo climbed to the top of
  the leaning tower of Pisa and dropped
  simultaneously heavy and light balls. He observed
  that they hit the ground at the same time.
• He induced that All bodies fall with a uniform
  acceleration from these observations.

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Bacons example of Heat

• Table I -Observation Sentences-
• (Instances agreeing in the form of heat)
• The rays of the sun, especially in summer, and at
  noon.
• The same reflected and condensed, as between
  mountains, or on walls, and most of all in
  burning glasses and mirrors.
• Fiery meteors
• Burning thunderbolts
• Eruptions of flames from the cavities of
  mountains.
• All Flame
• Ignited solids.
• Natural warm water baths
• Liquids boiling or heated.
• Bacon gives 20 observation sentences.
• (see course Booklet - Novum Organon - Aphorisms
  Book II XI-XII)

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• Bacon tests these observations by the effect of
  proximity, the degrees of their heat and the
  properties of heat which can be shown to be
  inessential.
• II - Absence of Heat in Proximity (NO -Aphorism
  IIXII)
• (e.g. 1 - The rays of the moon and of the stars
  and comets are not found to be hot to the
  touch.)
• III - Degrees of Heat (Aphorism IIXIII)
• (e.g. 13. All animals in winter and cold weather
  are cold externally, but internally they are
  thought to be even hotter.)
• IV - Properties that are inessential to heat
  (Aphorism IIXVIII)
• (e.g. 6. On account of the rays of the moon and
  other heavenly bodies, with the exception of the
  sun, also reject light and brightness.)

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• From particular observations and consequent
  testing of Heat, Bacon can provide a general
  account of heat by induction.
• Complete rejection of the deductive method in
  favour of observation and experiment.

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Problems with Naïve Inductivism

• When can we legitimately infer a law/theory from
  a set of observation sentences?
• How many observation sentences is enough?
• How can we perform unprejudiced observations?
  Is observation theory-independent?
• Can we assume that the world is uniform?
• Is there a Principle of Induction that
  sanctions our inference from observation
  sentences to universal generalisations? (Humes
  problem)