Philosophy and Nature of Science Part 1. Philosophy Part 2. Philosophers
Basic Questions How do we know? What is knowing? Can we know with certainty? Can we believe something with certainty? Are there facts? Is there truth? Can an hypothesis be verified or falsified?
What Constitutes Evidence? Is there a relationship between evidence and hypothesis? What evidence does one select to establish an hypothesis?
How Does One Do SCIENCE? Science does not adhere to the Baconian procedure of observation before hypothesis, hypothesis before testing. It is more artistically driven. The scientist responds to an observed event by curiosity. The scientist follows up curiosity with persistence having no sure and fixed method to unravel the conundrum. Finally the researcher employs memory to relate one event to another and to avoid redundancy.
Questions asked in the philosophy of science • Is science based on faith? • What is the scientific method? • How are new discoveries treated? • Is everything reducible to physics and mathematics? • Is everything reducible to a few rules?
Science and Faith Some Articles of Faith Science is based on articles of faith: The universe is consistent over space and time. The universe is understandable. We can understand the universe. What’s valid here is valid there. The universe is material and not spiritual The universe is mathematical. Experiment validates theory
What Characterizes science? • A method for retaining reliable knowledge about the universe due to test and retest • Science is a testing community • Science seeks consistency not truth • Science tells the best minimal story about the universe. Pieces fit into a puzzle • Science does not ask why, but asks how, what, where, and when. Science seeks measurement
Ideal Scientific Method • Observation • Repetition • Induction(1) Hypothesis • Deduction or generalization Consequence or prediction • Testing • Induction(2) • Induction (1) not successful
Critique of the Ideal scientific Method • What’s observed and studied depends on the currently accepted explanation • Explanation selects the observation Explanation Influenced by: Brain hardware Gestalt formation Optical illusions Brain Software Education
Induction induction Observation -----------------> Hypothesis
Induction • Induction goes from effect to cause. • Effect can possibly have many causes. • A cause may have a single effect. • Hypothesis is a kind of cause effect cause
Critique of Induction • There is no logical way of going from observation to hypothesis • Hypothesis is a simple guess • Frequently hypothesis precedes observation
Hypothesis, Theory, Fact • Hypothesis are Guesses not logically derivable from deduction or Induction • Theories are statement of Probability • Facts do not exist- nothing is 100% certain
Verification & Falsification • What is meant by explanation? • What is a fact? • When is a Fact verified? • How many observations needed?
Deduction and Induction induction Observation ------------> Hypothesis deduction Hypothesis ------------> Observation
Deduction • If there is no cogent way of going from observation to hypothesis • Then there is no cogent way of deducing from hypothesis to observation
Critique of Deduction • Modern Science does not seek causes but seeks relationship among variables • Independent variables are not causes and dependent variables are not effects • If one knows Y =g(x), can one predict (deduce) the future?
Verification and Falsification • Replace Verification with Falsification • Verification and falsification are asymmetrical • Multiple verification does not establish a theory more than a single verification • A single falsification overturns a theory It takes only one green swan overturns the theory that all swans are white. Observing one million white swans does no more to prove all swans are white than witnessing ten white swans.
Falsification • It is nearly impossible to falsify an hypothesis. • Since a test depends on many factors it is difficult to determine whether the hypothesis failed or one of the other factors failed. • Some failures of dependent factors: precision and accuracy of instrumentation, correct interpretation of data, flawless recording of data, improper experimental conditions
Transition to Immanuel Kant Rationalism and Empiricism
Historical Overview Rationalism Descartes Spinoza Leibniz Wolff Kant Locke Berkeley Hume Empiricism
Empiricism • Basic tenets of Empiricism • All knowledge comes from experience • The mind is a blank slate (tabula rasa) • The mind is passive, merely a receptor of sense impressions • Hume’s radicalizes these, ending in Skepticism • Unbridgeable gap between sense impressions and objects in the world • All we know are ‘sensations’ playing in our minds • The necessary ‘connectedness’ of experience is problematic Causality is merely superstition, born of habit
Rationalism • Basic tenets of Rationalism • Reason has access to reality as it really is • Reason can go beyond what is given to us in experience • Reason can then grasp things, not as they appear, but as they really are • The Leibniz-Wolffian School • Reason (without experience) can know about God, immortality of the soul, and human freedom • Reason has direct access to “meta-physical” knowledge
Part 2 • John Locke • David Hume • Immanuel Kant • Thomas Bayes • Karl Popper • Thomas Kuhn • Imre Lakatos
John Locke (1632-1704) Introduction
Biography • B. 1632, son of a small property-owner and lawyer • Oxford, 1652-67 • Studied church-state issues, chemistry and medicine, new mechanical philosophy • Involvement in politics through Lord Ashley, whom he treated for a liver abscess • Plotted to assassinate King Charles II and his Catholic brother, later James II • Exile in Holland, 1683-89 • 1689: 3 major works published
Major works and themes: A Letter Concerning Toleration (1689) • Argues for religious toleration; • Except for atheists, “who deny the Being of a God” and thus cannot be trusted to keep their promises (e.g. in contracts). Context: - Religious wars and persecution in England and on the Continent.
Works, cont. Essay Concerning Human Understanding (1689) • Argues against innate ideas • For the acquisition of knowledge through the senses: “Intuitionism” • Anti-Cartesian (Descartes) • Re-opens debate about essentialism vs conventionalism with his views on identity, comparison, classification and natural kinds.
Works, cont. Two Treatises on Government (written 1679/80; published 1689/90) • First: Argues against traditional basis for political authority expressed in Filmer’s Patriarcha, divine right of kings; • Second: protection of private property, life and liberty = basis for civil government.
Locke’s Basic Epistemology • Human being = tabula rasa (blank slate) • receives sense-impressions • some of these transformed by Mind into Ideas • Ideas represented in language by words • However, no Ideas are innate • Mind operates (through gradual learning process) w/out reference to any received authority (of Church, State or others)
Complex Ideas • Sense-data of primary qualities (PQs) and secondary qualities (SQs), produce ideas in the mind: • Ideas are mental results of sense-data • -Sense-perceptions • -Bodily sensations • -Mental images • -Thoughts and concepts
Primary(PQ) and Secondary Qualities(SQ) Distinction between perceived aspects of things. The primary qualities are intrinsic features of the thing itself (its size, shape, internal structure, mass, and momentum, for example), while the secondary qualities are merely its powers to produce sensations in us (its color, odor, sound, and taste, for example). This distinction was carefully drawn by Galileo, Descartes, Boyle, and Locke, whose statement of the distinction set the tone for future scientific inquiry. But Foucher, Bayle, and Berkeley argued that the distinction is groundless, so that all sensible qualities exist only in the mind of the perceiver.
Attacks Innatism (Descartes) Locke’s objections to innate ideas (“II’s”) • Lack of universal assent: II’s not known to idiots, children, illiterates • Dependence on authority: • “…a Man is not permitted without Censure to follow his own Thoughts in the search of Truth, when they lead him…out of the common Road”. • Epistemological and political commitment to the individual (who is the foundation of Locke’s political liberalism).
Revised, 11/21/03 David Hume(1711-1776) An Inquiry Concerning Human Understanding
1. Sensation & the Origin of Ideas • The contents of the mind: (1) ideas & (2) impressions (sensations & feelings) -- Ideas (concepts, beliefs, memories, mental images, etc.) are faint & unclear; impressions are strong & vivid. • Ideas are derived from impressions: All ideas are copies of impressions. • The meaning of ideas depends on impressions
The empirical criterion of meaning "From what impression is that alleged idea derived?" No impression, no meaning? No impression, no foundation in reality?
Two kinds of ideas(or judgments) "All the objects of human reason or inquiry may naturally be divided into two kinds: relations of ideas and matters of fact". "Hume's Fork"
Judgments concerning relations of ideas Ideas ("Hume's Fork") Judgments concerning matters of fact
Judgments concerning relations of ideas • Intuitively or demonstrably certain • Discoverable by thought alone [a priori] • Cannot be denied without contradiction *Hume's examples: Pythagorean Theorem or 3 x 5 = 30 2
The Pythagorean Theorem On a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides 5' 4' (hypotenuse) 32 + 42 = 52 (9 + 16 = 25) 3'
Judgments concerning matters of fact • "Every judgment concerning matters of fact can be denied without contradiction" (e.g., "the sun will not rise tomorrow"). • Neither intuitively nor demonstrably certain • Not discoverable by thought alone [a priori], but rather on the basis of sense experience [a posteriori] More specifically,
All judgments concerning matters of fact are based on . . . . the more fundamental] belief that there is "a tie or connection" between cause & effect.
And why do we believe that there is a "tie or connection" between cause & effect? Answer: The belief arises entirely from experience [a posteriori, not a priori], namely, the experience of finding that two events (cause & effect) are "constantly conjoined" with each other.
It is not logically necessary that a particular effect follows a particular cause; it is just a fact of experience. This view leads to Hume's discussion of . . . .
3. The Nature & Limits of Inductive Reasoning (the problem of induction)
Hume on Induction • Induction is the process of drawing inferences from past experiences of cause & effect sequences to present or future events. • Hume's point is that an "effect" cannot be validly deduced from its "cause;" • the inference from "cause" to "effect" is based on past experiences of "constant conjunction," and these past experiences . . . .
accustom or habituate us to believe that one event is the cause of another, which we believe to be the effect of the prior event. This is what leads us to believe that . . . .