Philosophy And Nature Of Science

Philosophy and Nature of Science Part 1. Part 2.

Philosophy 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.

Where art Comes In Abstraction and Synthesis Scientists cut up nature into parts. They study the parts as if they were actual parts of the physical world. Once confident they the scientists understand the part, then combine the parts to “synthesize’ or to reconstitute nature.

Experienced and not Experienced Things experienced implies facts and knowing. The world of knowledge divides into the experienced and the non-experienced What does it mean to have non-experienced knowledge? If we don’t experience, can we know anything? Kant distinguished between pure and empirical knowledge; i.e., a priori &.a posteriori knowledge

Philosophy of Science Concerns Observation, Hypothesis, induction, Falsification, Theory Explanation

Science divides into Methods and Applications • Method - Procedures for acquiring knowledge • Application - Use and purpose of discoveries

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 Science is based on faith. Some Articles of Faith : The universe is constent 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 language of the universe is mathematics. Experiment validates theory

What Characterizes science? • A method for retaining reliable knowledge about the universe is 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

cause

effect

Critique of Induction • There is no logical way of going from observation to hypothesis • Hypothesis is a simple guess • Frequently hypothesis precedes observation

Maybe Hypotheses should be considered only as Statements of Probability • The universe is a series of stochastic events with ill-defined boundaries • An hypothesis is neither true nor false. It is a statement of probability for success or failure. • Replace “All swans are white” with “What is the probability of finding a green or black or blue swan?”

Genealogy of Certainty •

Hypothesis --> Theory --> Fact

INCREASING CERTAINTY

Gloss • A Law is a late 18th and early19th century way of saying theory: LAW = THEORY • Theory gives a mathematical relationship between observable dependent and observable independent variables. The distinction between independent and dependent variable is arbitrary. • Hypothesis gives a mathematical relationship between non-observable and observable variables

Are These: Explanations, Hypotheses,Theories, or Facts? • • • • • • • • •

2nd Law of Thermodynamics Newton’s Law of Universal Gravitation Gas Law Ohm’s Law Electromagnetic Theory Kinetic Gas Theory Atomic Theory Theory of Relativity String Theory

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?

Form Hypothesis I put a balloon in my refrigerator and funny things happened. I really need an explanation.

First the balloon shriveled up. Next, the balloon changed color from red to blue. Finally the balloon said, “Get me out of here, I’m cold!”

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

What is an Explanation? • Hypothesis is not always an explanation • Explanations reference non-observables • Science explains objective reality in terms of a non-objective, non-observable reality • Among non-observable objects are electrons, quarks, photons, gluons, gravitons, positrons, black holes, dark matter, dark energy

Explanation • Explanation is to ask a quantifiable question • Explanation is not to ask a “why” question • Explanation is a sequence of events. • Is an explanation at all posible?

Explanation Pathway vs. Endpoints

Limits of Explanation • The ultimate building blocks of the universe do not interact with our instruments at all or else interact too strongly so that physical nature alters. • It is possible we are at the end of traditional empiricism where observations suggest for or else test for hypothesis. • String theory perhaps is an harbinger of post-scientism wherein hypothesis and observation formally separate.

Theory Have Limits of Application • • • • •

Ptolemaic Astronomy replaced by Copernican Astronomy replaced by Newtonian Astronomy replaced by Einsteinium Astronomy replaced by Quantum Gravity Theory

Overall Criteria for Theories • • • • • • •

Consistent Parsimonious Correlative Empirically Testable (verifiable& falsifiable) Useful Progressive Retrogressive

Transition to Immanuel Kant Rationalism and Empiricism

Historical Overview Rationalism

Descartes

Locke

Spinoza

Leibniz

Berkeley

Hume

Empiricism

Wolff

Kant

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 •

metaphysics: a theory of the essence of things, of the fundamental principles that organize the universe

Part 2 • • • • • • • •

John Locke David Hume Immanuel Kant Thomas Bayes Karl Popper Thomas Kuhn Imre Lakatos Paul Feyerabend

John Locke (1632-1704) Introduction

John Locke

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.

Definitions essentialism conventionalism identity comparison, classification natural kinds.

Essentialism Plato was an essentialist since he believed in ideal forms of which every object is just a poor copy. Ideas are eternal. Ideas are superior to material objects. When we see objects in the material world, we understand them through their relationships between them.

Conventionalism • Belief that judgments of a specific sort are grounded only on (explicit or implicit) agreements in human society, rather than by reference to external reality. Although this view is commonly held with respect to the rules of grammar and the principles of etiquette, its application to the propositions of law, ethics, science, mathematics, and logic is more controversial.

identity • The logical relation of numerical sameness, in which each thing stands only to itself. Although everything is what it is and not anything else, philosophers try to formulate more precisely the criteria by means of which we may be sure that one and the same thing is cognized under two different descriptions or at two distinct times. Leibniz held that numerical identity is equivalent to indiscernibility or sameness of all the features each thing has. But Locke maintained that judgments of identity are invariably made by reference to types or sorts of things. The identity of individual persons is an especially troublesome case.

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

Anthem1

Anthem2

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?

The Nature & Limits of Human Knowledge

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) 2

2

2

3 +4 =5 (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 . . . .

the future will resemble the past. It is all a matter of CUSTOM or HABIT. This is the foundation of . . . .

The Idea that there is a Necessary Connection between Cause & Effect If this is a meaningful (& true?) idea, then (according to Hume) it must be derived from sense impressions. What, then, is the sense impression from which this idea is derived?

There is no sense impression of causal power or necessary connection of cause & effect, but we do experience . . . . (1) the spatial contiguity, (2) the temporal succession, and (3) the constant conjunction

of "cause" & "effect."

It is from this experience,  especially the experience of constant conjunction,  that the idea of a necessary connection between "cause" & "effect" arises (or is inferred);  but the "inference" is simply a matter of "custom or habit."  This seems to mean that the "inference" here is psychological rather than logical. Actually, there is no experience of the necessary connection between cause and effect. Thus, all factual judgments (which are based on the assumption that there is a necessary connection between cause and effect) are subject to doubt.  No necessity, no certainty.

Groundwork of the Metaphysics of Morals

Immanuel Kant • 1724-1804 • Lutheran (Pietist) background • “Second Copernican Revolution”

in philosophy • Spent all his life in Königsberg, a

small German town on the Baltic Sea in East Prussia. (After World War II, Germany's border was pushed west, so Königsberg is now called Kaliningrad and is part of Russia.)

Groundwork of the Metaphysics of Morals

Immanuel Kant • At the age of fifty-five, Kant had published much work on the natural sciences, taught at Königsberg University for over twenty years, and achieved a good reputation in German literary circles. • During the last twenty-five years of his life, however, Kant's philosophical work placed him firmly in the company of such towering giants as Plato and Aristotle.

Groundwork of the Metaphysics of Morals

Immanuel Kant • Kant's three major works are often considered to be the starting points for different branches of modern philosophy: the Critique of Pure Reason (1781) for the philosophy of mind; the Critique of Practical Reason (1788) for moral philosophy; and the Critique of Judgment (1790) for aesthetics.

Groundwork of the Metaphysics of Morals

Immanuel Kant • The Grounding for the Metaphysics of Morals was published in 1785, just before the Critique of Practical Reason. • It is essentially a short introduction to the

argument presented in the second Critique.

Groundwork of the Metaphysics of Morals

Kant’s Intellectual Climate • Kant lived and wrote during the Enlightenment. This period produced the ideas about human rights and democracy that inspired the French and American revolutions. (Some other major figures of the Enlightenment were Locke, Hume, Rousseau and Leibniz.) • The characteristic quality of the Enlightenment was

an immense confidence in reason, i.e. humanity's ability to solve problems through logical analysis. The central metaphor of the Enlightenment was a notion of the light of reason dispelling the darkness of mythology and misunderstanding.

Groundwork of the Metaphysics of Morals

Kant’s Intellectual Climate • Enlightenment thinkers like Kant felt that history had placed them in the unique position of being able to provide clear reasons and arguments for their beliefs. • The ideas of earlier generations, they thought, had

been determined by myths and traditions; their own ideas were based on reason. (According to this way of thinking, the French monarchy's claims to power were based on tradition; reason prescribed a republican government like that created by the revolution.)

Groundwork of the Metaphysics of Morals

Kant • Kant's philosophical goal was to use logical analysis to understand reason itself. Before we go about analyzing our world, Kant argued, we must understand the mental tools we will be using. • In the Critique of Pure Reason, Kant set about developing a comprehensive picture of how our mind – our reason – receives and processes information.

Groundwork of the Metaphysics of Morals

Kant • Kant later said that the great Scottish philosopher David Hume (1711-1776) had inspired him to undertake this project. Hume, Kant said, awoke him from an intellectual "slumber." • The idea that so inspired Kant

was Hume's analysis of cause-andeffect relationships.

Groundwork of the Metaphysics of Morals

Hume According to Hume, when we talk about events in the world we say that one thing ‘causes’ another. But nothing in our perceptions tells us that anything causes anything else. All we know from our perceptions is that certain events regularly occur immediately after certain other events. ‘Causation’ is just a concept that we employ to make sense of why certain events regularly follow certain other events.

Groundwork of the Metaphysics of Morals

Kant • Kant took Hume's idea and went one step further. Causation, Kant argues, is not just an idea that we employ to make sense of our perceptions. It is a concept that we cannot help but employ. We don't sit around watching events and then develop an idea of causation on the basis of what we see. We automatically bring the concept to bear on the situation.

Groundwork of the Metaphysics of Morals

Kant • Kant argued that causation and a number of other basic ideas (e.g., time and space) are hardwired, as it were, into our minds. Anytime we try to understand what we see, we cannot help but think in terms of causes and effects.

Groundwork of the Metaphysics of Morals

Kant Kant's argument has huge implications. If our picture of the world is structured by concepts that are hardwired into our minds, then we can't know anything about how the world ‘really’ is. The world we know about is developed by combining sensory data (‘appearances’ or ‘phenomena,’ as Kant called them) with fundamental concepts of reason (‘causation,’ etc.). We don't know anything about the ‘things-inthemselves’ from which sensory data emanates.

Groundwork of the Metaphysics of Morals

Kant • This recognition that our understanding of the world may have as much to do with our minds as with the world has been called a “Copernican Revolution” in philosophy – a change in perspective as significant to philosophy as Copernicus’s recognition that the earth is not the center of the universe.

Groundwork of the Metaphysics of Morals

Kant • Kant's insights posed a severe challenge to many earlier ideas. Ex.: Before Kant many philosophers offered ‘proofs’ of the existence of God. One argument made was that there must be a "first cause" for the universe. Kant pointed out that the question of whether there "must" be a first cause for the universe is irrelevant, because it is really a question about how we understand the world, not a question about the world itself.

Groundwork of the Metaphysics of Morals

Kant • Kant’s analysis similarly shifted the debate over free will and determinism. (Kant presents a version of this argument in Chapter 3 of the Groundwork.) When we use reason to understand why we have made the choices we have, we can come up with a causal explanation. But this picture is not necessarily accurate. We don't know anything about how things "really" are; we are free to think that we can make free choices, because for all we know this might "really" be the case.

Groundwork of the Metaphysics of Morals

Kant • In the Critique of Practical Reason and the Grounding for the Metaphysics of Morals, Kant applies this same technique –using reason to analyze itself – to determine what moral choices we should make. • Just as we cannot rely on our picture of the world

for knowledge about how the world "really" is, so also we cannot rely on expectations about events in the world in developing moral principles. Kant tries to develop a moral philosophy that depends only on the fundamental concepts of reason.

Groundwork of the Metaphysics of Morals

Kant’s Intellectual Climate: Criticisms Some later thinkers have criticized Enlightenment philosophers like Kant for placing too much confidence in reason. Some have argued that rational analysis is not the best way to deal with moral questions. Further, some have argued that Enlightenment thinkers were pompous to think that they could discover the timeless truths of reason; in fact, their ideas were determined by their culture just as all other people’s are.

Karl Popper

• Popper replaces induction with falsification • Science is not distinguished from non-science on basis of methodology. No unique methodology specific to science • Science consists mostly of problem solving.

Karl Popper • All observations are selective and theory laden • A demarcation between science and pseudoscience is established by falsification. A theory is scientific only if it is refutable by a conceivable event • Every genuine test of a scientific theory is based on an asymmetry between verification and falsification

Sir Karl Popper (1902-1994) • Falsification is the idea that science advances by unjustified, exaggerated guesses followed by unstinting criticism. • Any "positive support" for theories is both unobtainable and superfluous; all we can and need do is create theories and eliminate error • Scientists never actually use induction. It is impossible to verify propositions by reference to experience

Falsificationism (1) Scientific Method •

Is there a scientific method?

•

What justifies scientific claims to knowledge?

•

Can we distinguish scientific method from nonscientific ways of thinking? (demarcation)

•

Does science progress?

Falsificationism (1) Falsificationism ‘No criterion of truth’: Two Arguments: 2. No Theory/observation distinction: • ‘Here is a glass of water’ is theory laden • In accepting the statement we must accept a significant amount of theory • We have only as much justification for accepting the observation statement as we do for the theory

Falsificationism (1) Falsificationism ‘No criterion of truth’: Two Arguments: 2. No Theory/observation distinction: Upshot: we cannot use observation to establish the truth of a theory How can we establish the truth of scientific theories?

We can’t!

Falsificationism (1) Confirmation and Pseudoscience Good scientific practice: E.g. Einstein’s general relativity Conjecture: mass of the sun bends the path of light Apparent location

Actual location

moon

Falsificationism (1) Confirmation and Pseudoscience Good scientific practice: E.g. Einstein’s general relativity Conjecture: mass of the sun bends the path of light • If the apparent location of the observed star doesn’t shift, the theory is wrong. • It will have been refuted. • The mark of a scientific theory is whether it can be falsified by observation

Falsificationism (1) Conjecture and Refutation: “Falsificationists… prefer an attempt to solve an interesting problem by a bold conjecture, even (and especially) if it soon turns out to be false, to any recital of a sequence of irrelevant truisms” (CR: 231) This gives us: (i) a glimpse of scientific method (ii) a demarcation criterion for science

Falsificationism (1) Scientific method: Scientific theories have deductive consequences T: Sodium burns with a yellow flame Obs: This is a piece of sodium Pred: This burns with a yellow flame Suppose: (a) it burns with yellow flame (T may be true or false) (b) it burns with a blue flame (T is false)

Falsificationism (1) Scientific method: Scientific theories have deductive consequences • They can be falsified but not confirmed. • The objective of scientific theorizing is to put forward (bold) hypotheses and then test them in order to falsify them • Theories are falsified by basic statements (what is a basic statement?)

Falsificationism (1) Demarcation: • Scientific theories are those that can be falsified by basic statements. • Good scientific theories do not make themselves immune from falsification by use of ad hoc hypotheses

Falsificationism (1) Progress of Science: • Science progresses by eliminating theories that have been falsified? • But does it progress? • A scientific theory cannot be shown to be true. But some scientific theories do have varying degrees of success. They resist falsification.

Falsificationism (1) Guidance for Scientists: Is there a rational criterion for choosing between competing theories?

Verisimilitude: We can compare competing theories according to their relative verisimilitude (truth likeness)

T1 has more verisimilitude than T2 or is equal to T2 iff: All the true consequences of T2 are contained in T1 and all the false consequences of T1 are contained in T2

Falsificationism (1) “We must not look upon science as a body of ‘knowledge’, but rather as a system of hypotheses which in principle cannot be justified, but with which we work as long as they stand up to tests, and of which we are never justified in saying that we know that they are ‘true’, or ‘more or less certain’ or even ‘probable’

Kuhn (1) Thomas Kuhn (1922-1996)

The Copernican Revolution (1957) The Structure of Scientific Revolutions (1962) • History of science not compatible with rationalist view • Progress of science not cumulative, driven by the application of a method

Kuhn (1) Thomas Kuhn (1922-1996)

The Copernican Revolution (1957) The Structure of Scientific Revolutions (1962) • No obvious science/non-science demarcation • No context of discovery/context of justification distinction

Kuhn (1) Kuhn’s History of Science Two projects: •

Descriptive — what is the structure of scientific history? Normal science Scientific revolution

•

Explanatory — why does the history of science have this structure? Paradigms

Kuhn (1) 1. Kuhn’s History of Science Descriptive Project: Immature Science Revolution Normal Science Crisis Anomalies

Paradigm Diagram old paradigm

unexplained observations in c o

mm

ens

u rat

competing new paradigms

e

puzzle solving

one dominant paradigm Mopping up operation

unsolved puzzles ignored unexplained observations and alternative interpretation ignored until enough accumulates to overturn current paradigm

unexplained observations

Kuhn (1) 1. Kuhn’s History of Science Immature Science: No prevailing school of thought Various disparate theories Competition

Kuhn (1) 1. Kuhn’s History of Science Normal Science: •

Stability

•

Determination of significant facts

•

Matching facts with theories

•

Articulation of theories (refinement and extension)

“puzzle -solving” neither tests nor confirms its theories

Kuhn (1) 1. Kuhn’s History of Science Normal Science: • Driven by a paradigm (more later): • Commonly held set of beliefs, procedures, techniques • Agreement upon questions of import • Agreement on what counts as a solution • Agreement upon standards of evaluation

Kuhn (1) 1. Kuhn’s History of Science Anomalies: Not all expectations are borne out • Some anomalies lead to further discoveries (e.g. orbit of Uranus) • Some simply ignored • Troublesome anomalies Challenge key theoretical concepts Resist solutions Inhibit application of theory

Kuhn (1) 1. Kuhn’s History of Science Crisis: • Weight of accumulated anomalies • No agreement on how anomalies are to be dealt with • Doubts arise

Kuhn (1) 1. Kuhn’s History of Science Revolution: A new paradigm emerges Old Theory: well established, many followers, politically powerful, well understood, many anomalies New Theory: few followers, untested, new concepts/techniques, accounts for anomalies, asks new questions

Kuhn (1) 1. Kuhn’s History of Science Revolution: A new paradigm emerges Are old and new theories compared by some rational procedure? “A new scientific theory 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” (Planck)

Kuhn (1) Scientific Revolutions The Ptolemaic model The earth is at the centre of the planetary system Problem: How to explain the retrograde motion of planets

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Kuhn (1) Scientific Revolutions The Ptolemaic model

The earth is at the centre of the planetary system Problem: How to explain the retrograde motion of planets

Deferent Earth

Planet

Epicycle

Kuhn (1) Scientific Revolutions The Ptolemaic model

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The earth is at the centre of the planetary system

Kuhn (1) Scientific Revolutions The Ptolemaic Model: Problems: •

Complexity: epicycle upon epicycle

•

The accumulation of anomalies

•

No clear way forward

Kuhn (1) Scientific Revolutions The Copernican model The sun is at the centre of the planetary system Problem: How to explain the retrograde motion of planets

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Kuhn (1) Scientific Revolutions The Copernican model

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The sun is at the centre of the solar system

Kuhn (1) Scientific revolutions The Copernican Model: Problems: (i) The rotation of the earth

? A

A

B

B

Kuhn (1) Scientific Revolutions The Copernican Revolution was not the consequence of an old theory with less ‘empirical content’ being replaced by a new theory with more •

No appeal to reason alone

•

‘propaganda’ To discover how scientific revolutions are effected, we shall therefore have to examine … the techniques of persuasive argumentation within the quite special groups that constitute the community of scientists (SSR: 94)

Kuhn (1) 2. Explanatory Project Two Questions: (i) If this is the course of the history of science, why? (ii) Why aren’t competing theories/traditions measured against each other by some rational procedure?

Kuhn (1) 2. Explanatory Project

Paradigms Two concepts: Sociological —a consensus, a body of beliefs shared among scientists working within a tradition: Disciplinary Matrix Individual — an example, prototype, teaching procedure: Exemplar

Kuhn (1) 2. Explanatory Project

Paradigms Disciplinary Matrix: (i) Symbolic generalisations (ii) Metaphysical commitments (iii) Scientific values (iv) Heuristic models (v) Exemplars

Kuhn (1) 2. Explanatory Project

Paradigms Exemplars: Not explicit rules Illustrations of theories, text book examples, critical experiments. Those things that are used to induct a new scientist into the practice of the disciplinary matrix.

Kuhn (1) 2. Explanatory Project

Paradigms Exemplars: The roles of an exemplar: • Semantic • Identify puzzles • Suggest procedures • Demarcate adequate solutions • Determine relevant questions

Kuhn (1) 2. Explanatory Project Why is normal science stable? It is conducted wholly within the terms of a disciplinary matrix: questions procedures problems priorities standards of evaluation All are generated by the disciplinary matrix

Kuhn (1) 2. Explanatory Project Why is theory change revolutionary? Theory change is brought about by a ‘gestalt switch’ a complete change of world view

There is no neutral point from which one can assess theories from two paradigms simultaneously

Kuhn (1) Kuhn sources on the web General: http://webpages.shepherd.edu/maustin/kuhn/kuhn.htm

http://philosophy.wisc.edu/forster/220/kuhn.htm

Thomas Kuhn (1922-1996) • All research presupposes a world-view,a collection of fundamental objects, natural laws, definitions, and above all a definition of what research is. • Kuhn called a world-view, paradigms • Mature science have established paradigms • Example of mature sciences are chemistry, physics, geology; whereas, economics and psychology are immature sciences.

Paradigm • Thomas Kuhn popularized the term in his book The Structure of Scientific Revolutions (1996) by using it to describe how science works. According to Kuhn, scientific explanations of the world are controlled by a paradigm, some model of how the world is expected to work and into which actual observations are fitted, even if the fit is not very exact. As inexact fits accumulate, it becomes more apparent that the dominant paradigm is inadequate as a model of reality. When enough contradictions exist, a paradigm revolution occurs and a new paradigm is adopted. • The word paradigm comes from the Greek paradeiknunai and means "to compare." In science and philosophy it has the same basic meaning as in common usage: a model or instance used as a basis or example for further work.

Need for Paradigms • Research requires paradigms • Paradigms are models of the way the world works • Without paradigms research is a random collection of observations lacking unification of structure into a whole. • Without paradigms, it is not possible to decide which are and which are not important observations

Dominant Paradigms

As a field matures, one paradigm becomes the dominant one. Once paradigms is established research progresses quickly

Paradigm guides direction of Research It becomes clear with aid of paradigm which research areas are fruitful. These areas are ones not totally explained Paradigms give concepts and laws to build on.

Paradigm Shift Paradigm shift occurs when old paradigm shown inadequate What is defined as research is reevaluated Concepts turn upside down. Earlier research is reinterpreted

Real research • Real Research occurs during a paradigm shift • Once a paradigm dominates, research becomes puzzle solving • Puzzle solving is not research due to answers known beforehand

Example of Puzzle Solving After Newton explained solar system, later scientists using Newton’s theory predicted The presence of the then unknown planets Neptune, Uranus, and Pluto

What New Paradigms Do • Discovery of new paradigm results in new questions being asked and old questions abandoned • Newton saw gravitation as a property of matter. Earlier theories tried to find a mechanical explanation as whirlpools in space or angels.

Paradigms are Incommensurable • Paradigms have different world view. It is difficult to compare them • Consequently, science defines truth relative to a paradigm and not absolutely. Truth is a story

Science • Science is a conformist society which present only the currently accepted theory Consequently science defines reality relative to the accepted paradigm • Students are educated into the accepted paradigm and to ignore alternative paradigms • The society of science determines what scientists observe

Imre Lakatos (1922 - 1974) `

• All scientific theories are equally un-provable • Falsification doesn’t work due to rescue hypotheses • the "basic unit" of scientific development is not the scientific theory, such that science progresses when one theory proves to be more successful than another.

Imre Lakatos the "basic unit" is actually the research program. Science progresses when one research program becomes more productive and more useful than other and, hence, receives a greater share of social resources through funding and younger scientists looking to join. A research program is characterized by a particular set of "hard core" fundamental ideas and is deemed successful so long as it contents continue to increase.

Imre Lakatos •

In reality scientists do not abandon theories. They invent rescue hypotheses or ignore anomalies or refutations

•

Popperian crucial experiments and Kuhnian revolutions turn out to be myths. What happens is progressive research replaces degenerating ones.

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Progressive scientific programs predict and produce dramatic, unexpected observations and results

Falsificationism Popper Science progresses toward its goal of increasing verisimilitude by advancing bold conjectures and then attempting to refute these by observations •

Theories cannot be verified by observation —anti-inductivism —no theory/observation distinction

•

Theories are falsified by basic statements

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We choose between theories on grounds of corroboration (mark of verisimilitude)

Scientific Research Programmes Imre Lakatos (1922-1974) Objective is to maintain Popperian insights: • Goal of Science: Increasing verisimilitude • Method of Science: Rational account of the assessment of theories • Forge a link between the goal of science and its methods

Scientific Research Programmes Revision versus Ad hoc Hypotheses Duhem-Quine Thesis: ‘Theories face the tribunal of experience as corporate entities’ (Quine) What gets tested against experience: • Theory • Auxiliary assumptions • Initial conditions • ‘Basic statements’

Scientific Research Programmes Revision versus Ad hoc Hypotheses Duhem-Quine Thesis: A theory as a web of belief • Touches experience at the periphery • More central parts more removed from direct evaluation by experience (e.g. principles of logic) One can make a change anywhere in the web Any theory can be made consonant with any set of observations (Underdetermination)

Scientific Research Programmes Revision versus Ad hoc Hypotheses Two questions In the light of anomalies: (i) What should one change? Principle of least change (ii) When should one abandon a theory(in favour of another)?

Scientific Research Programmes Scientific Research Programmes (SRP) A theory is: • Rules of logic and mathematics • Metaphysical commitments • Statements of laws • Assumptions about initial conditions A SRP is a lineage of theories. SRP evolve over time Rules according to which SRP’s evolve over time.

Scientific Research Programmes Scientific Research Programmes (SRP) Parts of a SRP:

Hard Core: Theoretical assertions Metaphysical commitments

HC AB

Auxiliary Belt: Initial conditions Assumptions Ad hoc hypotheses

Scientific Research Programmes Scientific Research Programmes (SRP) Parts of a SRP:

e.g. Celestial Mechanics

HC

Hard Core: Laws of Motion Universal Gravitation Space and time

Auxiliary Belt: AB

Number of planets Masses of planets

Scientific Research Programmes Rules Governing Changes to SRP

Negative Heuristic: • ‘Don’t touch the hard core’ • Hard core is held true ‘by convention’; it is not up for falsification Positive Heuristic: • Set of rules concerning how to deal with anomalies, what to change

Scientific Research Programmes Assessing/Comparing SRP

Three Criteria for a Good SRP: (i) Later theories have excess empirical content: predicts novel outcomes (ii) Later theories explain the success of earlier theories (iii) Later theories have more corroboration When a SRP meets these conditions it is said to be progressing

Scientific Research Programmes Assessing/Comparing SRP

Three Criteria for a Good SRP: (i) Later theories have excess empirical content: predicts novel outcomes (ii) Later theories explain the success of earlier theories (iii) Later theories have more corroboration When a SRP fails to meet these conditions it is said to be degenerating Progressive SRP’s replace degenerating ones

Scientific Research Programmes Content of the Positive Heuristic Two Readings: (i) Strong reading: heuristic contains explicit rules for dealing with each anomaly in a given SRP. (ii) Weak reading: heuristic contains general injunctions (e.g. ‘seek unified theories’, ‘quantitative theories are better than qualitative ones’)

Scientific Research Programmes Content of the Positive Heuristic Should yield a method for revising theories, guiding research and assessing SRP’s. “…defines problems, outlines the construction of a belt of auxiliary hypotheses, foresees anomalies and turns them victoriously into examples, all according to a preconceived plan.” “… a partially articulated set of suggestions, or hints, on how to change, develop…the ‘refutable’ protective belt’ (Lakatos TMSRP)

Scientific Research Programmes Problems with SRP 1.

Positive Heuristic: (i) Strong Reading: what could count as a set of general rules for dealing with all conceivable anomalies? (ii) Weak reading: No big deal. Positive heuristic held in common between all SRP’s. Insufficient to offer a criterion of choice between competing SRP’s

Scientific Research Programmes Problems with SRP 2. Assessing Theories: (i) Hard Cores held true as convention The success of a SRP, then, may simply be down to the success of the positive heuristic. Incompatible with Lakatos’ realism. Why don’t we view theories as simply instrumental devices?

Scientific Research Programmes Problems with SRP 2. Assessing Theories: (ii) Hard Cores actually do get tested Apparent location

Actual location

moon

Scientific Research Programmes Problems with SRP 2.

Assessing Theories:

(ii)i Hard Cores actually do get tested • Metaphysics of space/time • Laws of gravitation • Behaviour of light in gravitational field

Scientific Research Programmes Problems with SRP 3.

Comparing SRP’s:

(i) Assessing relative empirical content (Popper) (ii) SRP’s wax and wane (iii) Why is the success of SRP a sign of verisimilitude? (iv) What is the reason for thinking that the method of science is a means to its goal

Questions for tests or Class Discussion* •What kind of activity is science? •Is Basketball a science? •Is boxing a science? •Differentiate between natural philosophy and natural history. •Where was science first practiced and by whom? •See sections 2.1,2.3,3.1,3.24,5,6,&7 Theory7Reality”.Godfrey-Smith, Chicago Press,2003

Paul Feyerabend • In his books Against Method and Science in a Free Society Feyerabend defended the idea that there are no methodological rules which are always used by scientists.

Feyerabend's position •

is generally seen as radical in the philosophy of science, because it implies that philosophy can neither succeed in providing a general description of science, nor in devising a method for differentiating products of science from non-scientific entities like myths. It also implies that philosophical guidelines should be ignored by scientists, if they are to aim for progress.

Feyerabend & Falsification • Feyerabend was also critical of falsificationism. He argued that no interesting theory is ever consistent with all the relevant facts

Feyerabend & Consistency •

One of the criteria for evaluating scientific theories that Feyerabend attacks is the consistency criterion. He points out that to insist that new theories be consistent with old theories gives an unreasonable advantage to the older theory. He makes the logical point that being compatible with a defunct older theory does not increase the validity or truth of a new theory over an alternative covering the same content. That is, if one had to choose between two theories of equal explanatory power, to choose the one that is compatible with an older, falsified theory is to make an aesthetic, rather than a rational choice. The familiarity of such a theory might also make it more appealing to scientists, since they will not have to disregard as many cherished prejudices. Hence, that theory can be said to have "an unfair advantage".

Questions for tests or Class Discussion • Define epistemology. • Define metaphysics • Explain the correspondence between the visible and non-visible worlds. • Is there a scientific method? If so list the • Components of the method. • What is empiricism?

Questions for tests or Class Discussion • Discuss the social structure of science. • What was Locke’s theory of the mind? • How does Hume’s theory of mind differ from that of Locke? • Explain “external world skepticism. • Explain “inductive skepticism.

Questions for tests or Class Discussion • What is rationalism? • What is the analytic/synthetic distinction made with in Logical Empiricism? • Write a essay about the following: • “If a sentence has no possible method of verification, it has no meaning”.

Questions for tests or Class Discussion • Give an example where a nonobservable explicates an observable. • What does it mean to say a theory can never be proved? • Discuss “holism” in relation to testing an hypothesis.

Questions for tests or Class Discussion •What philosopher espoused the idea of epistemological anarchy? •What is meant by theory laden observations? •Are religion and science incommensurate majesteria?

Questions for tests or Class Discussion •Distinguish between science and pseudoscience. •What is the problem of demarcation and how does Popper address it? •What according to Popper defines a scientific hypothesis?

Questions for tests or Class Discussion •Discuss Popper’s contention that it’s never possible to confirm an hypothesis. •Why is inductive skepticism no threat to the rationality of science? •What are the two steps Popper claims in which scientific change occurs?

Questions for tests or Class Discussion • What is a paradigm? • How does a revolution occur in science? • What is normal science? • Is normal science open to new ideas? Elucidate. • What is according to Lakatos a research program?

Basic Questions Are these questions logically equivalent?

Do you believe in God? Do you believe in Science? Do you believe God? Do you believe Science

Definitions know:to perceive directly, to recognize, to be the same certain: fixed, settled, reliable, true truth: fidelity, constancy, fact fact: a thing done, actual, objective reality evidence(to see from Latin):furnishing proof proof:cogency of evidence that compels acceptance validity:justified, correctly derived from premises

Three Theories of Truth Coherence-theory true if it “coheres” or is consistent with other statements.

Pragmatic-It’s true if it works. Semantic- language deceives us by setting up relationships

Science and religion Is science different from religion in that both are not faith based? Does science’s request for evidence no matter how tenuous the evidence “coheres” to the hypothesis making science different from religion?

Falsificationism Problems for Falsificationism (recap) Falsification: Some legitimate features of scientific enterprise are not falsifiable: •

Probabilistic Statements

•

Existential Statements

•

Metaphysical Commitments

Falsificationism (finale) Problems for Falsificationism Verisimilitude: We judge a theory’s verisimilitude by its degree of corroboration. How could corroboration be a criterion of verisimilitude? The past performance of a theory can be taken as evidence of its verisimilitude only if one is willing to make inductive inference on the past successes of a theory

Falsificationism (finale) Problems for Falsificationism (recap) Verisimilitude: We judge a theory’s verisimilitude by its degree of corroboration. Why should a theory be chosen on the grounds of true consequences alone.

e.g. Ptolemaic versus Copernican systems Ptolemaic system had larger number of true consequences. Copernican system simpler

Falsificationism (finale) Problems for Falsificationism (recap) 2. Verisimilitude: We judge a theory’s verisimilitude by its degree of corroboration. Why should a theory be chosen on the grounds of true consequences alone. Other virtues: simplicity productivity unification

Falsificationism (finale) Problems for Falsificationism 3. Basic Statements: Theories are falsified by basic statements. What warrants our acceptance of basic statements? (i) Observation?: No. Basic statements are theory laden. Accepting them requires accepting theory (ii) Decision/convention: not grounded in a rational procedure

Falsificationism (finale) ‘Whiff of Inductivism’ “… there may be a whiff of inductivism here. It enters with the vague realist assumption that reality, though unknown, is in some respects similar to what science tells us or, in other words, with the assumption that science can progress towards greater verisimilitude” (1974)

Falsificationism (finale) ‘Whiff of Inductivism’ Two inductive claims: 1: ‘vague realist assumption’: theories increase in their verisimilitude 2. Theories that have performed well in the past have a greater degree of verisimilitude

Falsificationism (finale) ‘Whiff of Inductivism’ A Dilemma for Popper: (i)

Give up on induction —No rational criterion for choosing between competing theories —No rational grounds for continuing to use successful theories

(ii) Give up the distinctive features of falsificationism

Falsificationism (finale) Problems for Falsificationism 3. Basic Statements: Theories are falsified by basic statements. What warrants our acceptance of basic statements? (i) Observation?: No. Basic statements are theory laden. Accepting them requires accepting theory (ii) Decision/convention: not grounded in a rational procedure

Falsificationism (finale) ‘Whiff of Inductivism’ “… there may be a whiff of inductivism here. It enters with the vague realist assumption that reality, though unknown, is in some respects similar to what science tells us or, in other words, with the assumption that science can progress towards greater verisimilitude” (1974)

Falsificationism (finale) ‘Whiff of Inductivism’ Two inductive claims: 1: ‘vague realist assumption’: theories increase in their verisimilitude 2. Theories that have performed well in the past have a greater degree of verisimilitude