lecture 31 scientific progress and its problems verification, falsification or what?

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Scientific Progress and Its Problems

Verification, Falsification or What?

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Introduction

The aim of the lecture is To present the major conceptions of

scientific growth To discuss their respective strong and

weak points.

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Main Topics

The inductivist model of science Karl Popper’s falsificationism Thomas Kuhn’s structural criterion of

science Imre Lakatos, sophisticated

falsificationism, and research programmes

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Main Topics

The abandonment of the search for ‘the’ method (Feyerabend)

Larry Laudan’s research traditions How to judge the value of a scientific

theory?

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The Inductivist Model of Science (1)

The facts are observed and recorded. The observed and recorded facts are

analysed, compared and categorized.

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The Inductivist Model of Science (2)

From this analysis of the facts, generalizations are inductively drawn as to the relations (empirical regularities) between them.

Further research is inductive as well as deductive, employing inferences from previously established generalizations.

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Figure 1: the Inductivist Model

Facts acquired through observation

Predictions and explanations

Laws and theories

Induction Deduction

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Popper’s Falsificationism (1)

Not verification, but falsification Reason: the classical problem of induction

Observation is always affected by prior theoretical and conceptual commitments: it is guided by and presupposes theory (the so-

called searchlight theory of knowledge) observation is thus theory-laden

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Popper’s Falisficationism (2)

Theories cannot be established as true in the light of observational evidence.

Theories are constructed as speculative and tentative conjectures freely created by the human intellect in an attempt to overcome problems encountered by previous theories to give an adequate account of some aspects of the world. That is why Popper’s epistemology is commonly

labelled ‘critical rationalism’.

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Once proposed, speculative theories are to be rigorously and ruthlessly tested by observation and experiment

Theories that conflict with empirical evidence must be eliminated (falsified) and replaced by new theories

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Science thus progresses by trial and error, by conjectures and refutations

Only the fittest theories survive and are tentatively and temporarily accepted

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A theory can never be said to be true Of a theory it can only be said that it is

the best available in the sense that is better than anything that has come before – at least for the time being.

As a consequence there is no certainty in science scientific knowledge is always tentative.

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Kuhn’s Structural Criterion of Science (1)

Scientists do not in fact falsify theories in the ‘instant’ way specified by Popper

While at the level of empirical hypotheses Popperian falsificationism may operate, this cannot be maintained at the level of broader theoretical structures or the evolution of science as a whole

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According to Kuhn scientific evolution should be understood as the development of complex structures of theories or, as he calls them, ‘paradigms’

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The central concept of Kuhn’s epistemology is ‘paradigm’.

Masterman identifies three basic concepts within Kuhn’s notion of paradigm: the ‘metaphysical’ paradigm, the ‘sociological’ paradigm, and. the ‘artefact’ paradigm.

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The metaphysical paradigm involves the ontological elements of a theory, namely those assumptions that affect the way in which man views the world and his place in it.

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The sociological paradigm refers to a concrete scientific achievement that functions as a model or framework within which scientific research is conducted.

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Thomas Kuhn’s Structural Criterion of Science (6)

Finally, the artefact paradigm concerns a distinct set of tools, techniques or instrumentation that are considered relevant to he validation of scientific knowledge.

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Normal science Crisis Revolutionary science ‘Gestalt’ switch New period of normal science

New paradigm is incommensurable with previous one

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A paradigm will never be replaced unless a ‘less problematic or better’ one comes around

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Within this general process of development of science Kuhn stresses: the importance of the scientific

community the role of extra-scientific elements

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This implies a conception of science as a social activity

Epistemology is an empirical science

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Lakatos, Sophisticated Falsificationism, and Research Programmes (1)

Naïve falsificationism A theory is falsified by an

observational statement that conflicts with it

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Sophisticated falsificationism A theory T1 is falsified if another theory T2

has been proposed with the following characteristics: T2 has excess empirical content over T1: that is, if

it predicts novel facts T2 explains the empirical content of T1 Some of the excess content of T2 is corroborated

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Research programmes Theories are part of broader structures,

which Lakatos calls “research programmes”

Within such a programme theories develop in a dynamic way

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A theory that is shown to be inadequate is replaced by a better one but typically one which belongs to the same family We have a sequence of theories, T(1),

T(2), T(3) and so on, each of which explains more than its predecessor and thus supersedes it

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Such a sequence of interrelated theories is what Lakatos calls a scientific research programme

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The family relationship is carried on by the negative heuristic or hard core, which will not be doubted, at least during the course of the programme.

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Whenever observations do not fit smoothly into this framework and objections are raised the rational response is

not to forego the hard-core assumptions but to protect them by a set of auxiliary

hypotheses that aim at increasing the predictive power of the

programme and in this way ‘protect’ the hard core

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The part of the research programme containing the auxiliary hypotheses is thus called the protective belt or positive heuristic It indicates what needs to be done in

order to increase the explanatory and predictive power of the programme.

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When is a research programme falsified? A research programme R1 is falsified

when there is an alternative research programme R2 that1. can explain and predict as much as

research programme R1 does

2. predicts novel facts, some of which are corroborated

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Feyerabend: the Abandonment for the

Search of ‘The’ Method

Feyerabend’s key points are: All methods have their limitations ‘The’ method of science does not exist Therefore, the most reasonable position

is that of methodological pluralism The importance of creativity in science:

anything goes

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Laudan’s Research Traditions (1)

Laudan argues that Lakatos’ criteria for falsifying research programmes, namely theoretical and empirical progressiveness, are too strict and do not stand the test of the history of science.

In essence his position boils down to a pragmatic interpretation and integration of Kuhnian and Lakatosian concepts.

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A research tradition is a set of general assumptions about the entities and the processes in a domain

of study (ontology), and about the appropriate principles and

methods to be used for investigating the problems and constructing the theories in that domain (epistemology and methodology).

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Contrary to Lakatos these general assumptions (hard core assumptions if you wish) may change

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Laudan’s Research Traditions (4): Empirical and Conceptual Problems

For Laudan science is not only about empirical problems but also about conceptual problems

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Laudan’s Research Traditions (5): Nature of Empirical Problems

Empirical problems are problems about the world

Empirical problems are theory-laden as they are generated within a certain theoretical structure

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Laudan’s Research Traditions (6): Nature of Empirical Problems

He distinguishes three kind of empirical problems: solved problems unsolved problems anomalous problems

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Laudan’s Research Traditions (7): Nature of Conceptual Problems

Internal conceptual problems: when T exhibits certain internal inconsistencies, or when its basic categories of analysis are vague and unclear

External conceptual problems: when T is in conflict with another theory, T’, which proponents of T rationally believe to be well founded

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Laudan’s Research Traditions (8): Sources of Conceptual Problems

Intra-scientific difficulties Normative difficulties Worldview (ontological) difficulties

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Laudan’s Research Traditions (9): Core Assumptions

The solved problem – empirical or conceptual – is the base of scientific progress (pragmatism)

The aim of science is to maximise the scope of solved empirical problems, while minimising the scope of anomalous and conceptual problems

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Laudan’s Research Traditions (10): Evaluation of Theories

The first and essential test for any theory is whether it provides acceptable answers to

interesting questions: whether, in other words, it provides satisfactory

solutions to important problems

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Larry Laudan’s Research Traditions (11): Evaluation of Theories

In appraising the merits of theories, it is more important to ask whether they constitute adequate solutions to

significant problems than it is to ask whether they are “true”,

“corroborated”, “well confirmed” or otherwise justifiable within the framework of contemporary epistemology

This is a kind of judgemental rationalism (Bhaskar)

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Larry Laudan’s Research Traditions (11): Evaluation of Theories

The overall effectiveness of a theory is determined by

assessing the number and importance of the empirical problems, which the theory solves, and

deducting thereof the number and importance of the anomalies and conceptual problems, which the theory generates, determine the overall effectiveness of a theory

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How to Judge the Value of a Scientific Theory or Model? A Few Rules of Thumb

To which degree does it tackle the problems for which it was designed, compared to others that are applicable to the same problems?

To what extent can one relax its assumptions and still retain a coherent model?

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To which extent events that do not conform to the model’s predictions can be explained by a manageable examination of its conditions?

To which extent it is able to generate propositions about the real world that are not attainable through simple observation and common sense?

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To which extent does it lead to the construction of a new and better model?

lecture 31 scientific progress and its problems verification, falsification or what?

Documents

inductivist model slide

theoryladen slide

evolution of science

poppers falisficationism

scientific theory

science scientific knowledge

speculative theories

previous theories