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Mechanisms and systems: Mechanisms and systems: causal issues in the social sciencescausal issues in the social sciences

Federica RussoPhilosophy, Louvain & Kent

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OverviewCausal modelling

MethodologyPresuppositions

System analysisPresuppositionsMethodology

Causal modelling vs. Systemics

A case studyHealth systems and mortality

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Causal modellingGoals

Detecting causes of effectsMeasuring effects of causesUncovering causal structuresModelling causal mechanisms…

MethodsQualitative/QuantitativeAggregate/Individual/Multilevel…

MethodologyHypothetico-deductivism

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Causal models are made ofAssumptions

StatisticalExtra-statisticalCausal

Key notionsBackground knowledgeExogeneityInvariance/StabilityClosure of the system

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Causal assumptions

Covariate sufficiencyAll the variables included in the modelare needed to explain the phenomenon

No-confoundingNo variable included in the modelscreens-off other variables

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Working hypothesis: the system is closed

Strict closureThe system described is not subject to any external influence

X Y

R V

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Working hypothesis: the system is closed

Weak closureVariables in the model undergo influencesfrom non-observed variables non correlatedbetween themselves

X Y

R VI1 I2

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Working hypothesis: the system is closed

Failure of closureVariables in the model undergo influencesfrom non-observed variables that arecorrelated between themselves

X Y

R V

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Causal models model mechanisms

Mechanisms are a scheme ofhow variables relate to each other

Variables play specific (causal) roles

Some types of relations are excluded,e.g. loops

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Hypothetico-deductivismHypothesise stage and prior information

Causal hypotheses are (dis)confirmeddepending on results of tests andon congruence with background knowledge

A dynamic processVa et vient between established theoriesand establishing theories

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System analysis: scope and goals

System theoristsvon Bertalanffy (1969), Bunge (1979)

A general theory of systemsin the various sciences

Formulation and derivation ofprinciples valid for all systems

Systems are ubiquitous,a general framework is needed

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von Bertalanffy:Major aims of a general system theory (1969):

1. there is a general tendency towards the integrationin the various sciences, natural and social;

2. such integration seems to be centredin a general system theory;

3. such theory may be an important means of aimingat exact theory in the non-physical fields of science;

4. developing unifying principles running ‘vertically’through the universe of the individual sciences;

5. this can lead to a much-needed integrationin scientific education.

General system theory aims toencompass various disciplines.

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What is a system?A system is a set of elements standingin reciprocal interrelations

Elements, p, stand in relation, R, so that the behaviour of an element p in R is different from its behaviour in another relation, R’. If the behaviours in R and R’ are not different, there is no interaction, and the elements behave independently with respect to the relations R and R’.(von Bertalanffy 1969, p.37)

Systems are mathematically definedby certain families of differential equationsSystems are not aggregates

(= collections of items not held togetherby bonds and lacking integrity)

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Systems and the wholeScience of the whole

Holism:stresses integrity of systems at the expenses oftheir components and of mutual actions among themAtomism:the whole is contained in its parts, so the studyof parts suffices to understand the whole

Neither can properly analyse systems

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Systemics methodology (Bunge)

Firstidentification of the components of the system

Secondidentification of the environment

Thirdidentification of the structure

N.B.: no prior hypotheses about the structure

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Systemics, a different worldview

von Bertalanffy:systemics open a new paradigm

System philosophyAgainst the analytic, mechanistic,one-way causal paradigm of classical science

No sharp difference betweenthe object of investigation and the knowing

agent

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A different worldviewvon Bertalanffy (1969)

Perception is not a reflection of ‘real things’ (whatever their metaphysical status), and knowledge is not a simple approximation to ‘truth’ or ‘reality’. It is an interaction between knower and known, this dependent on a multiplicity of factors of a biological, psychological, cultural, linguistic, etc., nature.

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A different worldviewVon Bertalanffy (1969)

The third part of systems philosophy will be concerned with the relations of man and world or what is termed ‘values’ in philosophical parlance. If reality is a hierarchy of organized wholes, the image of man will be different from what it is in a world of physical particles governed by chance events as ultimate and only ‘true’ reality. Rather, the world of symbols, values, social entities and cultures is something very ‘real’; and its embeddedness in a cosmic order of hierarchies is apt to bridge the opposition of C.P. Snow’s ‘Two Cultures’ of science and the humanities, technologies and history, natural and social sciences, or in whatever way the antithesis is formulated.

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A different worldviewBunge (1979):

There are no stray things

Every thing interacts with everything elseso that all things cohere in forming systems

Every concrete thing is either a systemor a component of it

Every system is engaged in some process or other

Every change in a system is lawful

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Causal modelling vsvs. system analysis

Closure of the systemand mechanisms

The agent is external

Causal mechanisms are

established usingprior information

Every thing interactswith everything else

The agent is internal

Structures are identified

without prior information

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Causal analysis withinwithin system analysis?

Lauriaux (1994)theoretical weaknesses of causal analysis:

choice of variables, conceptualisation,closure of the system

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A case study:health system and mortality

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X1Economic

development

X2Social

development

X3Sanitary

infrastructures

X4Use of sanitary infrastructures

X5Age structure

YMortality

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Lauriaux’s critiquePrincipal variables are theoretical constructsaccording to well established economicand sociological theories

Assumption: economic developmentgenerates social development

Problem: counterexamples exist, the arrowmight be reversed with serious problems for policy

To intervene on an effect which is not an effectwon’t deliver the planned results

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Causal analysis withinwithin system analysis?

The problem still remains:How to make sense of covariationsbetween variables if we abandonthe causal framework?

Solution: system analysis

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ComplementarityComplementarityof the two approaches?

Systems are homeostatic:they keep themselves in a stable state by meansof regulatory interdependent mechanisms

Changes in the system re-establish theequilibrium in consequence of too stronginternal/external influences

In the process of balancing,components jointly evolve

Those joint evolutions are covariationswe call causal

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Lauriaux’s systemic story

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My systemic worriesSystems become very easily

intractable,of difficult use for policy

I haven’t seen precise,concrete methods to analyse data

Assumptions clash too much to makethe approaches complementary

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To sum upI sketched the features

Of causal modelling: closure of the system, use of prior information, mechanism

Of system analysis: different worldview, reciprocal interrelations of elements

I discussed the possibility of acomplementarity of the two approaches

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A charitable interpretation?

A weak notion of ‘system’Mechanisms are within (social) systemsRelax postulate that every thing interacts

with everything else

A weak and diversified notion of ‘interaction’The agent interacts with the system: she

interprets but doesn’t modify itThings can have correlational, causal, …,

interactions

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To concludeAre those approaches compatible?

I think not, because of significantlydifferent assumptions

Is systemics a viable alternative?I think not, because clear methodsare still lacking

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Unless …A charitable interpretation ofsystems and interaction is provided

Peculiar import of systemicsis perhaps distort

Yet causal modelling gains … ?

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References Bunge M. (1979). A world of systems. Reidel Publishing Company.Franck R. (1994) (ed). Faut-il chercher aux causes une raison? Vrin.Franck R. (2002) (ed). The Explanatory Power of Models. Springer.Lauriaux M. (1994),  “Des causes aux systèmes: la causalité en question”,

in Franck (1994).Lopez-Rios O., Mompart A. and Wunsch G. (1992). Système de soins et

mortalité régionale: une analyse causale, European Journal of Population, 8(4), 363-379.

Pumain D. (2006) (ed). Hierarchy in natural and social sciences. Springer.Russo F. (forthcoming), Measuring variations. Causality and causal

modelling in the social sciences. Springer.von Bertalanffy (1969), General system theory. Braziller.