empirical generalisations kent nov07
TRANSCRIPT
Empirical Generalisationsin Social Science
Federica RussoInstitut Supérieur de PhilosophieUniversité catholique de Louvain
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OverviewThe question:are there laws in social science?
Relevance of the questionHistoricallyIn the current debate
The consensus and the challenge
Empirical generalisationsin structural models
On invariance:Pandora’s box is open
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Relevance of the questionQuetelet (1869):society is regimented by lawsas much as Nature
Statistics is a science of the general,it establishes laws by analysing
regularities
The Average Man, i.e. the meanaround which social elements oscillate,is the basis of a social physics
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Quetelet’s reading showsThe goal of finding laws of society has fairly long
history
“Laws” in a strong sense, not just Humean regularities
HoweverQuetelet is liable to objections, e.g.:
Laws can’t be established by investigating regularities,but, if at all, by investigating variations
Statistics is not the study of the meanbut the study of the variance
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Relevance of the questionThe debate is still open
The social sciences cannot establish lawsbecause they are not as matureas the natural sciences
They are mature but there aren’tany laws to discover
There are laws, but we cannot know them
If there are laws, it is unclear whatkind of entities and mechanisms are involved
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Consider for instance:1) Roberts 2004
Laws are universal regularities
The special sciencesdo not have such laws
The absence of laws points toan essential difference betweenthe natural and social sciences
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Consider for instance:2) Kinkaid 2004
Some laws of physics do not establishuniversal generalisationsbut causal mechanisms
Such laws describe general tendencies,sometimes fragile
Many laws in social science are of this type
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Consider for instance:3) Woodward and Hitchcock 2003
Laws are empirical generalisations having
the characteristic of being invariant
Invariance gives themexplanatory and predictive power
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An implicit consensusIf there are laws, they don’t have the same
characteristics of the laws of physics
Whence the questionWhat are they?
AnswerEmpirical generalisations
A weaker concept
A different concept
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The challenge
To give an account ofempirical generalisations that is
Reasonable Meaningful Useful
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The strategyWhat is an empirical generalisation
in social science?
Goals of social science
Cognitive
Action-oriented
Role of causal knowledge
Structural modelling:
Establishing empirical generalisations
Their characteristics will depend on the conditiions of structural models
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Goals
CognitiveUnderstand/explainingsocial phenomena
Action-orientedInform/direct social policies
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Role of causal knowledgeCognitive aspect
Beyond description,to provide foundations for action
Action-oriented aspectIt presupposes intervening oncausal relationships/mechanisms
How to acquire suchcausal knowledge?
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Structural modelling,the quantitative approach
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X1Economic
development
X2Social
development
X3Sanitary
infrastructures
X4Use of
sanitary infrastructure
sX5
Age structure
YMortality
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XXY
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ElementsAssumptions
StatisticalExtra-statisticalCausal
MethodologyHypothetico-deductivism
Key notionsBackground knowledgeExogeneityInvariance
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In more detail:H-D methodology
1) formulate the hypothesis2) build the model3) confirm/disconfirm the hypothesis
Note:Not exactly Popperian H-DTerminological problems
H-D methodology makesstructural models flexible
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In more detail:background knowledge
General knowledge of thesocio-political context
Similar evidence of the same causalmechanism in other populations
Knowledge of thephysical-biological-physiological
mechanism
Use of similar/different methods and/or of data
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In more detail:exogeneity
An exogenous variable:“its” mechanism does not influencethe mechanism of interest
In a structural model,an exogenous variable isa causal variable
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4
13
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12
2
X1Economic
development
X2Social
development
X3Sanitary
infrastructures
X4Use of sanitary infrastructures
X5Age structure
YMortality
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In more detail:invariance
The traditional definition:Causality requires “invariance underintervention”, i.e. a relation has to beinvariant under a large class ofinterventions or environmental changes
The testinvariance require setting updifferent initial conditions
A counterfactual characterisation
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In more detail:invarianceWoodward & Hitchcock 2003:
A relationship R between variables X and Y is invariant if it would continue to be true (or approximately true) in at least some hypothetical situations or possible worlds in which the value of X is changed as the result of an intervention. That is, there must be some non-actual value x of X such that the following counterfactual is true: ‘if X were equal to x, then the values of X and Y would stand (approximately) in the relation R.’
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In more detail:invariance
Distinguish:Invariance concerning the variablesStructural stability concerning the model
Invariance is a property of observations,not of the model
The test:parameters have the same value or at leastthe same sign across sub-samples of the data
base
We get out of counterfactuals
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In more detail:structural stability
A model is structurally stable ifThe causal variables are exogenous
Relations among variables are invariant
Background knowledge backs upexogeneity, invariance and the structure
DistinguishInternal vs external stability
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Structural – what does it mean?
Looking for structures, mechanisms
A special case of thegeneral statistical model
An umbrella for different typesof causal models
Qualitative analysis is also structural
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That’s all to sayStructural models establishempirical generalisations
A causal claim that state an invariantrelation in structural model
Empirical generalisations causalSummary of statistics descriptive
Empirical generalisations allowexplanation – prediction – interventionbecause they are the result of a structural model
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Woodward’s invarianceGoal
Defend a theory of explanationand of explanatory generalisations
The claimEmpirical generalisations areexplanatory because invariant
The scopeExplanation in the special sciences,social and natural
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The divergenceWoodward’s central idea
Empirical generalisations show patterns of counterfactual dependence
Their explanatory power is due to their being able to answer WITHBD-questions
Counterfactuality is central toInvarianceExplanationCausal modelling
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Deeper and deeper divergences
Invariance-based approaches andin general counterfactual approaches
claim that they will establishcausal relations by evaluating
effects of interventions
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Pandora’s box is open
Woodward’s invariance presupposesan experimentalist approach
But what do we do in social sciencewith observational data?
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The counter-objection1) Interventions do not have an
anthropomorphic characterisationOK, fine
2) If we cannot intervene, we consider a hypothetical experiment
Pandora’s box is wide open
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In extremis rescue?Woodward 2003:
Instead, the role of [interventions] is to serve as a regulative idea: they tell us what must be true of the relationship between X and Y if X causes Y and in this way tell us what we should aim at establishing, perhaps on the basis of an imperfect or nonideal experiment, if we want to show that a causal claim is true.
But that’s exactly the problem!
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To sum upAre there laws in social science?
The question is relevant
We’d better look into theconcept of empirical generalisation
I’ve done that through ananalysis of structural modelling
The divergence with the “received views”opened a Pandora’s box
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Some remarksPartisans of counterfactual approachesoppose partisans of decision theory
Opposition is due to the weak foundationsof the counterfactual approach
Either we get rid of counterfactuals orwe provide them with better foundations
But mostly, counterfactuals do not sayhow to draw causal conclusionsfrom observational data