Lars-Erik Cederman and Luc GirardinCenter for Comparative and International Studies (CIS)

Swiss Federal Institute of Technology Zurich (ETH)http://www.icr.ethz.ch/teaching/compmodels

Advanced Computational Modelingof Social Systems

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Presentations

• 07.06.2005 III• 14.06.2005 III• 21.06.2005 III• 28.06.2005 II

• Nicolas Bürkler (4)• Thomas Fent • Stephan Gammeter

(2)• Jean-Luc Geering (1)• Jeremy Hackney (2)• Lutz Krebs (4)• Benjamin Lutz (1)• Charles Mitchell (3)• Gloria Müller (3)• Carsten Murawski (1)• Jonas Nart (3)• Nils Weidmann (2)

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Computational Models of Social Forms (AJS 2005)

• Putting agent-based modeling in a social-theoretic context:– Sociological process theory offers

theoretical guidance for future modeling– Computational modeling helps process

theorists craft better, more precise theories

• Focus on research problems at the macro-level

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Outline

ComputationalModeling

SociologicalProcess Theory

Epistemology

Ontology

Nomothetictheory

Generativetheory

Nomotheticmodeling

Generativemodeling

Variable-basedtheory

Configurativetheory

Variable-basedmodeling

Agent-basedmodeling

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Sociological process theory

• Simmel: sociations or Vergesellschaftung

• Chicago school: Mead et al• Elias’ “figurations”• Barth’s formal anthropology• Emirbayer’s “relationism”,

Giddens’ “structuration”, Archer’s “morphogenetic” approach, Fararo’s “generative theory”

Georg Simmel

George Herbert Mead

Norbert Elias

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The epistemology of process theory

CompuationalModeling

SociologicalProcess Theory

Epistemology

Ontology

Nomothetictheory

Generativetheory

Nomotheticmodeling

Generativemodeling

Variable-basedtheory

Configurativetheory

Variable-basedmodeling

Agent-basedmodeling

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Toward generative theory

• Covering laws ==> uncovering mechanisms

• Positivism ==> scientific realism• Abductive inference instead of

induction or deduction:– making the puzzling less puzzling– metaphors, analogies, and simple

models

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The ontology of process theory

ComputationalModeling

SociologicalProcess Theory

Epistemology

Ontology

Nomothetictheory

Generativetheory

Nomotheticmodeling

Generativemodeling

Variable-basedtheory

Configurativetheory

Variable-basedmodeling

Agent-basedmodeling

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Toward configurative theory

• A social form is a configuration of social interactions and actors together with the structures in which they are embedded.

• Variables merely measure dimensions of social forms, not the forms themselves.

• Social forms always have an extension in time and (geographic/abstract) space

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The epistemology of computational modeling

ComputationalModeling

SociologicalProcess Theory

Epistemology

Ontology

Nomothetictheory

Generativetheory

Nomotheticmodeling

Generativemodeling

Variable-basedtheory

Configurativetheory

Variable-basedmodeling

Agent-basedmodeling

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Toward generative modeling

• In Micromotives and Macrobehavior, Schelling invites the reader “to try to figure out what intentions, or modes of behavior, of separate individuals could lead to the pattern we observed.”

• Axelrod: “a third way of doing science”• Epstein: “If you didn’t grow it, you

didn’t explain it.”

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Emergence

• Can be exhibited by generative processes

• Emergent properties stem from the irreducibility of complex systems to the properties of their constituent parts

• Usually due to non-linear interactions among system components

• Bottom-up vs. intrinsic emergence

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The ontology of computational modeling

ComputationalModeling

SociologicalProcess Theory

Epistemology

Ontology

Nomothetictheory

Generativetheory

Nomotheticmodeling

Generativemodeling

Variable-basedtheory

Configurativetheory

Variable-basedmodeling

Agent-basedmodeling

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Toward agent-based modeling

• ABM features explicit representations of social forms.

• Whereas variable-based modeling expresses causal relations among variables, ABM represents interactions among the actors directly.

• Object-orientation facilitates the task of representing social forms.

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Modeling Emergence

Four types of endogenous social forms:• Behavioral interaction configurations• Property configurations• Interactive networks• Actor structures

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Emergent interaction patterns

actor actor actor

actor

actor

actor

actor

actor

actor

• Models of “emergent order” producing configurations

• Axelrod (1984, chap. 8): “The structure of cooperation”

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Emergent property configurations

• Models of “emergent structure” constituted as property configruations

• Example: Schelling’s segregation model; Carley 1991; Axelrod 1997

• See Macy & Willer 2002 for further references

actoractor

actoractor

actoractor

actoractor

actoractor

actoractor

actoractor

actoractor

actoractor

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Emergent networks

• Most computational models treat networks as exogenous

• Recent exceptions:– Albert and Barabási’s

scale-free networks– Economics and

evolutionary game theory: e.g. Skyrms and Pemantle

frequency

degree d

d-

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Emergent actors

• Computational models normally assume the actors to be given

• Some exceptions:– Axelrod’s model of new

political actors– Axtell’s firm-size model– Geopolitical models in

the Bremer & Mihalka tradition

• Emergence?

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Conclusions

• ABM follows in the epistemological and ontological footsteps of sociological process theory

• Future challenges of ABM: endogenization of networks and actor structures

• Future challenges of process theory: clearer specification of generative theory that allows for systematic empirical anchoring.

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The Luhmann Simulator

Prof. Dr. Uwe SchimankFern Universität Hagen