1. Lars-Erik Cederman and Luc Girardin Center for Comparative and International Studies (CIS) Swiss Federal Institute of Technology Zurich (ETH) http://www.icr.ethz.ch/teaching/compmodels Advanced Computational Modeling of Social Systems

2. 2 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)

3. 3 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

4. 4 Outline Computational Modeling Sociological Process Theory Epistemology Ontology Nomothetic theory Generative theory Nomothetic modeling Generative modeling Variable-based theory Configurative theory Variable-based modeling Agent-based modeling

5. 5 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

6. 6 The epistemology of process theory Compuational Modeling Sociological Process Theory Epistemology Ontology Nomothetic theory Generative theory Nomothetic modeling Generative modeling Variable-based theory Configurative theory Variable-based modeling Agent-based modeling

7. 7 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

8. 8 The ontology of process theory Computational Modeling Sociological Process Theory Epistemology Ontology Nomothetic theory Generative theory Nomothetic modeling Generative modeling Variable-based theory Configurative theory Variable-based modeling Agent-based modeling

9. 9 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

10. 10 The epistemology of computational modeling Computational Modeling Sociological Process Theory Epistemology Ontology Nomothetic theory Generative theory Nomothetic modeling Generative modeling Variable-based theory Configurative theory Variable-based modeling Agent-based modeling

11. 11 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.”

12. 12 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

13. 13 The ontology of computational modeling Computational Modeling Sociological Process Theory Epistemology Ontology Nomothetic theory Generative theory Nomothetic modeling Generative modeling Variable-based theory Configurative theory Variable-based modeling Agent-based modeling

14. 14 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.

15. 15 Modeling Emergence Four types of endogenous social forms: Behavioral interaction configurations Property configurations Interactive networks Actor structures

16. 16 Emergent interaction patterns actor Models of “emergent order” producing configurations Axelrod (1984, chap. 8): “The structure of cooperation”

17. 17 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 actor

18. 18 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-d-

19. 19 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?

20. 20 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.

21. 21 The Luhmann Simulator Prof. Dr. Uwe Schimank Fern Universität Hagen