Generativism

There is a seductive appeal to the catch of a "generative social science". Joshua Epstein is ane of the principal proponents o...

There is a seductive appeal to the catch of a "generative social science". Joshua Epstein is ane of the principal proponents of the idea, most especially inward his book, link). The ABM is said to demonstrate the means inward which an observable social final result of pattern is generated past times the properties as well as activities of the ingredient parts that larn inward upward -- the actors. The appeal comes from the notion that it is possible to exhibit how complicated or complex outcomes are generated past times the properties of the components that brand them up. Fix the properties of the components, as well as you lot tin derive the properties of the composites. Here is Epstein's capsule summary of the approach:

The agent-based computational model -- or artificial gild -- is a novel scientific instrument. It tin powerfully advance a distinctive approach to social science, ane for which the term "generative" seems appropriate. I volition speak over this term to a greater extent than fully below, just inward a rigid form, the key catch is this: To the generativist, explaining the emergence of macroscopic societal regularities, such as norms or cost equilibria, requires that ane response the next question: 

The Generativist's Question 

*How could the decentralized local interactions of heterogeneous autonomous agents generate the given regularity?  

The agent-based computational model is well-suited to the written report of this question, since the next features are characteristic: [heterogeneity, autonomy, explicit space, local interactions, bounded rationality] (5-6)

And a few pages later:

Agent-based models render computational demonstrations that a given microspecification is inward fact sufficient to generate a macrostructure of interest. . . . To the generativist -- concerned alongside formation dynamics -- it does non suffice to constitute that, if deposited inward some macroconfiguration, the scheme volition remain there. Rather, the generativist wants an occupation organisation human relationship of the configuration's attainment past times a decentralized scheme of heterogeneous autonomous agents. Thus, the motto of generative social science, if you lot will, is: If you lot didn't grow it, you lot didn't explicate its emergence. (8)

Here is how Epstein describes the logic of ane of the most extensive examples of generative social science, the endeavor to sympathize the disappearance of Anasazi population inward the American Southwest nearly 800 years ago.

The logic of the exercise has been, first, to digitize the truthful history -- nosotros tin directly sentinel it unfold on a digitized map of Longhouse Valley. This information prepare (what actually happened) is the target -- the explanandum. The aim is to develop, inward collaboration alongside anthropologists, microspecifications -- ethnographically plausible rules of agent conduct -- that volition generate the truthful history. The computational challenge, inward other words, is to house artificial Anasazi where the truthful ones were inward 80-0 AD as well as come across if -- nether the postulated rules -- the imitation development matches the truthful one. Is the microspecification empirically adequate, to work van Fraassen's phrase? (13)

Here is a curt video summarizing the ABM developed nether these assumptions:

The artificial Anasazi experiment is an interesting one, as well as ane to which the constraints of an agent-based model are peculiarly good suited. The model follows residence place decision-making based on ground-map environmental information.

But this does non imply that the generativist interpretation is as applicable as a full general approach to explaining of import social phenomena.

Note kickoff how restrictive the supposition is of "decentralized local interactions" as a foundation to the model. Influenza A virus subtype H5N1 large proportion of social activity is neither decentralized nor purely local: the search for muons inward an accelerator lab, the advance of an armored partition into contested territory, the audit of a large corporation, preparations for a strike past times the UAW, the coordination of voices inward a large choir, as well as and then on, indefinitely. In all these examples as well as many more, a crucial business office of the collective conduct of the actors is the coordination that occurs through some centralized procedure -- a ascendency structure, a partition of labor, a supervisory system. And past times its design, ABMs look to endure incapable of representing these kinds of non-local coordination.

Second, all these simulation models travel on from highly stylized as well as abstract modeling assumptions. And the outcomes they pull capture at best some suggestive patterns that mightiness endure said to endure partially descriptive of the outcomes nosotros are interested in. Abstraction is inevitable inward whatever scientific work, of course; just ane time recognizing that fact, nosotros must abandon the catch that the model demonstrates the "generation" of the empirical phenomenon. Neither premises nor conclusions are fully descriptive of concrete reality; both are approximations as well as abstractions. And it would endure fundamentally implausible to hold that the modeling assumptions capture all the factors that are causally relevant to the situation. Instead, they stand upward for a particular stylized hypothesis virtually a few of the causes of the province of affairs inward question.  Further, nosotros accept practiced argue to believe that introducing to a greater extent than details at the soil degree volition sometimes atomic number 82 to meaning modification of the system-level properties that are generated.

So the catch that an agent-based model of civil unrest could demonstrate that (or how) civil unrest is generated past times the states of discontent as well as fearfulness experienced past times diverse actors is fundamentally ill-conceived. If the unrest is generated past times anything, it is generated past times the total prepare of causal as well as dynamic properties of the prepare of actors -- non the abstract stylized listing of properties. And other posts accept made the signal that civil unrest or rebellion is rarely purely local inward its origin; rather, at that topographic point are of import coordinating non-local structures (organizations) that influence mobilization as well as spread of rebellious collective action. Further, the fact that the ABM "generates" some macro characteristics that may seem empirically like to the observed phenomenon is suggestive, just far from a demonstration that the model characteristics suffice to create upward one's heed some human face of the macro phenomenon. Finally, the supposition of decentralized as well as local decision-making is unfounded for civil unrest, given the of import operate that collective actors as well as organizations play inward the success or failure of social mobilizations closed to grievances (link).

The signal hither is non that the generativist approach is invalid as a means of exploring ane particular prepare of social dynamics (the logic of decentralized local decision-makers alongside assigned behavioral rules). On the contrary, this approach does indeed render valuable insights into some social processes. The fault is ane of over-generalization -- imagining that this approach volition suffice to serve as a footing for analysis of all social phenomena. In a means the critique hither is just parallel to that which I posed to analytical sociology inward an before post. In both cases the job is ane of asserting priority for ane specific approach to social explanation over a release of other as of import just non-equivalent approaches.

Patrick Grim et al render an interesting approach to the epistemics of models as well as simulations inward "How simulations fail" (link). Grim as well as his colleagues emphasize the heuristic as well as exploratory operate that simulations mostly play inward probing the dynamics of diverse kinds of social phenomena.