Accepted Manuscript Stigmergy 3.0: From Ants to Economies Margery J. Doyle, Leslie Marsh PII: S1389-0417(12)00036-8 DOI: http://dx.doi.org/10.1016/j.cogsys.2012.06.001 Reference: COGSYS 400 To appear in: Cognitive Systems Research Please cite this article as: Doyle, M.J., Marsh, L., Stigmergy 3.0: From Ants to Economies, Cognitive Systems Research (2012), doi: http://dx.doi.org/10.1016/j.cogsys.2012.06.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
a L-3 Communications, Link Simulation and Training, Wright-Patterson AFB, OH 45433-7905, USA
b Office of the Dean, Faculty of Medicine, The University of British Columbia, Vancouver, B.C., V6T 1Z3, Canada
Abstract: The editors introduce the themed issue “stigmergy 3.0”
Keywords: Stigmergy; Complexity; Pierre-Paul Grassé; Human stigmergy; Social externalism
According to Andy Clark “[M]uch of what goes on in the complex world of
humans, may thus, somewhat surprisingly, be understood in terms of so-called stigmergic
algorithms” (Clark, 1996, p. 279; 1997, p. 186). Pierre-Paul Grassé, the brilliant mind
who first conceptualized the notion probably wouldn’t disagree (Grassé, 1959). Grassé
was as much a zoologist as he was an entomologist. Under his editorship the monumental
(17-volume) Traité de Zoologie, Anatomie, Systématique, Biologie was guided.1
Arguably one of the most ambitious and audacious publishing endeavors ever undertaken
in a science (Wing, 1950), it has come to be known affectionately as le Grassé. It is with
the recognition of this fact that Grassé would perhaps be gratified, if not surprised, that
the term “stigmergy” has achieved such wide currency and that he’d agree that perhaps:
[T]he correspondence between human and animal rationality is not a loose analogy but a deep biological similarity, albeit the degree of stigmergy reaches its most hypertrophic form in the human species” (Allen et al. 2012, p. 50).
Grassé sought to understand the mechanisms underlying the emergence, regulation, and
control of collective activities in social insects. Specifically, Grassé’s research sought to
development and much more besides. No longer is the concept of stigmergy associated
solely with ant- or swarm-like “agents” with minimal cognitive ability or with creatures
of a somewhat higher cognitive capacity such as fish or birds or sheep. New forms of
stigmergy have been identified through the affordances of digital technology: Google’s
recommendation algorithm, Amazon’s filtering algorithm, wiki, open source software,
weblogs, and a whole range of “social media” are now deemed as essentially stigmergic.
Even this co-authored contribution can be considered an instantiation of stigmergy.
It was a watershed paper by “Van” Parunak (2005), however, that gave wing to
what we term “stigmergy 3.0” – emphasizing the ubiquitous human-human stigmergy
that Clark so presciently recognized some eleven years before. Social theory,
philosophical and sociological, in its attempt to make sense of individual-group ontology
and dynamic has often taken inspiration from natural history. Though biological inspired
political theory has long since been discredited, evolutionary biology has inspired a lively
multidisciplinary field (Grosan & Abraham, 2006). However, the “stigmergy” story goes
back at least to the two giants of the Scottish Enlightenment – David Hume and Adam
Smith.
E.O. Wilson’s “sociobiology” is in some respects, as Wilson himself concedes, a
striking vindication of Humean naturalism, offering a scientific basis for Hume’s
speculative anthropology. The congruence between Wilson’s “hard-core” and “soft-core”
altruism and Hume’s “natural” and “artificial” virtues presents a rather tidy fit (Wilson,
1978, pp. 156-57).2 We will return to Wilson later. For our immediate “stigmergic”
purposes, it was Smith’s “invisible hand” metaphor that seemed to capture the related
notions of self-regulation, emergent or spontaneous order (Smith, 1776/1904;
1759/1976).3 But it was through Friedrich Hayek, Smith’s great intellectual descendant,
that the interrelated modern notions of collective intentionality, distributed knowledge,
2 Wilson’s sociobiology was seen in some quarters to have socio-political implications or in common parlance was deemed as not “politically correct.” For a detailed account of the Wilson sociobiology controversy see Segerstrale, 2000 who takes the controversy to be a precursor to the “science wars” that broke out in the late 1990s. 3 The significance of Smith’s famous “invisible hand” metaphor is highly contested (see the symposium with luminaries such as Nozick, 1984; Cosmides & Tooby, 1984; Rothschild, 1984; Williamson, 1984).
situated cognition, spontaneous order, and complexity studies received its most powerful
application and endorsement (Marsh, 2010). Consider this. The progenitors of the recent
“extended mind” industry, Andy Clark and David Chalmers (1998), acknowledge Herbert
Simon as providing some inspiration for their externalism. Simon, no slouch himself, in
turn credited and endorsed Hayek for providing the key philosophical presupposition that
underwrites cognitive extension:
No-one has characterized market mechanisms better than Friedrich von Hayek . . . [His] defense did not rest primarily upon the supposed optimum attained by them but rather upon the limits of the inner environment – the computational limits of human beings (Simon, 1996, p. 34).
Herein lies a key idea that we will return to later. Hayek’s, Simon’s (and Clark and
Chalmers’ minimal) social externalism runs the shared presupposition that mind is
constrained in its computational capacity to detect, harvest, and assimilate “data”
generated by the infinitely fine-grained and perpetually dynamic characteristic of
experience in complex social environments. For Hayek knowledge (and as a
consequence, freedom) exist within a manifold network of spontaneous or complex
adaptive orders, orders in which situated agents are perpetually responding to and
redefining their environment. Spontaneous orders are, in effect, coordination and
“communications systems,” mechanisms for the cooperation among strangers with
differing wants, preferences and interests, a mechanism that offers epistemic (and
computational) efficiencies in that knowledge is distributed and dynamic (Hardwick &
Marsh, in press). The moral of Hayek and Simon’s story is that “perfect” knowledge is
unnecessary, impracticable and indeed irrelevant. To all intents and purposes, this
insight is co-extensive with a stigmergic sociality, the mechanism at work in complex
sociality that, in effect, augments or scaffolds cognition (Clark, 1997; Marsh, in press a).
Another strand to the story that has a more recent and an independent provenance
begins of course with Grassé (Noirot, 1985). Not too dissimilar to Adam Smith, Grassé
sought to understand how one could reconcile behavior at the individual level (given that
individuals are constrained by knowledge and material resources) with the global/societal
level of the termite colony. Prima facie, behavior at the individual level appeared to be
chaotic, which of course is at odds with the visibly impressive structures that only a
highly organized colony of termites could achieve. What Grassé discovered in the
coordination and regulation of termite colonies, is the phenomenon of indirect
communication mediated by modifications of the environment – which he termed
“stigmergy” (Grassé, 1959). This definition constitutes the canonical formulation of the
concept (for more details on the concept’s development and variants thereof see Marsh &
Onof, 2008). Grassé observed that the coordination and regulation of building activities
did not depend on the individual “agents” themselves but was informed by the current
state of structure itself. In other words, the environment acts a kind of distributed memory
system.
Some object to the extension of Grassé’s insight to the human–human world
(Shell & Mataric, 2003; Tummolini & Castelfrananchi, 2007). It is our view that Grassé’s
concept of stigmergy is a classic case of an essentially contested notion. By this we
simply mean that different theorists stress different stands or elements in different
contexts inspired by a paradigmatic application – in this case, Grassé’s fairly narrow
application of the underlying broader notion, filling this role (Marsh & Onof, 2008). Even
if one considers human activity as quasi-stigmergic, the kernel of the idea remains intact:
that is, in Clark’s words “the use of environmental conditions as instigators of action and
the overall ability of the group to perform problem-solving activity that exceeds the
knowledge and the computational scope of each individual member” (Clark, 1997, p.
234, note 9). Or in Holland & Melhuish’s words “All that is necessary for stigmergy to
occur is for the outcome of the behavior of the relevant agent to be appropriately affected
by previous environmental changes” (Holland & Melhuish, 1999, p. 174). For all intents
and purposes, this was exactly the line of business that classical theorists such as Adam
Smith (the trite “father of economics”) and his contemporary Adam Ferguson (“the father
of modern sociology”)4 were in when emphasizing the notion of spontaneous order.
Don Lavoie, an Austrian school5 economist, saw the resonance of swarm behavior
to human-human stigmergy in no uncertain terms. Like Hayek and Simon, Lavoie accepts
the presupposition of what Colin McGinn has famously termed “cognitive closure”
(Lavoie, 1985, pp. 65-66, 68-69; McGinn, 1989). That is, if mind is constitutionally
delimited, then it must somehow augment its epistemic and computational capacity:
adaptive evolutionary imperatives demand it.
Though Lavoie doesn’t ever invoke the term stigmergy one should be in no doubt
that the features of mass coordination across all domains of sociality are for him
stigmergic – indeed, the terms “tradition” and the “market” are shorthand for stigmergic
sociality (Lavoie, 1985, p. 29). Lavoie makes the link between “mass communication”
and the knowledge problem that Hayek is rightly famous for (Lavoie, 1985, pp. 27-28;
Marsh, in press) and focuses on the mechanism of coordination. For Lavoie as well “the
4 Willcox & Arnstein, 1996. 5 The Austrian tradition of economics (see Littlechild, 1990) emphasizes the subjective, socially-embedded quality of action along with the decentralization of knowledge (tacit and propositional) and is fully in tune with current non-Cartesian science as represented by Thompson (2007) and Noë (2008). Analytical social epistemology is also now taking social externalism seriously and is referencing the suggestive “extended mind” thesis (Goldberg, 2007; Prichard, 2010).
similarity between insects and man is greater in this respect than it may appear” and
moreover “the human analogue of the insects’ pheromone is the expenditure of money in
market exchanges” (Lavoie, 1985, pp. 69-71, 72). He goes on:
The principle the sociobiologists call “mass communication” reveals how partial, localized knowledge on the part of a termite in one part of a colony can be merged in such a way that the system’s overall allocation of resources is informed by more knowledge than any one participant to the process can possess. It seems to me that the very same kind of mass communication is the principle that operates in market systems (Lavoie, 1985, p, 76.)
In language reminiscent of Hayek, Lavoie is of the view that:
These diverse spontaneous orders, from primitive insect societies to such complex institutions as markets and science, all exhibit as a basic organizing principle a competitive process of discovery whereby each participant both actively contributes and passively responds to signals (Lavoie, 1985, p. 86).
In other words, the stigmergic interest lies in the stochastic spread of a marker through a
population of strangers whereby a strong pheromone trail will translate into heightened
awareness of say a food source (ants) or of a product (human-human). The downside to
this phenomenon, as Clark rightly warns, is the risk of a “dysfunctional communal
narrowing of attention” that can be self-fulfilling (Clark, 2003, p. 158).6 Put another way,
“path-based idiosyncrasies may become locked in as material artifacts, institutions,
notations, measuring tools and cultural practices” (Clark, in press, MS pp. 44, 62).
Let’s close the circle and return to our ant friends. For Simon, ants (and indeed
humans) viewed as behaving systems, are really quite simple. The apparent complexity of
the ant’s behavior is largely a reflection of the complexity in which it finds itself:
We watch an ant make his laborious way across a wind- and wave-molded beach. He moves ahead, angles to the right to ease his climb up a steep dune let, detours around a pebble, stops for a moment to exchange information with a compatriot . . . [I]t is a sequence of irregular, angular segments – not quite a random walk, for it has an underlying sense of direction, of aiming toward
6 Related (but distinct) phenomena: (i) confirmation bias, (ii) conformity bias, (iii) groupthink. They are different in nature and origin, but collectively reinforce the same aggregate effect. Thanks to Georg Theiner for pointing this out.
a goal . . . [H]e has a general sense of where home lies, but he cannot foresee all the obstacles between. He must adapt his course repeatedly to the difficulties he encounters and often detour uncrossable barriers. His horizons are very close, so that he deals with each obstacle as he comes to it . . . [V]iewed as a geometric figure, the ant’s path is irregular, complex, hard to describe. But its complexity is really a complexity in the surface of the beach, not a complexity in the ant (Simon, 1996, p. 51).
The analogous environmental complexity for humans is epistemic: it is distributed and
modulated through practices, traditions, and institutions that arise through cooperative
endeavors. Consider this extract from the grandee of situated theorists:
[T]his power of culture and language to shape human subjectivity and experience belongs not simply to the genetic constitution of the individual, but to the generative constitution of the intersubjective community. Individual subjectivity is from the outset intersubjectivity, as a result of the communally handed down norms, conventions, artifacts, and cultural traditions in which the individual is always already embedded. Thus the internalization of joint attention into symbolic representations is not simply an ontogenetic phenomenon, but a historical and cultural one (Thompson, 2007, p. 409).
On Thompson’s account, sociality can only be mediated, albeit imperfectly (not in high-
fidelity), through a web of social artifacts that contains its own immanent standard of
epistemic weight regarding its methodological, conceptual and empirical problems. Or as
another non-Cartesian externalist social philosopher so aptly put it, practices or traditions
are not stable compositions of easily recognised characteristics . . . they are footprints left behind by agents responding to their emergent situations, footprints which are only somewhat less evanescent than the transactions in which they emerged (Oakeshott, 1975, p. 100).
The diverse theorists invoked are bound together by the idea of informational flow
(traditions and practices as external artifacts or “downstream” epistemic engineering as
Sterelney, 2003 puts it) between generations and the idea of cooperation conceived as
distributed cognition (Hutchins, 1995). Stigmergy can also be understood as informing
these downstream coordination systems writ large. In short, since mind is intrinsically
constrained in its computational capacity to assimilate the infinitely fine-grained and
perpetually dynamic characteristic of human experience, sociality functions as a kind of
distributed “extra-neural” memory store manifest as dynamic orders. Furthermore, mind
and the broad manifold of sociality are in effect co-evolved spontaneous orders.7 Or put
in more contemporary terminology “patterns of practice at the level of social interaction
correlate in relevant ways with neural and psychophysical patterns . . .” (Roepstorff et
al., 2010).
We began with Clark and so we end with Clark. In summarizing the significance
of stigmergy which Clark also terms as indirect emergence, he writes: “Such . . .
emergent collective phenomena . . . can support complex adaptive behaviors without the
need for leaders, blueprints, or central planners” (Clark, 1997, p. 76). The “mouldy old
dough” Adam Smith and more recently Friedrich Hayek, Michael Oakeshott and Herbert
Simon – would not disagree in the very slightest.
~~~~~~~~~~~~~~~~~~~~
As we write this introduction the tenth anniversary of the Twin Towers attack in
New York City is being commemorated. So what is the significance of this profoundly
shocking event for the concept of stigmergy? In accordance with this issue’s theme, Ted
Lewis (2012) examines social networking as a paradigmatic example of human cognitive
stigmergy – his case study being the 9-11 terrorist network – exploited to such horrific
effect. The case study offers a theory of human-human stigmergy set against a
background of network theory, examining the flow of information when factoring in
strong leader phenomenon and network resilience against dissent.
Saurabh Mittal’s (2012) paper puts Discrete Event System Specification (DEVS)
center stage. Mittal’s paper – though empirical – is cognizant of some slippery 7 A much more detailed account of cognitive closure and sociality is in the offing, see Marsh, forthcoming.
philosophical topics – for example related notions of complexity and emergence. Mittal
rightly understands that “stigmergy talk” is a species of “complexity talk” but that the
latter is a highly tricky notion to articulate. Mittal builds upon the work of DEVS prime
mover Bernard Zeigler, taking the view that DEVS formalism that lends itself to a study
of complex adaptive systems.
Alert to those skeptical of extending stigmergy to include the human realm or to
use philosophical jargon, those skeptical of the “extensional adequacy” of the concept
(the set of features that identify the sort of things the concept applies to), Lars Rune
Christensen (2012) sensibly wants to ensure that the concept is not so broad as to become
emptied of all meaning. Christensen takes the view that stigmergic coordination is highly
useful in analyzing the complexity typically involved in human building processes.
The next two papers concern online stigmergy. Janet Marsden (2102) examines
the burgeoning world of stigmergic (or spontaneous or emergent order or complex
adaptive systems if you like) behavior within a digital or virtual context. Marsden’s case
study has its roots in the rather unsavory post-election violence in the Kenya of 2008.
Inspired by the distributed mapping of the violence, the open source “Ushahidi Platform,”
virtual organizations are examined in the context of stigmergic self-organizing responses
to critical incidents.
On a lighter note, Jimmy Secretan (2012) examines the stigmergic dimensions of
online interactive creativity through the lens of Picbreeder whereby users collaboratively
create images with significant complexity without explicit communication, i.e. through
stigmergic interaction. In both Marden’s and Secretan’s articles the traditional
understanding of collaborative creativity is being challenged by online creative
interaction making good on Parunak’s (2005) paper that we singled out for special
mention.
Acknowledgments
A big thank you to this issue’s referees – they have provided a sterling community service given the often highly technical nature of the topic layered with cross-disciplinary interest not to mention the ever-shifting sands of the topic. The referees were: Myriam Abramson (Naval Research Laboratory, Washington, D. C.), Anamaria Berea (The Krasnow Institute for Advanced Study, George Mason University, Fairfax), Sven Brueckner (Senior Research Scientist, Vector Research Center, Detroit), Luís Correia (Universidade de Lisboa - Faculdade de Ciências, Departamento de Informática Campo Grande, Lisboa), Péter Érdi (Henry R. Luce Professor, Center for Complex Systems Studies, Department of Physics/Department of Psychology, Kalamazoo College, Kalamazoo), Simon Garnier (Department of Ecology and Evolutionary Biology, Princeton University, Princeton), Carlos Gershenson (Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México), David Hales (Faculty of Mathematics, Computing and Technology, The Open University, Milton Keynes), Steven Hall (Research Professor, MOVES Institute, Naval Postgraduate School, Monterey), David Hardwick (Office of the Dean, Faculty of Medicine, The University of British Columbia, Vancouver), Michael Kaisers (Department of Knowledge Engineering, Maastricht University), Brian Jackson (Senior Physical Scientist, RAND Corporation, Washington D. C.), Jessica Lindblom (Senior Lecturer in Cognitive Science, Institutionen för Kommunikation och Information/School of Humanities and Informatics Högskolan i Skövde/University of Skövde), Steve Phelps (Centre for Computational Finance and Economic Agents, University of Essex), Nathalie Prevost (Simon Fraser University, Cognitive Science Lab), Alessandro Ricci (Dipartimento di Elettronica, Informatica e Sistemistica/ Facoltà Due di Ingegneria, University of Bologna), Samir Schopra (Department of Philosophy, Graduate Center and Brooklyn College, City University of New York), Mamadou Seck (Systems Engineering Section, Department of Technology, Policy, and Management, Delft University of Technology), Carrie Solinger (School of Information Studies, Syracuse University), Forrest Stonedahl (Professor of Computer Science & Mathematics, Centre College, Danville), Peter Suber (Director, Harvard Open Access Project/Berkman Fellow/Professor of Philosophy at Earlham College), Tarja Susi (Skövde Situated Cognition and Artificial Intelligence Research Lab, University of Skövde), Georg Theiner (Department of Philosophy, Villanova University), Andreas Tolk (Professor for Engineering Management and Systems Engineering/ Modeling, Simulation, and Visualization, Old Dominion University, Norfolk), Karl Tuyls (Professor, Artificial Intelligence, Department of Knowledge Engineering, Maastricht University), Adelinde Uhrmacher (Institut für Informatik, Universität Rostock) and Tina Gwoing Yu (Professor, Department of Computer Science, Memorial University of Newfoundland). References Allen, C. , Todd, P. M., & Weinberg, J. M. (2012). Reasoning and rationality. In E. Margolis, R. Samuels
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