Hi all,Interesting discussion! To me, one of the main characteristics of an agent is agency - the ability to act independently. I think any definition of an agent or agent-based/multi-agent modeling should reflect it. Apologies for not including a reference.Best,Garryas an alternative -- given that the initial question was "what are some different ways of defining agents?" -- in a recent article we explored agents from a case-comparative perspective, going back to Becker and Ragin's famous edited book, What is a Case?" And Byrne and Ragin's Sage Handbook of Case-Based Methods. We define agents as cases doing things and as complex systems.
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From: News and discussion about computer simulation in the social sciences <[log in to unmask]> on behalf of Robert Zupko <[log in to unmask]>
Sent: 17 April 2019 15:20:42
To: [log in to unmask]
Subject: Re: [SIMSOC] Definition of an agentAll:
This is a very interesting question. Perhaps its due to the transdisciplinary nature of my dissertation (touching on both social simulation and chemistry), I take a fairly minimalist approach to defining ABM and agents, "[ABM] is a computational technique in which the system is described though agents’ interactions with the environment and amongst themselves (Axtell, 2000; Epstein and Axtell, 1996)." An "agent" in turn is then described as an entity within the system being described. I suppose an broader question for a canonical definition of ABM might be there should be a distinct meaning between ABM / IBMs or if the terms are in fact interchangeable as seems to be the practice.
Regards,Robert Zupko
Dear all,
I am inclined to agree with Edmund, not least because I see Social Simulation as an interdisciplinary endeavour – being too precise about how we define what an agent is (and/or what an agent-based model is) risks shutting people out for possibly quite arbitrary reasons. That said, it would be interesting to review work claiming to be ‘agent-based’ to look at different classifications of ‘agent’ and (with a nod to Jim Doran’s later message), if we had access to computer code, at the formal algorithmic properties they have. A bottom-up approach to the definition would be so much more appropriate… :-)
With Jiaqi Ge, I have tried adopting a ‘Dennettian’ approach in a rather obscure reference here: https://www.naturvardsverket.se/Documents/publikationer6400/978-91-620-6695-6.pdf?pid=16935 (see p. 51). We describe agency as a narrative concept – if it make sense in a particular context to give agency to something or someone, then it’s an agent.
In this article (https://link.springer.com/content/pdf/10.1007%2Fs10707-018-00340-z.pdf), agent-based models are defined (not authoritatively) thus:
“ABMs must at least explicitly represent the following: a ‘sufficient’ number of entities (sorites paradox notwithstanding) individually; each such entity having some attributes that are, in some sense, ‘theirs’ and not others’; each such entity also having some dynamics that they are, in some sense, responsible for causing; with these dynamics having the potential to cause (directly or indirectly) changes to the attributes belonging to other such entities.”
Gary
From: News and discussion about computer simulation in the social sciences <[log in to unmask]> On Behalf Of Edmund Chattoe-Brown
Sent: 17 April 2019 11:31
To: [log in to unmask]
Subject: Re: [SIMSOC] Definition of an agent
Dear All,
I would take a different tack and say that one of the reasons why these sorts of definitional tasks are so difficult and controversial is because it is not clear what the _aim_ of definition is. What do we "gain" when we define (rather than just "illustrate") the concept of agents? You cannot remove some aspects of reality that you don't approve of just by definition (or people will argue with you endlessly). So how could one adjudicate "scientifically" the dispute about whether an agent must/needn't have "advanced reasoning capabilities?" (Which, of course, is another contestable definition and so on!)
An example. We can "define" a household as two married adults living in the same house with dependent children (and marriage and dependent also have formal definitions). Then we can do some statistics to show (perhaps) that this kind of household is correlated with educational success. But then we have to allow that it is not being married that creates this correlation but whether the household is "harmonious" (which some cohabitation is and some marriage is not) and whether the parents engage with and support their children's schooling (ditto). We have done the research starting from a clear definition (and that is good) but the definition has not "saved us" from the complexities of social life behind it. Given than many ABM are not so empirical, we cannot ask whether one definition rather than another generates "better designed" research or "better fit with data" (or some other "worthy" outcome) and that is another reason why (IMO) such discussions tend to be relatively unproductive.
All the best,
Edmund
--
Edmund Chattoe-Brown
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