Human Agency in Mathematical Models for Geoanthropology
In many complex systems, as e.g. in physics, ecology, finance, or history, phases of relatively stable states often alternate with with rapid shifts, as phase transitions, revolutions, the emergence or extinction of species etc. Physics, as well as e.g. classical economics (adopting concept from physics), tends to see these stable states as equilibria, i.e. as the result of some optimisation process. From the point of view of evolution theory, there are no equilibria in this sense, as the stochastic processes and feedbacks of evolution constitute continuous development all the time; however also in the fossil record, stable phases of populations with little evolutionary change alternate with phases of relatively rapid phases of branching of species; this has been described by Eldrege and Gould in the theory of punctuated equilibria. Concepts very similar to the one of punctuated equilibria can be found in political theory and history, where the phases of fast change are often called critical junctures. Whereas there are a comprehensive mathematical descriptions for the dynamic behaviour or physical systems between equilibria in physics, a theory of critical junctures has not been represented in mathematical terms.
Relevance for Geoanthropology
The concept of critical junctures in history is usually used for the idea that periods with strong institutions are relatively stable. At a critical juncture, however, institutions become week or dissolve, and human agency of individuals or groups has a much larger impact on the future course of history than in the times in between; the amount of options for possible continuations is thought to be increased during those times. As humans have become a factor in the evolution of the earth system, this means that representations of 'human agency' has to be taken up in human-earth-system modelling. Some research questions following from this are:
- In how far can methods from modelling systems in the natural sciences be taken over for modelling social-technical-ecological systems, what are the limits of those approximations?
- How to formulate a mathematical description of critical junctures?
- Can the concepts of punctuated equilibria or critical junctures help to explain the trajectory that led to the Anthropocene?
- How does modelling possible futures influence the decisions taken and thus possibly influence the course of the system?
Our Approach to the Research Questions
There is not any broad and comprehensive usage of mathematically formulated theories for (aspects of) social systems. Sometimes concepts from other fields are used to describe certain phenomena, as e.g. the concept of diffusion from physics in models of opinion dynamics. Due to the heterogeneity of actors and interactions and the lack of general laws, social systems have often rather been simulated than analysed using a mathematically closed formulation similar to laws of motion.
Simulation is often performed with agent-based models (ABMs). These models assume decision algorithms for their micro entities, the 'agents', and then simulate the macro behaviour of the system from theses rules. Even for systems of very moderate complexity, there is not any analytical understanding of how the emergent behaviour comes about. It is clear, however, that ABMs can be seen as stochastic processes. Our approach for tackling the above research questions about the representation of human agency in mathematical models therefore starts from ABMs and tackle questions as:
- How can we better analytically understand the simulation outcomes from ABMs? How does this enable us the understand which structural features foster or inhibit rapid changes on the macro level?
- How can we use such understanding to possibly change or design structures in the real systems that better stabilize systems or e.g. foster certain socio-technical transitions?
- How can we better represent human decisions and actions in such systems in (agent-based) models and maybe also take into account the impact of imagining possible futures using model predictions on the decisions of actors?
Relation to Other Research Projects at MPI-GEA
This research project aims at understanding fundamental changes of the technosphere in an analytic way and contributes to the endeavour of building co-evolutionary coupled human-earth-system models.
In the Decision Theatre, models are discussed and further developed with all kinds of stakeholders. Observing how the participants of Decision Theatre events interact with model scenarios will give more ideas about how to account for the impact of model building for possible future scenarios. Further a better understanding of which structural elements of ABMs increase stability or foster change can help design possible interventions (such as e.g. policy measures) for these purposes. For that, however, the models have to be empirically founded, which can also be better achieved with the help of the Decision Theatre.
