Decomposability A Critical Issue in System Analysis & Adaptive-Policy Making

Transcription

1 Decomposability A Critical Issue in System Analysis & Adaptive-Policy Making Wolfgang Beyer Barry Newell Fenner School of Environment and Society The Australian National University

2 Outline The Complexity Dilemma Decomposability Collaborative Conceptual Modelling (CCM) Feedback Guided Analysis (FGA) Overview Template Example UCH Project Further Reading 2

3 Collaborative Conceptual Modelling Urban Health South East Asian Cities Wide range disciplines, experience, & allegiance Short exposure Burden of education Many challenges Focus on challenging & improving mental models 6 co-evolving activities System dynamics Complexity theory New protocols 3

4 The Complexity Dilemma A complex system is a set of parts (elements, actors) whose behaviour emerges from feedback interactions between these parts. You cannot understand the behaviour of a complex system by studying the behaviour of the parts taken separately. But, when you try to study the system as a whole, you are overwhelmed by its complexity. The system is too complex to be understood as a whole, but neither can it be understood as a set of disconnected parts that is the dilemma. 4

5 The Complexity Dilemma According to the complexity dilemma we are faced with two unsatisfactory, mutually exclusive options: study isolated parts (sub-systems) study the whole system But, perhaps there are cases where there is a third option. Question: Are there situations where it is possible to (a) study the dynamics of isolated sub-systems, but (b) still grasp the behaviour of the wider system? In such cases, there may be ways to escape the Complexity Dilemma. 5

6 Decomposability In The Sciences of the Artificial (1969) Herbert Simon talks about complex systems that are near decomposable. His primary example are hierarchic systems where one can distinguish between interactions among sub-systems, and interactions within sub-systems. He defines a near decomposable system to be one where the interactions between sub-systems (red), while not negligible, are weaker than those within the sub-systems (blue). Q C A K J F D E M P N B G H L S R 6

7 Decomposability Simon s main theoretical findings are that, in a nearly decomposable system, two propositions hold: 1) In the short run the sub-systems behave more or less independently, and 2) In the long run the behaviour of any one sub-system depends in only an aggregate way on the behaviour of the other sub-systems. [These facts have] the effect of separating the highfrequency dynamics of a hierarchy involving the internal structure of the [sub-systems] from the low-frequency dynamics involving interaction among [sub-systems]. (Simon 1969: 217) 7

8 Feedback Guided Analysis (FGA) Feedback Guided Analysis (Newell and Proust 2012; Newell 2015) is a three-stage CCM protocol. It provides a disciplined way to develop computable models, with well defined state variables and state-change processes, that maintain the overall feedback structure of the wider system. An application of the FGA protocol leads to a set of related sub-systems that form a near-decomposable hierarchy. These sub-systems are suitable for expression as low-order (N 10) system dynamics models. As such, FGA can help a system analysis group to escape the complexity dilemma. 8

9 Feedback Guided Analysis Whole System System Overview Template Specific System of Interest Problem Space SSoI Barry Newell & Katrina Proust ANU

10 A Near Decomposable Heirarchy A given Overview Template can guide the development of many Problem Spaces. Each Problem Space can generate many different Specific Systems-of-Interest (SSoI) Overview Template Problem Space A Problem Space B Problem Space C SSoI A1 SSoI B1 SSoI C1 SSoI A2 SSoI B2 SSoI C2 SSoI A3 SSoI B3 SSoI C3 10

11 Overview Template A CCM Overview Template is an influence diagram that specifies: the high-level decomposition (into major sub-systems) that you will consider in your analysis, and the dominant causal links that operate between those sub-systems. The structure of an overview template: should be as generic as possible, and must be scalable (scale free). 11

12 Overview Template This overview template represents a system decomposition that supports research in Planetary Health. 7 Human Health & Wellbeing 3 Policies Worldviews Environment 6 12

13 Overview Template is Scalable Human Health & Wellbeing 4 The template sub-systems can be scaled independently to match the problem space and the various SSoI. 7 Environment 3 Policies Worldviews Thus a single template can guide discussion of largescale problems (global climate change), small-scale problems (an individual s efforts to remain healthy), and cross-scale problems (impact of climate change on an individual s health). 13

14 Human Health & Wellbeing 4 Overview Template Worldview Sub-System 7 Environment 3 Policies Worldviews We will take the worldview of an individual or society to be an interrelated, comprehensive set of variables that reflects assumptions about how the world works. These variables measure the state of the community s knowledge, understanding, mental models, formal models, and their assumptions (theories) about cause and effect. It includes variables that represent the state of community beliefs, values, and ethics. 14

15 Human Health & Wellbeing 4 Overview Template Policy Sub-System 7 Environment 3 Policies Worldviews We will take the policies of an individual or a society to be a comprehensive set of rules that govern behaviour. Thus the policy sub-system includes variables that indicate the focus and power of formal laws, institutions, and regulations. The variables of the policy sub-system guide human actions via goals and sets of decision rules. Some of these rules are followed (or enforced) consciously, others seem to be just common-sense and are followed unconsciously. 15

16 Human Health & Wellbeing 4 Overview Template Environment Sub-System 7 Environment 3 Policies Worldviews We will take the environment sub-system to encompass variables that measure the state of both ecosystems and the built environment. When we are dealing with individuals, or small groups of people, we will assume that their environment also includes other people. The variables include those related to the nature and extent of physical infrastructure and the prevalence of devices such as motor vehicles, television sets, cell-phones, air-conditioners, and the IoT. 16

17 Human Health & Wellbeing 4 Overview Template Human Health & Wellbeing Sub-System 7 Environment 3 Policies Worldviews We will take the health and wellbeing sub-system to encompasses all the relevant physiological and psychological variables, plus wellbeing variables such as security, comfort, and happiness. In addition to variables that measure the incidence of specific diseases, physical fitness, and the average level of mental health, this sub-system includes variables related to economic security and opportunities for advancement. 17

18 Human Health & Wellbeing 4 Overview Template Link 1: Policy Making 7 3 Policies Worldviews Planning, policy-design and goal-setting activities. These activities are shaped by the community s worldviews. Environment 6 The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 18

19 Human Health & Wellbeing 4 Overview Template Link 2: Experiential Learning 7 Environment 3 Policies Worldviews Observations and assessment of the state of the policy subsystem, and feedback of insights that can affect the state of the community s worldviews. The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 19

20 Human Health & Wellbeing 4 Overview Template Link 3: Human Actions 7 Environment 3 Policies Worldviews Individual and group activities that affect the community s overall physiological, psychological, and social functioning. The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 20

21 Human Health & Wellbeing 4 Overview Template Link 4: Experiential Learning 7 Environment 3 Policies Worldviews Observation and assessment of the evolution of population health and wellbeing. These monitoring activities can lead to modification of the community s worldviews. The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 21

22 Human Health & Wellbeing 4 Overview Template Link 5: Human Actions 7 3 Policies 2 Worldviews Individual and group activities that affect the state and functioning of the environment. 5 1 Environment 6 The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 22

23 Human Health & Wellbeing 4 Overview Template Link 6: Experiential Learning 7 Environment 3 Policies Worldviews Observation and assessment of the state and evolution of the environment. These monitoring activities can lead to modification of the community s worldviews. The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 23

24 Human Health & Wellbeing 4 Overview Template Link 7: Co-Effects 7 3 Policies Worldviews Natural processes whereby changes in the environment directly affect human health and wellbeing. Environment 6 The blocks of text represent the interacting sub-systems, and the arrows represent the processes and mechanisms whereby changes in the levels of the variables in one subsystem affect the level of the variables in another. 24

25 Example Urbanism, Climate Change & Health (UCH) 25

26 UCH Overview Template 26

27 Technology Problem Space 27

28 Transport Sub-System 28

29 RAC Sub-System 29

30 Food Sub-System 30

31 Further Reading Simon, H.A., 1969, The Sciences of the Artificial (London: MIT Press). Newell, B., 2015, Towards a shared theoretical framework, in R. Dyball & B. Newell, Understanding Human Ecology: A systems approach to sustainability (London: Routledge). Newell, B., and Proust, K., 2012, Introduction to Collaborative Conceptual Modelling, Working Paper, ANU Open Access Research. 31