Systems Theory
A system refers to an integrated whole whose properties or characteristics result from the relationships between its parts.
A system contains different levels of complexity, and different kinds of process operate at each level. At the various levels, the phenomena exhibit properties that do not exist at lower levels: the taste of sugar does is not contained in the carbon, hydrogen and oxygen atoms that comprise it. In the early 1920s a philosopher named C.D. Broad introduced the term "emergent properties" for properties that emerge at higher levels of organization but not at lower levels.
Thus, the characteristic properties of the whole arise not from its parts alone, but from the interactions among the parts; these properties are destroyed when the system is dissected into isolated elements. Hence, systems that exhibit emergent phenomena cannot be analyzed using the standard approaches of reductionist science. Hence, for example, a randomized controlled trial, which imposes strict controls and seeks to isolate certain elements of a system from their environment, may not represent the way the system will operate when returned to its natural setting.
While biologists initiated the systems approach, it quickly spread to gestalt psychologists interested in learning and perception, and to physicists exploring quantum mechanics. Each of these disciplines needed an alternative to linear, reductionist thinking, a way to go beyond the earlier Cartesian paradigm that held that the whole can be understood from an analysis of its parts. Systems thinking holds that the properties and functioning of parts are not intrinsic, but can only be understood within the organizational context of the larger whole. This reverses the reductionist approach which held that the whole is to be understood from an understanding of its parts. As any gardener knows, the health of plants depends greatly on the selection of the other plants around them; a garden is a functioning whole and cannot be analysed in terms only of the component plants. A systems approach to cell biology would combine insights from functional and structural genomics, proteomics, etc., to permit a model of the cell behaviour that shows what happens when there is a change in the cellular environment. Ecosystems refer to communities of organisms and their physical environment interacting as an ecological unit. It’s a shift from studying parts to studying relationships. Indeed, the very idea of an object holds only at a particular level of analysis: all "objects" are relationships between component relationships. Objects can be seen as networks of nodes (here organisms such as a plant). Each node, when magnified, also appears as a network of nodes, and so on. The systems viewpoint shifts attention from the nodes towards the way they are networked.
There is a relevant distinction between "open" and "closed" systems. Closed systems refer mainly to mechanical systems, but the term has been used in social sciences when discussing self-contained systems. In closed systems, such as a machine, there is an inevitable dissipation of energy and a trend from order to disorder, eventually reaching a static equilibrium. For example, some mechanical energy is always dissipated into heat that cannot be completely recovered. "Entropy" refers to this tendency for a closed system to move toward a random (less organized) state in which there is no further potential for energy transformation or work. This is the field of the second law of thermodynamics: an isolated or closed system proceeds spontaneously towards ever-increasing disorder. Open systems, by contrast, are not covered by the second law; biological and social systems receive energy, information and material that allow them to offset the process of entropy and stay alive; they become self-organizing.
Examples of the value of a systems approach abound in population health. The recent failed attempts at health care reform in Canada offer an example. During the 1990s, it was argued that there were too many doctors and nurses; training programme enrolments were cut and nurses were laid off. Apparently no-one anticipated how the system would react at a higher level of organization. To give just one example, the nursing unions gave priority to senior nurses and so several generations of younger nurses left for other places or careers; the average age of nurses rose sharply. The work-load did not decline, and the additional strains of being under-staffed lead these senior nurses to react negatively to having to do the type of work their junior colleagues had previously done. Many took early retirement. Meanwhile, many younger nurses had found other work, making it hard to find replacements, compounding the shortages.
Defining criteria for systems thinking (From F. Capra. The web of life. New York, Anchor Books, 1996, chapter 3)
1. Shift from the parts to the whole: the part cannot be understood in isolation from the whole. Essential, systemic properties are properties of the whole, which none of the parts have.
2. Attention shifts back and forth between systems levels; systems are nested within other systems. Each level represents differing levels of complexity, but similar concepts may be applied to understand different levels. You can, for example talk of stress on my femur, my body, my family or on my neighbourhood.
3. Cartesian, mechanical thinking holds that the behaviour of the whole can be understood from a study of the parts. If we want to understand the Canadian health care system, we could interview the government ministers, the hospitals and the health professionals that compose it. Systems thinking holds that the properties of the parts are not intrinsic to them, but can only be understood in the context of the whole; you will not understand the reactions of doctors unless you study their behaviour in the context of the health care reforms.
4. Knowledge is a network of ideas; ideas are a network or a juxtaposition of concepts, and so on... In systems thinking, knowledge is no longer seen as a building ("the structure of knowledge"), but as a network. Physics is no longer seen as a fundamental science – it just concerns a different systems level.
5. While Cartesianism held science to be objective, the systems approach holds that epistemology forms an integral part of natural phenomena. All knowledge is approximate, and is viewed from a particular perspective. Science can never provide any complete and definitive understanding.
Link to Overview of history of biological ideas: ways of thinking about living beings.
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