Function
What a system or component does — its role, purpose, or activity. Different structures can perform the same function.
Formal Definitions
Mobus & Kalton (2015):
“The collective effect of the process is also called the ‘function’ of the system. The processes inherent in the bits and pieces of a rock, strong chemical bonding, produce its qualities of hardness and stability over time. The processes of digestion in your alimentary track function to acquire nutrients for your body’s maintenance.”
(Principles of Systems Science, Section 3.4.2.1.2.1)
“A system performs its function in the sense that it produces outputs, some of which are products in that they are inputs to other entities in the environment that need those inputs as resources, while others might be actions, behaviors, that contribute to the success of other entities in the environment.”
(Section 3.4.2.2.1)
“The purpose of a system is to ‘fit’ into its supra-system in the sense that it produces actions or products that keep the whole supra-system in dynamic stability.”
(Section 3.4.2.2.1)
Bunge (1979):
“X and Y are coordinated if they jointly contribute to the integrity of a system.”
(A World of Systems, p. 38, Chapter 1)
Bunge approaches function through coordination — functional components are those whose activities jointly maintain systemic coherence.
Synthesis
Mobus defines function as the collective transformative effect of system processes — what the system does relative to inputs/outputs and its contribution to supra-system stability. Bunge emphasizes functional contribution to systemic integrity. Mobus is more explicit about teleonomic fit (purpose-like behavior without purpose); Bunge emphasizes the maintenance of coherence through coordination.
Key Insight
Function is about relationship, not isolation. A heart’s function (pumping blood) only makes sense in the context of the circulatory system, which only makes sense in the context of the organism. Function is always function for something.
Explore Further
- Structure, function, and history — Zwick’s analytical triad
- Ontological categories — Function alongside structure
- Functional breakdown — When function fails
Related Concepts
- Structure — what enables function
- System — where function happens
- Adaptation — changing function over time