Editing Modularity (section)

==Consistent themes==
Comparing the use of modularity across disciplines reveals several themes:

One theme that shows up in psychology and biology study is innately specified. ''Innately specified'' (as used here) implies that the purpose or structure of the module is predetermined by some biological mandate.

''Domain specificity'', that modules respond only to inputs of a specific class (or perform functions only of a specific class) is a theme that clearly spans psychology and biology, and it can be argued that it also spans technological and organizational systems. Domain specificity would be seen in the latter disciplines as specialization of function.

''Hierarchically nested'' is a theme that recurs in most disciplines. Though originally disavowed by [[Jerry Fodor]], other psychologists have embraced it, and it is readily apparent in the use of modularity in biology (e.g., each module of an organism can be decomposed into finer modules), social processes and artifacts (e.g., we can think of a skyscraper in terms of blocks of floors, a single floor, elements of a floor, etc.), mathematics (e.g., the modulus 6 may be further divided into the moduli 1, 2 and 3), and technological and organizational systems (e.g., an organization may be composed of divisions, which are composed of teams, which are composed of individuals).<ref>Schilling, M.A. 2002. Modularity in multiple disciplines. In Garud, R., Langlois, R., & Kumaraswamy, A. (eds) Managing in the Modular Age: Architectures, Networks and Organizations. Oxford, England: Blackwell Publishers, pp. 203–214</ref>

''Greater internal than external integration'' is a theme that showed up in every discipline but mathematics. Often referred to as autonomy, this theme acknowledged that there may be interaction or integration between modules, but the greater interaction and integration occurs within the module. This theme is very closely related to ''information encapsulation'', which shows up explicitly in both the psychology and technology research.

''Near decomposability'' (as termed by Simon, 1962) shows up in all of the disciplines, but is manifest in a matter of degrees. For instance, in psychology and biology it may refer merely to the ability to delineate one module from another (recognizing the boundaries of the module). In several of the social artifacts, mathematics, and technological or organizational systems, however, it refers to the ability to actually separate components from one another. In several of the disciplines this decomposability also enables the complexity of a system (or process) to be reduced. This is aptly captured in a quote from [[David Marr (neuroscientist)|David Marr]]<ref>Marr, D. 1982. ''Vision''. W.H. Freeman, p. 325.</ref> about psychological processes where he notes that, "any large computation should be split up into a collection of small, nearly independent, specialized subprocesses." Reducing complexity is also the express purpose of [[casting out nines]] in mathematics.

''Substitutability'' and ''recombinability'' are closely related constructs. The former refers to the ability to substitute one component for another as in John Blair's "systemic equivalence" while the latter may refer both to the indeterminate form of the system and the indeterminate use of the component. In US college curricula, for example, each course is designed with a credit system that ensures a uniform number of contact hours, and approximately uniform educational content, yielding substitutability. By virtue of their substitutability, each student may create their own curricula (recombinability of the curriculum as a system) and each course may be said to be recombinable with a variety of students' curricula (recombinability of the component within multiple systems). Both substitutability and recombinability are immediately recognizable in Blair's social processes and artifacts, and are also well captured in Garud and Kumaraswamy's<ref>Garud, R. and Kumaraswamy, A. 1995. "Technological and organizational designs to achieve economies of substitution". ''Strategic Management Journal'', 16:93–110.</ref> discussion of economies of substitution in technological systems.<ref name=":0" />

Blair's systemic equivalence also demonstrates the relationship between substitutability and the ''module as a homologue''. Blair's systemic equivalence refers to the ability for multiple modules to perform approximately the same function within a system, while in biology a module as a homologue refers to different modules sharing approximately the same form or function in different organisms. The extreme of the module as homologue is found in mathematics, where (in the simplest case) the modules refer to the reuse of a particular number and thus each module is exactly alike.<ref name=":0" />

In all but mathematics, there has been an emphasis that modules may be different in kind. In Fodor's discussion of modular cognitive system, each module performs a unique task. In biology, even modules that are considered homologous may be somewhat different in form and function (e.g., a whale's fin versus a human's hand). In Blair's book, he points out that while jazz music may be composed of structural units that conform to the same underlying rules, those components vary significantly. Similarly in studies of technology and organization, modular systems may be composed of modules that are very similar (as in shelving units that may be piled one atop the other) or very different (as in a stereo system where each component performs unique functions) or any combination in between.<ref name=":0" />

{| class="wikitable"
|+Table 1: The use of modularity by discipline<ref name=":0">Adapted with permission from Schilling, M.A. 2002. "Modularity in multiple disciplines". In Garud, R., Langlois, R., & Kumaraswamy, A. (eds) ''Managing in the Modular Age: Architectures, Networks and Organizations''. Oxford, England: Blackwell Publishers, pp. 203–214</ref>
|-
! Concept
! Technology and organizations
! Psychology
! Biology
! American studies
! Mathematics
|-
| Domain specific
| X
| X
| X
|
|
|-
| Innately specified
|
| X
| X
|
|
|-
| Hierarchically nested
| X
| X
| X
| X
| X
|-
| More internal integration than external integration (localized processes and autonomy)
| X
| X
| X
| X
|
|-
| Informationally encapsulated
| X
| X
|
|
|
|-
| Near decomposability
| X
| X
| X
| X
| X
|-
| Recombinability
| X
|
| X
| X
| X
|-
| Expandability
| X
|
| X
| X
| X
|-
| Module as homologue
| X
|
| X
| X
| X
|-
|}