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An Introduction to Incommensurability, or, hang on a minute, that doesn't add up

In the previous session we looked at the possibility of 'mix and match' methodologies either through selecting a methodology according to the problem situation (contingency approach) or by combining different methodologies (blended approach). While it can be argued that, in practice, this is what tends to happen anyway, are these solutions as straightforward as they seem?


Incommensurability occurs when two things lack any criteria for comparison. The four philosophical positions outlined in this module represent four paradigms for thinking about systems development, which some argue are incommensurable. If this is the case, then there are no common criteria for comparison between the four positions and hence no systematic or objective that can be used to decide which to adopt. This last session in the module will examine the views for and against the incommensurability of paradigms.

For incommensurability

The arguments for incommensurability are mostly based on the need for there to be some level of philosophical consistency in meaningful action. Here the argument is that one can not act on (or possibly even conceive of) something that one does not believe in. Without a certain level of level of philosophical consistency, system design activities would, at best, degenerate into a matter of individual taste and/or prejudice, and at worst, into chaos.

Against incommensurability

The arguments against incommensurability are mostly based on pragmatic considerations. While philosophical purists might argue that it is possible to find 'paradigmatic transcendence' (i.e. discover a meta-paradigm that transcends the differences between paradigms) most practitioners argue that shifts between paradigms, over time and within a project, provide sufficient consistency for incommensurability not to be an issue in practice.




On-line Articles

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Lecture notes

The notes for this session are available as a presentation (in pdf format) - lecture notes for session 9

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