Information Systems, the components of Cyberspace, are the most complex engineering products yet produced. Their components range from physical devices, like transistors, which require careful design and manufacture through operating systems and applications packages, to the intricacies of the internet and world-wide web. To tame that complexity modularisation is required: a system is designed in modules each responsible for only part of the overall functionality and therefore able to be produced largely independently of the rest of the system. The coarsest division in the hierarchy of modules follows the very terms 'hardware' and 'software'. At the programming level, a module is a procedure invoked by a higher structure.
Many (some would argue all) modules could, in principle, be performed instead by a human with consequent change only in efficiency, not functionality (for example spelling checking, piloting an aircraft or otherwise behaving like an expert, performing arithmetic and balancing a spreadsheet). Indeed historically, advances in Information Technology might be viewed as the automation of routine human behaviour (or even, in some cases like chess, not considered routine). A typical example of such modular replacement occurs in Searle's Chinese Room [14] in which human comprehension -- the standard factor at stake there -- is argued not to follow from manual execution of an otherwise-automated module.
To reflect the way in which information systems are constructed, understood and executed, Information Ethics must support modular and incremental reasoning. If one module is performed differently, the analysis of the whole system should be modified by replacing only the argument concerning that single module, not begun again from scratch. For example, if manual operation of a module moves it outside Cyberspace, the corresponding piece of argument should be removed and the remainder reworked without it. Information Ethics must be modular.