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Therac-25 Case

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Socio-Technical Analysis

Ethical Analysis


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Using the ImpactCS Grid to Understand Therac-25

The ImpactCS approach to ethical analysis was devised by a panel of ethicists, computer scientists, and social scientists. The point is that any particular computing system can be analyzed from both the perspectives of social analysis and of particular ethical issues. The grid you see below was designed by the panel to serve as an analytic tool in thinking about any system. The idea is that each of the ethical issues can be analyzed at each of the levels of social analysis.

For instance, in this case, safety is the primary concern. But we need to think about issues of safety at individual, group, national and global (or international) levels. Each of these levels brings forth different issues and different ethical concerns. In addition, the grid reminds us that safety issues are only one of many issues that might concern us in a case.

We unpack these concerns in a series of documents that you can access by clicking on the highlighted cells in the Framework below. For Therac-25, we provide an extensive analysis of safety issues at all four levels. But a complete analysis would ask about privacy issues (important for reporting systems), property rights (is the software for Therac-25 a product or a service?) and all the other issues. We provide rudimentary suggestions about these issuses in the links.


Ethical Issues

Quality of Life

Use of Power


Property Rights


Equ.ity and Access

Honesty and Deception

Levels of Social Analysis


Quality Power Safety Property Privacy Equity Honesty


Quality Power Safety Property Privacy Equity Honesty


Quality Power Safety Property Privacy Equity Honesty


Quality Power Safety Property Privacy Equity Honesty