Connexions module: m13765 1
Case Analysis Module: Therac-25
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William Frey
This work is produced by The Connexions Project and licensed under the
Creative Commons Attribution License
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Abstract
This module, designed for the EAC Toolkit (NSF SES 0551779) will test the Toolkit and Connexion's
ability to network dierent online and oine sources for ethics across the curriculum. It consists of
four components designed to provide students with tools for carrying out an in-depth analysis of the
cases found at www.computingcases.org; it also makes substantial references to the draft manuscript of
a textbook in computer ethics entitled Good Computing: A Virtue Approach to Computer Ethics. (The
book will consist of the cases displayed at Computing CasesTherac-25, Hughes Aircraft, and Machado
plus seven additional cases all developed through NSF projects DUE-9972280 and DUE 9980768.) The
module presents the case abstract and timeline. It then refers students to Computing Cases where
they will nd the case narrative, history, and supporting documents that provide background necessary
for analysis. The case abstract and timeline introduce students to the basic outlines of the case. The
accompanying decision point taken from the case provides students with the necessary focus to carry out
an in-depth analysis. Students respond to the decision point by working through four stages: problem
specication, solution generation, solution testing, and solution implementation.
Computer Ethics
Case Module Template
By William J. Frey
Module Introduction:
The Therac-25 case is what Hu and Frey call a thick, historical, evaluative, big news and bad news case.
Tackling cases of this complexity requires both careful thought and considerable skill. Especially important
is the ability to sift through the case details, documents, and conicting narratives. The purpose of this
module is to provide students with a structure to tackle big, long, and complicated cases. Students will receive
frameworks to help them structure the case's ethical and social problems. They will also be provided with
decision points that will help them to enter into the case and take up the standpoint of a participant. The
module presented below can be linked to materials that can be found at www.computingcases.org. Nancy
Leveson, in Safeware:System Safety and Computer (515-553), also provides an excellent and comprehensive
account. Excellent advice on how to teach the case, updated information, and clear explanations of the
programming errors are provided by Chuck Hu and Richard Brown in "Integrating Ethics into a Computing
Curriculum: A Case Study of the Therac-25." The materials posted at Computing Cases were all developed
through NSF projects DUE-9972280 and DUE 9980768.)
The module presents the case abstract and timeline. It then refers students to computingcases.org where
they will nd the case narrative, history, and supporting documents that provide background information
necessary for analysis. The case abstract and timeline introduce students to the basic outlines of the case.
The accompanying decision point taken from the case provides students with the necessary focus to carry out
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Version 1.8: Oct 10, 2011 7:08 am GMT-5
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http://creativecommons.org/licenses/by/3.0/
http://cnx.org/content/m13765/1.8/
