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CS News Fall 2011

CS News:
Professor John Knight - A Convincing Argument for Safety


Professor John Knight

Over the last several decades, we have ceded day-to-day control of a variety of essential systems to computers — and by and large, they do a superb job. They fly our aircraft, monitor our nuclear power plants and control our electric grid.

The problem is that these computer systems are so complex that it is difficult to determine if they are sufficiently reliable. To make matters worse, they are typically developed by thousands of people and modified over time. “In the past, the safety community believed that you could avoid catastrophic failure by applying a series of best practices to computer system development,” says Professor John Knight, a specialist in safety-critical systems. “But these best practices don’t always reflect the circumstances that will determine the safety of a system.”

Knight is conducting research on an alternative approach used in Europe. There, system developers create a safety argument that sets out their safety claim for a system and that documents their rationale for belief in that claim.

Knight’s work in the field has taken him in a number of directions. He has been investigating how to redesign the engineering process so that the safety argument actually drives development decision processes. He has also explored mechanisms for assessing confidence in arguments about safety-critical systems.

In addition, he has collaborated with members of U.Va.’s Department of Philosophy on building better arguments. “After all, if you are going to construct a logical argument,” he says, “you might as well consult the experts.”