WJ Clancey — Visualizing Practical Knowledge
Introduction
When people talk about “knowledge” they usually refer to descriptions—facts, theories,
heuristics that are often written down—and “knowledge in the head”—tacit
understanding, which is conceptual. We must be careful not to equate descriptions with
concepts or to identify all knowledge with scientific or professional expertise (Schon,
1987, Clancey, 1997a). I will call the aspect of knowing that is not technical, “practical
knowledge,” and show how it can be studied and exploited in the design of information
technology.
To improve how we envision knowledge, we must improve our ability to see knowledge
in everyday life. That is, visualization is concerned not only with displaying facts and
theories, but also with finding ways to express and relate tacit understanding. Such
knowledge, although often referred to as “common,” is not necessarily shared and may be
distributed socially in choreographies for working together—in the manner that a chef
and a maitre d’hotel, who obviously possess very different skills, coordinate their work
(Scribner, 1984; Greenbaum and Kyng, 1991; Resnick, et al., 1991). Furthermore, non-
verbal concepts cannot in principle be inventoried (Clancey, 1997b). Reifying practical
knowledge is not a process of converting the implicit into the explicit, but pointing to
what we know, showing its manifestations in our everyday life. To this end, I will
illustrate the study and reification of practical knowledge by examining the activities of a
scientific expedition in the Canadian Arctic last summer—a group of scientists preparing
for a mission to Mars.
Practical knowledge challenges for a Mars mission
As might be expected, going to Mars involves technical problems in rocket propulsion
and navigation. But a Mars mission also requires that we invent a new kind of operations,
a new way of relating ground and space activities, with corresponding support tools that
will make a three-year mission possible. We must reconsider how work is done because a
Mars mission cannot be carried out like an Earth orbital mission: 3 years cannot be
planned by the minute; traditional operations roles are inverted (ground becomes
transient, space becomes permanent); and the average 40 minute communication delay
prevents ongoing “looking over your shoulder” and assistance from technicians and
scientists in the “backroom.” In short, we must understand how practical knowledge is