In Section 1.4.3, we have briefly introduced evidence-based reasoning in various domains (see Figure 1.10, p. 28). In this section, we start with discussing the complexity of evidence-based reasoning by using the “connecting the dots” metaphor. Then we discuss in more detail evidence-based reasoning in a representative EBR domain, intelligence analysis. We conclude this section with other examples of evidence-based reasoning. Then the following chapters will address the development of such systems and of knowledge-based agents in general.
HOW EASY IS IT TO CONNECT THE DOTS?
The “connecting the dots” metaphor seems appropriate for characterizing evidence-based reasoning. This metaphor may have gained its current popularity following the terrorist attacks in New York City and Washington, D.C., on September 11, 2001. It was frequently said that the intelligence services did not connect the dots appropriately in order to have possibly prevented the catastrophes that occurred. Since then, we have seen and heard this metaphor applied in the news media to inferences in a very wide array of contexts, in addition to the intelligence, including legal, military, and business contexts. For example, we have seen it applied to allegedly faulty medical diagnoses; to allegedly faulty conclusions in historical studies; to allegedly faulty or unpopular governmental decisions; and in discussions involving the conclusions reached by competing politicians. What is also true is that the commentators on television and radio, or the sources of written accounts of inferential failures, never tell us what they mean by the phrase “connecting the dots.” A natural explanation is that they have never even considered what this phrase means and what it might involve.
But we have made a detailed study of what “connecting the dots” entails. We have found this metaphor very useful, and quite intuitive, in illustrating the extraordinary complexity of the evidential and inferential reasoning required in the contexts we have mentioned. Listening or seeing some media accounts of this process may lead one to believe that it resembles the simple tasks we performed as children when, if we connected some collection of numbered dots correctly, a figure of Santa Claus, or some other familiar figure, would emerge. Our belief is that critics employing this metaphor in criticizing intelligence analysts and others have very little awareness of how astonishingly difficult the process of connecting unnumbered dots can be in so many contexts (Schum, 1987).