Scenarios resemble time lines (event chronologies), but they differ from time lines in two important ways: (i) scenarios are hypotheses about the causal connections between events, about the influence of prior events on subsequent events, and (ii) scenarios contained "conjectured" events, or events for which there is no direct evidential support (other than prior events in a scenario).

How does one go about developing a scenario? A good way to start is by working with a time line and then using your imagination. Recall the time line that Slick developed. The figures below (together with a figure, Figure 1, that slightly modifies the "grammar" set forth in my notes about time lines) --, the figures found below illustrate some scenarios that can be hung on such a time line "scaffold."

This is the slightly-modified system of notation:

In this collection of figures

• darkened circles represent evidentially-supported (evidentially-suggested) events, and
• empty circles denote entirely hypothetical events.

Figure 2 shows one possible scenario:

Figure 3 depicts another possible scenario:

In this scenario the investigator conjectures that Peter Plaintiff is not an innocent victim of a shooting but had a sudden, preexisting need for money, perhaps because of a loss of employment or for some other reason, and that Peter went to the Happy Valley store on the night of April 1 with the idea of taking money from the store.

Other scenarios are clearly possible; other scenarios can clearly be constructed. For some example see Fabrication Paper.

Of what use are scenarios?

They serve at least several important purposes.

One purpose is related to the basic empistemological point, or premise, that factual issues in litigation involve, implicitly or explicitly, hypotheses about connections between space-time events. (Perhaps this is the reason why juries tend to construct "stories" when they deliberate about evidence and factual issues -- even if the lawyers in the case have not done so.)

Scenarios may also serve as the basis for the formation of rhetorically-appealing renditions (by trial lawyers) of factual hypotheses. (There is ample anecdotal evidence that the telling of "stories" is important for effective trial advocacy. Scenarios are probably an implicit requirement for the formation and communication of rhetorically-effective stories.)

The final purpose is of most interest to us at the moment: scenarios are important indicators of the possible (and, sometimes, probable) existence of relevant evidence. See note on retroduction. See also, more generally, the discussion of retroductive reasoning in Fabrication Paper.