The dissemination of divination in roman republican times

While many good and detailed models have been developed to analyze cultural
transmission (Boyd & Richerson 1985; Cavalli-Sforza & Feldman 1981), the limitation of
sources available in historical research imposes some limits on what we can use. I will only
use one particular method from epidemiology, which is usually just the starting point in an
epidemiological study. It is called a Web of Causation. It is essentially a simplified model of
the stipulated causal relationship between different factors promoting a disease in a
population. Usually this serves as a point of departure for further empirical analysis. But
before we can start to apply this method we have to be more specific as to what it is we are
studying.
In epidemiology the object of study is the distribution of disease in a population. Even here
it is not an exact science to diagnose what counts as a case. Often it is based on clinical
opinion (Silman & Macfarlane 2002: 3). Precise diagnostic criteria need not therefore be
specified. In the cultural version the object of study is some sort of cultural entity. This entity
need not be the property of one individual, but can depend on several individuals. In our case
it is divination.
Divination depends crucially on a person being motivated to pose a question he cannot find
answers to in other ways. In the unlikely situation that human misfortune was eradicated, it
would undermine the basis of divination. Likewise, if someone could learn anything with
certainty through ordinary human perception, divination would also loose its basis. What
determines the choice of one divination practice compared to another depends on how
credible it is generally taken to be. I have tried to capture this credibility with the term
credibility value. It is likely that the credibility value is important for a divination practice.
We therefore have to evaluate the factors that increase and decrease the credibility value of a
divination practice. Another factor of importance is the utility of the practice; after all, if the
divination practice only allows you to receive perfect advice as to whether you should buy a
blue or a red car, it may not be of much use anyhow. A third and more loose factor is the
knowledge of the divination practice and a general understanding of how it works. This is
captured in the cognitive model used to conceptualize the practice. It is therefore possible to
sketch the stipulated web of causation for divination impetrative and oblative divination
respectively.
We stipulated that the following factors were important for the success of impetrative
divination (see fig.6.1.)
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