“The One, the Few or the Many?”: Using Independence As a Strategy in Engineering Development and Modeling

Abstract

There are choices about the number of ways to approach and understand a problem. Sometimes finding the one right analytical approach is sufficient. Other times, such as with the Manhattan Project, the use of many approaches is desirable. Increasing independence among multiple analytical approaches, i.e. using a pluralistic approach, can be a good strategy to get knowledge to make decisions and understand a system. We considered two frameworks that have attempted to provide advice to engineering and scientific practitioners on when and how to use multiple analytical approaches. The RAND Corporation’s parallel path strategy, as described by R.R. Nelson, is a way of using independent engineering efforts to explore what parts of the design space are feasible, as well as what the cost and schedule would be for different designs. Richard Levins and William Wimsatt’s focus on model independence provides motivation and insights for using multiple models to assess the same system. While these approaches may appear different, both rely on using a group of analytical approaches where the individual members are independent – or different from—one another. Comparing these two approaches provides suggestions about how to utilize independence to address uncertainties in design and model-systems. We argue that the deliberate creation of independence among engineering developments and models should be tied to key uncertainties in the model or system. With relatively low uncertainty, choosing one approach may be acceptable. Both suggest that there can be (but are not always) benefits from using multiple approaches, which can increase accuracy and reduce cost. Using a few independent approaches – as opposed to many – may be more desirable when there are only a few bounded uncertainties about the system.