DISCUSSION: THE LIMITS AND POTENTIAL
OF MEASURING DEVELOPMENT
IN THIS BOOK I HAVE PRESENTED THE EVIDENCE AND methods behind an analytical tool, the social development index. It therefore seems sensible to close not with a set of conclusions but with a more open-ended discussion of what this tool can, and cannot, do.
I start with two sections discussing possible problems with the index. First, I offer a few comments on margins of error and falsification. One of the greatest drawbacks of the neo-evolutionist indices was that because they were not really built to answer specific questions, it was very difficult for their designers to say exactly how they could be falsified. Error terms depend on the questions being asked, and in the case of the why-the-West-rules question, we can be reasonably precise about how much error can be tolerated before we have to conclude that the index is misleading.
In the next section I turn to the issue of displaying the data. There is no such thing as a neutral way to display statistical information; each format tends to emphasize one or more dimensions of the index over others. I have systematically opted for what seemed to me to be the simplest formats, favoring linear-linear graphs whenever possible, but other formats also have merits.
I then return to the issues considered in chapter 1, asking how the index described here might contribute to a unified evolutionary theory of history. I am optimistic that such a theory is possible, and that a social development index can be an important part of it. Finally, I