Mapping politics

So what is it about a map that makes data more political than a table or a graph? When sensitive data is taken from tabular formats and placed on a map that represents the places that we inhabit, what happens to our view of the data? I am working on a project right now that is using a GIS program to represent data thematically on a map of the Catholic Dioceses of Ireland. Here is a jpg of the base map that I am using; this map arose from a project that I worked on with Omar Sarhan and the Department of Geography, NUI Maynooth in 2008. You can see from this base map that the Catholic Dioceses are somewhat different in composition to the counties of the island (red lines), there being only 26 of the former with significant ‘island’ parishes in the middle of adjoining Dioceses. As great a job as he did, Omar had difficulty trying to source Catholic parish boundary data that was uniformly available and accessible for each of the Dioceses. At the end of the project, only two Dioceses had parish-level detail, but that’s another story.

So, for example, if I was to place this data in a table that lists the Dioceses in column one and the data in column two, how is that different from a representation of the same data placed on each of the 26 spaces that are the Catholic Dioceses? Do those seeing these data relate to their area’s data  more directly? Do words matter less than lines on the map? Working with the particular data for this project right now, I am having to explain why its representation in this format is potentially a lot more politically sensitive that in ‘traditional’ tabular formats.