Is GIS a tool or a science? There's a lengthy and dense paper on the matter here. Could someone offer a more digestible summary?
I would say that a GIS is a tool, while geographic information science is a science.
Great question Charles.
They are both. GIScience has a much bigger scope and depth. GIScience investigates better methods, methodologies to achieve something. For instance, developing an new algorithm to process remote sensing imagery and extract certain features.
GIS is a tool, used by others to achieve desired results. A GIS user uses certain algorithms to fulfill a purpose - extract all roads from a remote sensing image.
EDIT: as jwise noted GIS = Geographic Information Systems GISciente = Geographic Information Science
One interesting distinction that Michael Goodchild has noted is between GIS and statistics: many modern statistical methods were developed in the nineteenth century, but were difficult and costly to compute by hand. Only with the advent of the personal computer did the costs fall sufficiently to enable widespread use of computationally expensive statistical methods.
Early geographic information systems (GIS), however, were partially driven by the availability of technology and later searched for relevant problems and scientific methods. This process has come full circle, with the formation of the field of geographic information science (GISci), which provides the intellectual framework for handling issues raised when using a GIS.
A Geographic Information SYSTEM is, well, a system. It comprises tools, data (what good is the tool with nothing to work on?), the people who use it and make it work, and all the glue between those parts (workflow, geoprocessing models, etc.).
There is a tendency to think all one needs to do is go out and acquire arcgis/manifold/ermapper/qgis/whatever, a "GIS", and then start whipping out maps. In truth that's only the barest beginning.